Contents:
RCA/GE TV (CTC175-187+) Solder Connection and EEPROM Problems
Copyright (c) 1994, 1995, 1996, 1997, 1998
All Rights Reserved
Reproduction of this document in whole or in part is permitted if both of the following conditions are satisfied:
Problems with bad solder connections, mostly in and around the tuner are very
common with several series of late model (e.g., CTC175-187 and higher chassis)
RCA/GE/Proscan TVs. Ignoring these erratic and intermittent problems can lead
to serious damage including failure of the EEPROM and possibly other expensive
ICs. Therefore, it is essential to deal with the solder connections as soon
as these symptoms appear. The repairs are straightforward though perhaps
tedious. Thompson may reimburse for reasonable cost of repairs.
Also, some LXI TVs may actually be of RCA/GE manufacture: LXI is sold by
Sears. If the model number starts with 274.something it is an RCA CTC176/7
or 187 chassis. (pwhite4@aol.com (PWhite4)).
Sometimes, similar symptoms are the result of bad solder connections elsewhere
on these chassis. Check around the pins of large components like power
transistors, power resistors, transformers, etc. However, since problems with
the tuner soldering are so common, this is usually the place to start.
Note that many other RCA chassis as well as other manufacturer's TVs are also
susceptible to similar symptoms with similar causes.
Some of the common symptoms include:
* Random power cycling. It may come on in the middle of the night!
* Picture shifts or changes size vertically or horizontally.
* Picture turns to snow or shows other reception problems.
* Picture turns to random display of time or other data.
* Noisy or muted sound, volume buttons have no effect.
* Remote has no or unexpected effect.
The articles in this document have been compiled over the last few
months from postings on the USENET newsgroup sci.electronics.repair.
Contributions are welcome to increase the coverage of this set of notes
as well as those for the very similar set of problems and solutions for
late model Sony TVs: "Sony TV Tuner and IF Solder Connection Problems".
(Symptoms are very similar and repair requires removing and resoldering
connections inside the tuner and IF boxes. Unfortunately, at least on
some models, removing these modules is a real treat!)
Proper attributions will be made for all providers of solutions. I apologize
if I have incorrectly referenced you or left your name off. I will be happy
to make any necessary corrections in the next revision. Please email me
with any additional sections. I would very much like to improve the details
of the repair procedure if possible.
Corrections and additions to any specific symptom or solution are also
welcome.
I have no connection with Thompson Electronics or any other manufacturer
of consumer electronics. These articles have been included unedited except
for some spelling, grammar, and format cleanup.
Here are some typical sets of symptoms resulting from bad solder connections in and around the tuner of these late model TVs: "I have a 26" RCA television with a "squeezed" vertical and "snowy" picture, at its worst times it also shuts off and on again. This problem is occurring 50% of the time, I noticed that tapping the panel where the 75ohm and rca connectors are attached will realign it temporarily. Is this a symptom of the "solder cracking I read about in RCA's or a bad EEPROM and if it is a bad EEPROM why does a smack offer a quick fix and why is it shutting off and on?" "This picture is short vertical about 1/2 inch at top and two inches at the bottom. Anyone seen this problem on this chassis. Is it possibly related to all the bad solder joints in the tuner area?" "I have an RCA TV with the following symptoms: * The audio will suddenly switch to maximum volume. * The volume buttons on the TV and the remote control have no effect on the volume during this time. * If the blaring condition occurs and I attempt to adjust the volume very low, then when the condition returns to normal, the volume comes back at this very low volume. So the signal to adjust the volume must be received by the controller while the speaker is blaring. * If I use the remote to mute the volume a slight diminishing in the volume can be noticed, but the mute is not accomplished. * If I cycle power, the problem persists, unless I leave the unit off for a while (sometimes 30 seconds, sometimes a few minutes) before turning it back on. * If I adjust the volume to minimum and turn on the muting, just using my stereo for sound from the VCR, the TV will still begin to blare in short burst and then eventually come on and remain at full volume." "My parents' RCA TV has lost some volume, and is now barely audible when on full volume. The controls are all electronic and on screen. Is this a known problem with RCAs, and could there perhaps be a pot I could adjust inside to 'boost' the volume?" "I have a GE 31" (about 3 years old) where the picture moves down the tube, like a DC offset is present. The top of the picture is down about 1/3 from the top of the screen and the bottom of the picture compresses. Occasionally, the picture turns to snow. If I turn off the power and back on, it temporarily cures the problem. Could these symptoms also be caused by poor tuner connections?" "I have the SAME TV, and mine is about 1/5 off. Some channels also have lots of Snow etc." "I tried using a VCR as a tuner & running the signal in through the RCA plugs in the back. Same difference. I still experience the same problems. Does this rule out the turner?" "I am having the following problem with the TV: * The screen will go black and display: 1:5P A-- (the "P" is sometimes an "8" or possibly a "B") * the screen will suddenly go from showing a picture to show nothing but "snow". There is no sound, the remote control won't shut it off, the power button on the set won't shut it off, it has to be shut down by unplugging it. * When it is plugged back in it will sometimes come back on without pushing the power button or using the remote, screen shows nothing but snow, no sound. * Sometimes when it is plugged back in it works normally (won't come on until you push the power button or use the remote), it then acts normally except there is no sound until you use the remote or the buttons on the set to adjust the sound." "My RCA XL-100 TV has begun to develop a life of its own -- it intermittently goes crazy." "My two and a half year old GE 25" set started having troubles with the picture shrinking from top to bottom, losing signal strength (snow) and now shifting of the picture off the bottom of the screen. This would occur usually right after turning it on, and sometimes could be cured by turning off the set and turning it back on again. Lately it has been getting worse so I took it in for repair. Lo and behold, there were several GE and RCA sets there that had similar complaints. All ended up needing an "S-kit" from GE, an item apparently supplied to the repair center for free from GE. I needed a crystal as well. This sounds like some kind of widespread problem that maybe should be looked at as if it is an unwritten warranty? Anyone care to comment?" "I have a 27" GE Model 27GT610. About a year ago a problem started to develop. It would take turning it on 2-3 times before the picture came up. Initially all I would get was a black screen and static on the speakers as if it wasn't on a broadcast channel. Over the last year it has progressed to taking me 20-30 minutes to get the picture to come on. I suspect it might be a corroding startup relay but am unsure. Does anyone have a part# and component# that could point me in the right direction? Any other suggestions would also be appreciated. Thanks, btw I already have the FAQ. "I have a 2 year old RCA XL100 television. It has worked just fine up until the last 2 or 3 weeks. I now have severe problems with it and am hoping that someone who reads this posting will recognize the symptoms and help steer me in the right direction to fix the damned thing! I know of another person who had the exact same model and 2 years after he bought it, it started acting up in the same way, so I assume this is a well documented problem that I'm seeing... When the set is turned on, the "reception" on some cable channels is terrible, but others are fine. Turning off and on again fixes those channels, but within a few seconds, the reception goes bad again. There is a time display function and a mute function on the TV. When I press a button, the channel displays in the upper right corner. Likewise in the lower left corner with mute. When the TV is misbehaving, these words "walk" down on the set. The MUTE word goes so far that it's unreadable since only the tops of the letters show. Turning off and then back on temporarily solves the problem. Whenever this phenomenon occurs, the top of the picture gets "squashed" down and a black band appears at the top of the screen. When I look at CNN, the sportsticker at the bottom is almost unreadable and it appears that the lower part of the picture is forced into the non-viewable area of the screen. If I struggle through these problems for an hour or so, then everything is almost back to normal, but the problems do appear intermittently. When I switch over to the VCR tuner, my reception problems are solved, but I still get the screen "walking" behavior, so it looks to be more that the tuner chip (unless that also controls these extra functions). Does anybody know about this problem??? Is it just a bad chip or component that I can replace? What should I do about it? (I'm a EE and am quite capable of fixing simple soldering problems and such myself). Before I take it to a repair shop or buy a new one, I'd like to see if I can fix this one... in a word... HELP!" "I have an RCA FMR70ER TV that only works when the room temperature is warm. If the temperature is cool the TV will never turn on . "The problem tends to show up after the TV has been on for a few minutes. The picture will appear to have signal problems (i.e. a snowy picture), and then the top line of the picture will begin to dip down, until it is approximately 25% of the way down the tube. There is just black above it. When its really bad, the picture will be just snow, the top will drop down almost half, and there will be a very bright band at the bottom of the screen. Now, one way to remedy this problem is to shut the TV off, and then back on again. Sometimes this will 'reboot' the TV and the picture is fine. Sometimes it doesn't work. The problem is beginning to become more persistent and annoying!" "I have a General Electric 21" (or 23"...can't remember) colour remote control television. It's about two and a half years old. The problem we're having is that the picture is 'dropping' off the bottom of the screen. This sometimes happens shortly after turning the TV on, or sometimes not for some time after turning the TV on. What happens is that the whole picture seems to move down a bit on the screen, then it moves a little further, then before you know it, there's about a couple of inches of black at the top of the screen, above the picture. You can't see the bottom of the picture because it is now below the bottom of the screen (i.e. the picture doesn't just shrink). Sometimes a bright white line will appear at the very bottom of the screen, and after a snapping sound the picture will jump back up (sometimes back to the top, sometimes just part of the way up). Then it happens all over again, kind of random. If you turn the TV off, wait a few seconds, then turn it back on, most of the time (not always) the picture will start out back at the top of the screen as it should." "2 year old ge has tuner problem. Some channels part snowy others very snowy. Sometimes don't work at all. But, only on some channels.( Vertical is not shrinking). Any case histories?" "I have a CTC177 that instead of the two relay clicks of the degaussing circuit will click 6-8 times when it is first turned on. Signal was coming from U3101 - changed IC, no change in problem. Works fine once it's warmed up, anyone else have this problem?" "I have a weird problem, or at least I have never seen it before. I have a GE colour television that when it is initially turned on the lower channels are not existent (snowy) and the upper channels are crystal clear. When the TV has been on for about half an hour, all the channels are crystal clear." "I had/have the same problem w/ an RCA CTC175. Picture shrunk down to letterbox size. When i was going to check the joints, I turned it on (hasn't been used in a couple weeks), to see if the picture came in full size, but to my surprise i had no picture. When i say no picture i> mean it's like my cable has been disconnected. After a little fiddling here and there i came up with the following. * Cable box hooked - no picture on any channel. * Straight cable to TV - only cable channels 54, 55, 64, & 76 (nice and clear). Should i go ahead and resolder the tuner connections and see what happens or does it sound like the microprocessor may be out?" "I have a GE TV 25GT543, CTC187AA chassis with a vertical intermittent where a whack on the side fixes it. Is this 'the resolder under and around the tuner' fix? Is there anyway to tell exactly which connection is really the bad one rather than randomly resoldering everything within sight? I like the feeling I get when I know that I have really found the source of the problem rather hope I got it....." "Volume and channel OSD shifted off to the right so that channels are not visible. Closed captioning and customer menus shifted to the left. Tuner shield was done about a year ago and is ok. Problem occurred after a power surge that caused C7 the main filter capacitor to fail. Otherwise the set seems to work fine. Horizontal and vertical sync pulses are present on pins 26 and 27 of the micro."
Caution: See the document: "Troubleshooting and Repair of Consumer Electronics Equipment" before attempting to repair or replace the tuner module. You *must* have proper soldering equipment and desoldering tools. Attempting to remove, solder, or replace the modules(s) without these *will* result in a mess and a very expensive bill when you finally take your TV to a professional. Someone brought me a TV to look at. After a little prodding, it was learned that he had lent it to a friend and it died after six months or so. The 'friend' then attempted to replace the tuner module based on the description on a refused estimate from a TV service shop. He did not have proper soldering equipment - perhaps only a Weller 100 W soldering gun. Needless to say, the TV did not work - nearly every pad on the PC board under the tuner had been destroyed. I had to run wires from the pins on the tuner to the their destinations on the mainboard. It was not fun. Luckly, no permanent damage was done but it could have easily been a lot worse.
There seems to be some disagreement on whether to use the 'special RCA soler' or not: (From: Charles Godard (cgodard@iamerica.net)). The solder RCA recommends doesn't flow properly. The only returns I've had after doing this repair have been because of using their solder. The best way to do the job is to use regular 60-40 lead tin and apply the right amount of heat with a controlled heat solder gun. Too much heat and you peal the board, not enough and it won't stick or will crack again. I first flux the joint's with rosin solder paste. I clean my tip before starting, and a couple of times during the job. Again, I use a controlled heat solder gun. This seems like a simple job because it is 'simply' soldering. Don't be fooled. I've been at this business for twenty years and am an expert at soldering. Of the first dozen or so of these sets that I worked on, I had a couple of solder spills that cost me a couple of extra hours to locate because I didn't realize I had made a spill and assumed another problem. Another hazard is that if you are not skilled and attentive, you may loose one of the small resistors or capacitors from the board. If you find it, then you've got to figure out where to put it back. :> If you flex this board you may cause a crack on a resistor or capacitor lead that could be very difficult to find. In addition to all that, there are some hidden joint's that won't be apparent to even a skilled technician the first time he does the job. (The stuff in the middle :) If you are a trained technician and do soldering regularly and have a controlled heat gun, and are used to working with these flimsy consumer type circuit boards, then you can probably do it with no problem. There are some jobs that are suited for do-it-yourselfers and I don't hesitate to tell a guy if I think he can do it and save a few bucks. This is not a job I would recommend for the average guy to tackle. I can think of very few solder job's I've ever done that require more skill and attention than this one. Sorry, I'm sure that's not what you wanted to hear. However, next time you have a problem, just ask. I may have an easy fix for you, and will be glad to give it if I do.
Here are some of the responses - many from experienced techs who fix (too) many of these sets: (From: J. Caldwell). Following the instructions packed with the service bulletin will allow a proper job to be performed. Overheating the board substrate and surrounding components will cause future and horrible failures. The connection will NOT look shiny but shouldn't look bubbly or crinked, the solder will only flow if you use the special solder paste, rosin core solder will cause it to corrode oddly so clean all rosin core off the board. A standard Weller station does the job quite well and experience has shown me that the full repair with jumpers and the special solder (as the bulletin states) is the best thing to do for reliability and customer satisfaction. I was mistaken in earlier ramblings. (From: (JohnSon) johntrum@netonecom.net)). This sounds like the typical shield/pcb solder joint problems that RCA has had made famous with their CTC175/177 chassis. It's a common problem. We have fixed literally "tons" of them. I'm guessing it would be this series of chassis because you also mentioned the EEPROM. The symptoms you mentioned are all associated with these bad solder connections and there are even more symptoms that can appear from this same problem. No video, color drop, etc. are other common symptoms. Just get your solder iron hot and do a good job soldering ALL bad connections related to the shield areas and you'll be in business again. You'll still just have a "new model" RCA, but, the symptoms you describe should go away. If you catch it while it is in the "smack" condition, you shouldn't need any parts. If you wait until it dies completely, you could be looking at an IC or EEPROM replacement. You DON'T want to replace the EEPROM, trust me! (From: Jaclyn (lambert@sos.net)). Possibly.. :) Once you think you've got all the solder connections done - you've only just begun. Also check for cracks on the pads surrounding the tuner grounds. Oh, you might want to order an extra pound of solder before you begin.... (From: Louis A. Iannotta (bouncer@nauticom.net)) The problem is bad solder connections under the tuner shield. The bad connections cause false signals to the EEPROM which cause the reduced vertical height. RCA just recently has issued a bulletin and a kit to repair the connections with a special "elastic" solder which isn't supposed to crack under temperature fluctuations. (From: Chuck (Nordic@osuunx.ucc.okstate.edu)). I would open the tuner control module and solder all the posts that are around the periphery of the board. Also on rare occasions, the solder connections break on the main board jack that the plug from the tuner control module attaches to. Resolder them also. Good luck. (From: JohnSon (johntrum@netonecom.net)). I am sure you are probably talking about the "infamous" Thompson (the RCA/GE owners) bad solder joint chassis'. They started with the CTC175/176/177 and from what I see they have continued on up through the CTC187 at least and maybe further. You can confirm your chassis number by checking inside the back of the set or on the back of the set sometimes. These sets have a variety of symptoms accompanying the bad solder joints. The two you listed are only a couple. When repairing these sets, all of the trouble areas should be repaired at that time. You will be just asking for more problems if you don't. If you are very technically minded, you may be able to repair this yourself. If not, you could try a local repair shop. I have heard repair prices for this range from $50.00 to $140.00. I don't have any idea what the shops are doing to repair them for $50.00, but, I suspect they may be just going in and soldering the obvious bad joint, at the time. As I mentioned, this would only be a temporary repair at best. The majority of the problems are under the shield of the "built into the board tuner", but, there are others also. I know our charge to repair them, complete, runs about $100.00. (lots of soldering to do the job right.) If you decide you need further info, post what model and chassis number you are working on. If it is the problem that I think it is, I can tell you, from our complete repairs, we have never had a recall on these chassis for this same trouble and we have literally repaired tons of these things. (From: Kevin (giddy@ac.dal.ca)). In RCA/GE chassis CTC-175,176,177, There is a common problem with bad solder on the tuner shields and around the microprocessor shield. The symptom is usually intermittant snowy picture and reduced vertical height. Please do not be misled into trying to troubleshoot the vertical section as you may be wasting your time. Often you can confirm if this is your problem by grabbing the RF input connector firmly and wiggling it while observing the picture. Thomson seemed to have solved the problem around the end of 1993. I have done lots of these. (From: BELJAN E (lvpy67c@ix.netcom.com)). It is the CTC series chassis and the tuner solder joints break. You should take the set in as soon as the problem develops to avoid permanantly damaging the set. The S-kit is most likely the repair kit for the GE series (S stands for solder) it has special flexible solder that will keep the tuner from going again. (From: Marlin (mister-m@ix.netcom.com)). Yea! These RCA/GE all are having the problem of loose grounds. They are mostly around the Micro and Tuner grounds. If your having problems with the picture becoming snowy you may have to remove the tuner shield and do those also. The intermitten power on and off may also be around T4401 Flyback Transformer. Check or resolder this area also. (From: Mark Paladino (paladino@frontiernet.net)). I'm not familiar with this model in particular but the symptoms you describe my be similar to another well documented RCA tuner problem. That problem involves tv's of about the same vintage and after a year or so develop symptoms similar to what you describe. The solution to those maladies is resoldering all of the tuner shield connections where the shield connects to the pc board. I have accomplished the "fix" on several RCA TVs of that vintage with similar tuner symptoms and in each instance was able to completely correct the problems and restore the tv to workable condition. (From: Mr. Caldwell (jcaldwel@iquest.net)). It is not a picture tube. Why is it that some people think that the picture tube is bad when the set has a snowy picture? It's solder connection in the tuner, the tuner is not replaceable it is part of the mother board. Call RCA and ask them if they will foot the bill. If not call an authorized repair center and get an estimate. (From: Lawrence E. Manion (MANION.L.E@worldnet.att.net)). Get the problem fixed now or the connections will cause enough noise on the microprocessor that it will eventually 'deprogram' the EEPROM and you'll need that replaced and it's quite expensive as this part holds *all* adjustments. There are only 2 or 3 controls that are manually aligned. I have fixed many, many TV's with this problem. It is common to all RCA, GE, LXI model. The problem is easy to fix, but its hard to get the area ready for repair. To those that are brave remove the back, pull out the chassis, (some plugs must be removed so mark as needed) turn the mother board over. Now find the metal can near the cable connection. Their will be 4 solder connections, remove (its harder than it look) then remove shield to expose inner tuner area. You will need to solder all ground inside and around the shield mound you removed, and the connection that was unsoldered from the shield. Now solder any connections that looks bad including surface mounded components i.e.: transistors, IC, and the cable input connections. reassemble in reverse order then your problem will be gone. Be careful not to bridge any connections that is NOT connected a good mag light is a must! I normally charge $70 labor for this job takes about an hour of work and 8 hours of playing time to confirm the problem is fixed. Only one out of 20-30 TV's required parts. (From: John F. Reeves (jreeves@uwf.edu)). On the CTC175 family of chassis, the tuner shield soldering job must be performed before any other troubleshooting can be done as this procedure will correct many such symptoms. the tuner shield on the bottom of the board must be removed and resoldering around the shield structure should be done. There are four posts that need to be resoldered, and check for any other suspicious looking connections. There are other circuits to check also. Give the entire board a good look. When that is done, see if there is any change in your symptom. These chassis also have a service menu that can accessed by pressing and holding the menu button then momentarily pressing the power and volume up buttons. CAUTION!!! If you are not familiar with these procedure DO NOT MESS WITH IT!!! You can really foul up your set. This procedure is included in the service manual. (From: Paul White (pwhite4@aol.com)). I advise resoldering the chassis, all ground and shield lugs that feed through the board, especially around and under the tuner shield. If you can't do this take it to a shop and tell them the symptom and that it needs resoldering, if they don't know what you are talking about take it somewhere else. If you wait to long the problem will get worse and will damage IC u3201, the EEPROM IC, which means a complete alignment of this IC. Most techs will fudge these settings and may be ok but don't wait till that occurs for your own benefit. (From: Bill A. (Lucy27@ix.netcom.com)). Yup!! Actually, the whole tuner shield/microprocessor shield grounds all are poorly soldered. You can sometimes with the naked eye or magnifier see some of the loose connections, but if you solder just a few now you will be back in there in a month or less guaranteed. So just do the whole solder job. It is actually a much better repair and you can rest easier at night knowing that you resolved the problem rather than patching it. The 'classic' problem is prone to the CTC175 through CTC187 chassis. I'm also seeing the same problem on the newer generation CTC178 through CTC189 chassis. Instead of RCA redesigning their 'On-Board' tuners, they would rather re-design the solder thats been around for hundred years give or take. Good Luck!!!
(From: Mr. Paul (jcaldwel@iquest.net)).
RCA now offers a 'kit' to repair these, the only thing in the kit that is of
any use is the paper template that shows exactly where to solder. But I'll
give it a shot:
First under a bright light, after removing the bottom shield look for solder
splashs or components that may have been desoldered by heat.
Kind of short....view from bottom with RF connector toward top:
__|RF|____________________________
| |
| |
| |
| |
| |
| X |
| |<
| X |< Bad connections in lower right
|_________________________________|< corner causes vertical bounce.
Two X's will cause a snowy pix, they are posts from the shield that are
supposed to poke through the bottom but don't quite make it. A small round pad
that may look like a test pad or that has a component lead poking through the
board are good points to solder.
Also when you remove the board in some sets the leads on a filter to the left
of the deflection/color/etc. IC can be bent and short, usually resulting in
a snowy pix or just snow. (View from bottom, IC is below tuner, filter is to
left, has three in-line pins.
(From: Ken Bouchard (bouchard@ime.net)).
On all of these RCA chassis, with the 'sandwich' type tuners, the shield must
be removed, and then carefully solder everything you can see on the top and
bottom of the tuner. Then re-install shields and solder them in as many places
as you can as well.
A special solder (very very expensive) is sold to the repair centers, that has
an elasticity to it to allow a correct fix for this problem. However, you can
get away with just normal soldering in most cases, to cure the problems.
I cured our set of all of this, by soldering and soldering.... Most of it has
to do with grounds that pass through the tuner, as well as 0 ohm jumpers and
such that have bad soldering....
The connections that are bad, are feed-through holes as well as all
connections around the perimeter of the tuner can. Each feed-through can be
spotted and rca supplies you with a mask. There are about 15-20 connections
in all. RCA has a fix for this, which uses a very special ($700 a pound)
solder which has elasticity to it. That and the solder mask helps to make a
fast repair. Also look about for ends of any chip components that were poorly
soldered. Got to have a fine point tip, or your likely to short something out
in your effort to repair.
Be advised that there are many surface mount transistors, chip caps, and
resistors that are in the tuner, so you will need a fine point low wattage
or temperature controlled soldering iron for these.
(From: Tech 7 (gscivi@aol.com)).
You don't really need a template! Just solder the shield all the way around,
and at each point where it comes through the chassis. (this is easily observed
by removing the top shield cover as well). and instead of adding jumpers, I
simply solder each corner of the bottom shield to the pc board. Jumpers work
just as well, so if you want to follow the instructions of the people who
didn't make it right in the first place, be my guest. A close inspection will
also reveal the locations to solder. And resolder the upc shield too!
"I need some help with this GE tv. Its a 1993 vintage model 27GT613 with a chassis number of CTC177BH." I resoldered the tuner shield and connections. However, when I powered it to check to see if I had resolved the intermittent tuner situation I found that I receive stations 2-13 with much snow in the picture." (From: Nice address (jbc@blkbox.com)). If you are sure that you did not make a mistake in soldering, check the RF coils. The coils are small wires through the PC board in the tuner section. I have seen a few cases where the wire was probably not clean when soldered. You may have to scrape each wire and solder it again. A bad MIXER coil may cause snow on some channels and be ok on others. EEPROM alignment will not solve the problem.
Almost any problem can be due to a bad EEPROM since it contains the 'boot' information needed to set up all the TV's subsystems. These include reception, raster, picture, menu, closed captioning, color, sound, and other symptoms The most common cause are the bad tuner solder connections discussed elsewhere in this document. However, EEPROMs can and do fail on their own. Where the TV has died totally - particularly after having had prior problems caused by bad solder connections - the EEPROM may be corrupted so totally that the set cannot even 'boot': If you have an oscilloscope, monitor the DATA line from the EEPROM when you turn the set on. Normally data should appear for a short time and then disappear. If there is a continuous stream of data on the DATA line, the EEPROM is probably corrupted. (For the CTC177, it is U3201, pin 6 if you don't have a schematic.) Replacement EEPROMs are now available from: * Dalbani (1-800-325-2264) for over 150 different RCA/GE chassis between CTC175 and CTC187. About $3 in singles. * TV Man (tvman@mindspring.com)). I now have all Thompson, RCA, and GE EEPROMs in stock. Web: http://www.mindspring.com/~tvman/. "I have a GE model 25GT505 that suddenly developed a problem. Here's what happened: For 2 years the set has worked fine. Went on vacation for two weeks - house at 63 degrees. Used TV for 3 hours one night with no problems. Next morning, picture is bad as follows: Picture is as wide as the screen but the vertical height is compressed. Picture starts about 1/3 of the way down the tube and extends to about 1/3 of the way up from the bottom. Furthermore, the bottom traces seem to be overlayed resulting in brighter than normal lines." (From: DCAVS (dcavs@aol.com)). This is a common problem for all GE, RCA, ProScan televisions of a variety of chassis. It is due to a design and manufacturing flaw. You should call RCA Customer Relations at 317-587-4151 and take it to a Thompson Authorized Service Center. (Thompson Electronics of France owns the names, RCA, GE, and ProScan for Televisions. ) Thompson has been sending their customers $75.00 for carry in service and $95.00 for in-home service. This amount should cover the bill as any technician who knows what they are doing should be able to complete the repairs quickly. There is a small chance that the data in the EEPROM IC that stores all the setup data has become corrupted. In this case the set needs to be reprogrammed to operate correctly. This is a time consuming process and can have a great affect on the quality of reception.
"I have a dead RCA CTC175 chassis in my shop that I have traced down to a bad EEPROM. The tuner shield solder connections were repaired, but how do I read the EEPROM contents when the set can't be fired up? We have done a number of these EEPROM change outs, but never with a dead set." The following applies specifically to the GE model 31GT657 but the general approach (with appropriate changes in chip IDs and pins) applies to many other models: (From: seabulls@unlimited.net). If you do have troubleshooting experience, scope pins 5 and 6 of U3201 when the set is first plugged in to see if data is being exchanged momentarily. if the data continues on and on, then the eeprom is bad. If data occurs for just a moment then settles into a steady 4.8V, then troubleshoot the horizontal drive circuitry, and if there is no data and no 5V on pin 8, then troubleshoot U4101 and the 1.5meg resistor off pin 4 (I think) for open. As Hank pointed out, you could have a blown fuse and shorted flyback although they are unlikely on this chassis. If you do have a blown fuse, U4101 is most likely shorted and the 140V rectifier is probably shorted too (CR4106 I think is the location). The flyback, while possible, is the last thing I would try. (From: Videotek (dmcdonal@Direct.CA)). You are right, it is probably the EEPROM. When you install the new one, the set should fire up, but the horizontal sync will likely be out. Just enter the service menu, and reprogram the eeprom. There are about 80 parameters that need to be set. To verify that it IS the EEPROM, scope the data line on the EEPROM, and plug the set in. If you see a burst of data, and then nothing then the EEPROM is OK. If you see continual data, then the EEPROM is bad, as the CPU is trying to find it, and the eeprom is not responding. If no burst of data, then check your power supply. Everything from soup to nuts can be blamed on that blasted EEPROM. No audio, no vertical, no color. All bad eeprom. I have changed hundreds, and have 3 sets in my shop now waiting for their turn to my bench.
(From: Mr. Caldwell (jcaldwel@iquest.net)). There are three sections to the EEPROM: * The factory identification section is where the generic microprocessor gets the data on what chassis it is in. If this get's scrambled the set might think it's a PTV or other size set or has a different type of audio system, etc. This is only alterable by a device that can directly write to the eeprom and cannot be modified by the TV (except when something goes wrong) or the technician without knowing the data and having and I2C eeprom programmer. * The factory adjustment section is that part that stores technician alterable settings such as horizontal hold, stereo alignments, etc. and can be adjusted by entering a code and then using the remote or chipper checker from Thompson. * The Customer adjustment section holds all customer controls and is adjustable in normal use of the set. Since this chip is an I2C bus memory chip it should be quit easy to buy one of each chip from RCA and pull out the chassis coding for each chip then buy the IC in bulk at 1.00 a pop. It's an interesting chip anyway and worth experimenting on. I think Phillips has such a programmer available since I2C is there baby. BTW, you should get the FULL 'service' model number and FULL chassis number when ordering parts. Having the service model number makes it easy to look up the full chassis number, you only need the full chassis number to actually get the eeprom but some parts require the 'service' model number. The service model number is the model number in smaller print on the back that has 3 or more extra digits on the end.
(From: Matthew L. Kruckeberg (MKRUCKEBERG@pol.org)). Various configurations require various EEPROMs. Stereo/Mono, AV jacks/no AV jacks, PIP/no PIP, linear power supply/switch mode power supply, pincushion circuitry/no pincushion circuitry, hotel set/consumer set, and the screen size are all variables stored in the section of the EEPROM not accessible from the on screen menu. There also at least 2 different microprocessors. The early sets were produced without closed captioning and require a different micro. I agree that there is a lot of confusion caused by the variety of EEPROMS and the lack of properly trained techs to service these sets. I have seen quite a few butcher jobs to the tuner shields, wrong EEPROMs installed, and incorrect or no realignment of the EEPROM values. Unfortunately there are many people who think they are qualified to service these units just because they claim to know how to solder. When in doubt about the correct EEPROM check with the local RCA parts distributor with a chassis number or better yet buy a manual.
(From: Raymond Carlsen (rrcc@u.washington.edu)). There are dozens of different models, each with different functions supported by "instructions" in that EEPROM. You could buy one of each (chip) and clone them with a burner, but unless you have hundreds of sets to repair, it wouldn't make sense to go to all that trouble. There are now quite a few after-market sources for those EEPROMS. The specific one for the chassis you're working on must be installed or the set will not work properly. Some of the 'programming' of the chip must done *after* it is installed, by the tech, such as the tuner setup adjustments. Each tuner is of course different and so requires tuning. Other factory-programmed EEPROM data cannot be changed by the tech during setup... that's the basic reason the EEPROM must be replaced when the tuner grounds corrupt the data. Rather than start from scratch each time the chip must be changed, the tuner settings can be 'copied' from the old chip (Note: not always possible), i.e. readings written down on paper and then entered into the new chip during the setup adjustments. After you've done the tuner resoldering, install a socket for the EEPROM. Unplug the TV, install the replacement chip and power up the set. With the set still plugged in (but turned off, of course), remove the chip and install the "bad" one and copy the "parameters". Put the replacement back in and enter the values you copied down. The set should now work properly. I've been able to do that on all but one set I've worked on. You will not find that information in the RCA service literature. It's essentially a workaround, dreamed up by a tech to save time. Bless that one! Lastly, don't get me started on why Thomson treats it's servicers like [censored]. Chipper Check... Nipper Net... all paid for by techs who can barely afford the coffee they're drinking. Who needs it? You *must* buy RCA's test fixtures and software to service and do even simple adjustments on the new sets! I pass. If that's leading edge.....
"I have a GE 27 inch stereo TV (model 27GT613, chassis CTC177BH) on which I just repaired the tuner shield cracked solder connections." (From: Michael D. Long (longm@tusmp004.allied.com)). A friend of mine who repairs machines said it was the EEPROM before he even scrolled done to see that you had had a repair tech look at it. He also has told me that to replace the eeprom you need to get the correct eeprom from RCA and prior to removal all of the factory settings need to be recorded from service menu(he doesn't remember exactly how to get to it without a tv in front of him--check a sam's photofact for details--you can also get the correct part number from that too. (From: "Nice address" (jbc@blkbox.com)). Do not trust Sam's photofact for the correct part number. There are about 14 different part numbers for CTC177. They may all use the 24C02 but the default values are different. Hey, NAP uses a 24C01 and they charge about $25 for it. Has anyone built the I2C programmer yet? (From: YonyMar (yonymar@aol.com)). Your problem could be caused by a bad EEPROM. First you need to get the correct replacement EEPROM. The letters at the chassis will get you the correct part number, i.e. CTC177XX. Before you remove the old EEPROM enter the software service mode and copy down all the settings so you can write them into the new EEPROM. I would suggest using a socket also.
The July 1997 issue of "Electronic Servicing & Technology" magazine has an article "Servicing EEPROM problems in RCA televisions", by Bob Rose. (Editor: Nils Conrad Persson (CPersedit@aol.com), Sales: Electronic Servicing & Technology, 76 N. Broadway, Hicksville, NY 11801, 1-516-681-2922. Editorial office: PO BOX 12487, Overland Park, KS 66212 1-913-492-4857. ES&T has also had articles on CTC17x servicing and of course all sorts of other repair of consumer electronics in general. While not something you will find on the newsstand, you might be able to get a peak at one if you snuggle up to your local electronics repair shop :-). (From: Ted Gondert (vcrepair@bbs.industrynet.net)). The article is good with some useful information. There is a chart with average values to use for setup/alignment of the new EEPROM. Compared the printed numbers to what I wrote down from RCA CTC175A that was repaired by replacing the EEPROM using a socket and switching the old for new EEPROM after turning on the set to read the old parameters. Then setting the new ic to match. His numbers are close, so maybe TV would work about the same, just set new EEPROM to the average values in the chart. The article also explained cure for the no sound problem caused by the speakers being muted by pin 29 on microprocessor high. That can be fixed by removing resistor R1915 in the muting transistor circuit, etc., as mentioned on the sci.electronics.repair newsgroup many times. But, he said RCA doesn't approve of it and recommends this technique: 1. Disconnect AC from chassis by unplugging the set. 2. Unsolder pin 8 of EEPROM (and isolate from pad). 3. Use a pick to short pin 8 to the pad, temporarily restoring B+. 4. Plug in set and turn it on. 5. Remove the pick and therefore the short circuit (to the pad). 6. Use the menu function to select speaker on-off. 7. Turn speaker back on. 8. Unplug set and resolder pin 8. I haven't tried it but sounds interesting. Wonder if some other EEPROM problems can be cured that way? ;-).
Restore defaults I assume. From: jcaldwel@iquest.net (Mr. Caldwell) Trick # 722 * Press and hold menu then press power and then press volume + * Release menu * Press menu (vertical will collapse don't panic) * Press menu * Press power You may have restored the eeprom, it's worked for me with some very weird problems with the eeprom where I'd normally have replaced the eeprom. Note: You need the FULL chassis number and failing that the FULL model number to get the correct eeprom. The full chassis number may be on the back if the set but it is always inside and, it begins with CTC get all the digits after it. I.e CTC177AE CTC177BA CTC177BA2 etc etc The generic number on the eeprom will only get you an un-factory programmed eeprom that will not work or work *very* strange. The full model is the 'Service Model' in small print near the large print model number. There are several digits after it that point to the correct chassis number and thus the correct eeprom number.
Where the set does not come on at all or shuts down immediately, the following MAY get you going. WARNING: If the shutdown is actually being caused by excessive HV, this could result in a dangerous and/or destructive situation! (From: Wes Black (wesmike@aol.com)). On the "T" Chip solder a temporary jumper from terminal 26 to ground this will bypass the HV shutdown circuitry. You should be able to fire the set up and enter into the program mode. When finished be sure to remove the jumper. This procedure has worked many times for me. Oh Ya!! don't forget to resolder the tuner section first. (From: J. Caldwell (jcaldwel@iquest.net)). Setting the horizontal frequency to low (by accident or from corrupted EEPROM) may cause the TV to shutdown or give the with the appearance of being dead. To fix this is you need to check the value of the main 'critical safety capacitor' a.k.a 'redundant capacitor' a.k.a 'tuning capacitor' This is a larger blue capacitor that is connected from the collector of the horizontal output, it can be connected to ground in smaller sets or is run through the pincushion circuit to ground. Once you have the RCA part number order one, solder this in parallel to the existing capacitor and the set will fire up and not activate the high voltage shutdown circuit. You can enter the factory setup, reset the horizontal frequency for a stable picture, turn the set off and remove this added capacitor. I've used this sporadically only to be able to copy down all the other values in an EEPROM since if this happens on it's own it's a good idea to replace the EEPROM. This is not needed if you have the RCA signal generator for these newer chassis. (From: Tech 7 (gscivi@aol.com)). Don't let the set run too long with the shunt capacitor either! This does work however, and is even the suggested method by RCA itself! After a number of these badly machined chassis, I have learned to count the service menu items in the event this very symptom crosses my bench. (once the resoldering has been accomplished, there is no need to replace the eeprom!) ; Clip shunt cap to horizontal output, turn set on (full AC), enter service mode, press Volume Up 76 times, Channel Up once, you are now in the horiz oscillator adjustment parameter. Volume up/down will adjust the oscillator to near sync. As soon as you see two or three slanted sync bars shut the set down, remove the shunt capacitor and try the set again. Isn't this fun?!
In many cases, while the contents of the EEPROM have been corrupted by write errors caused by bad solder connections, the actual chip is undamaged and really does not need to be replaced. The following isn't something you could likely justify for one repair but if you have a motel full of RCAs, it could easily pay for itself and then some in saved time and money! Note: I have not tested this software/device so I do not have any first hand knowledge of its performance. The hardware interface schematic is free from the Web site or you can buy it preassembled. (From: Jim Lawnichak (tvdr@mail.emeraldnet.net)). If you get the chance, stop by http://www.emeraldnet.net/~tvdr and take a look at Quick Clip. The program eliminates most tuner alignments and repairs the EEPROM while its still in the set.
(From: Paul R Gendreau Jr. (tvman@biddeford.com)). The 175/6/7 (and more) chassis has a SPEAKER MUTE feature for those chassis that sport speaker output jacks, and the speaker mute is also used during the POWER ON or POWER OFF functions. Even if your model doesn't have the jacks - the software and hardware to mute the speakers exists! When the EEPROM data is being corrupted by the poor solder connections - one piece of data that can become corrupted is the bit that is set to turn the SPEAKER MUTE circuit on. Since the on screen display for that model has no menu feature to allow the customer (or technician) to turn the speakers back on - you cannot correct the data in the EEPROM without an EEPROM programmer. There are some servicers that are using EEPROM programmers to access the data. A easy and cost effective work around is to disable the speaker mute circuit in hardware. This involves the removal of a diode or a surface mounted device (SMD) transistor - what part to remove depends of the chassis involved. If Q903 is present on the foil side of the board - remove it. If Q903 is not there, then CR1953, a diode, will be present on the component side of the board and it should be removed. Only one component, not both, will be in a given TV. Removal of whichever of these 2 is present will disable the speaker mute circuit. If the rest of the EEPROM data is OK or can be corrected by the on screen menu then this procedure will save the replacement cost of the EEPROM (less than $5.00 wholesale) and the tedious job of performing about 100 alignments to the tuning system which is *REQUIRED* after EEPROM replacement. On the negative side: The customer will find a difference in the way the TV operates! The software in the TV mutes the speakers during POWER ON or POWER OFF functions. This make both of those functions very quite. With the speaker mute circuit disabled there will be a small burst of noise during both of those functions. The level of the noise is not objectionable - but it will be a cause of concern for customers that are not forwarned. I would guess that over 80% of our customers choose the modification and subsequent cost savings rather than have the EEPROM replaced. (From: Woodie Morris (bwmorris@bellatlantic.net)). Here's what I do: * If it's a stereo model, short Q903 emitter to base. (surface mounted) * If mono, cut or remove CR1953.
(From: Darren (fatal@net.bluemoon.net)). For the RCA series CTC chassis that have been produced in say the past 6 or 7 years, there is a 4 pin IC near the front of the chassis..... that is the EEPROM. Every chassis has letters such as CTC175 A or K or E2 etc. When you call for this part you need to know the exact letters of the chassis, because the programming in the eeprom differs for every chassis. I have a complete list ng of all eeproms to chassis part numbers. The info on the ic is useless. The majority of the EEPROMs run about $4 to 6 which is not all that much. We stock all RCA EEPROMs. How do you know when your RCA needs a new EEPROM? The two most common reasons are: no power (TV will not turn on) or no audio. Yes, sometimes the TA audio chip goes bad, or the fat flameproof resistor that feeds the main voltage to that IC burns up, or solder loosens from the board. When you determine you need a new EEPROM, and you put it in, audio should come back. But if it does not and you know the audio IC is good, chances are you may have zapped the IC or the new one is defective. These EEPROMs are extremely sensitive. To determine if it is the EEPROM, you need to desolder a pin on the main IC and apply a 4.6 volt source to it to see if it will bring audio back. I don't have the schematic handy so I cannot tell you which pin that it is but that is a definite way to determine a bad ic due to an EEPROM. Once you replace the EEPROM, you need to reprogram the set. off of the main menu you have to put the TV into service mode. If you were smart (and the TV was not in shutdown) you copied all the codes from the old EEPROM, so you know the settings for the new one. Knowing these codes is extremely important! There are something like 50 main options 100 more just for the tuner set-up. Get the service manual!
"Yes, please send me a more complete diagram and the EEPROM work-arounds as I see that the no-audio problem has come up a couple of times on the sci.electronics.repair newsgroup. BTW, how exactly does a bad EEPROM result in no audio?" (From tvman@biddeford.com). The 175/6/7 (and more) chassis has a SPEAKER MUTE feature for those chassis that sport speaker output jacks, and the speaker mute is also used during the POWER ON or POWER OFF functions. Even if your model doesn't have the jacks - the software and hardware to mute the speakers exists! When the EEPROM data is being corrupted by the poor solder connections - one piece of data that can become corrupted is the bit that is set to turn the SPEAKER MUTE circuit on. Since the on screen display for that model has no menu feature to allow the customer (or technician) to turn the speakers back on - you cannot correct the data in the EEPROM without a an EEPROM programmer. There are some servicers that are using EEPROM programmers to access the data. A easy and cost effective work around is to disable the speaker mute circuit in hardware. This involves the removal of a diode or a surface mounted device (SMD) transistor - what part to remove depends of the chassis involved. If Q903 is present on the foil side of the board - remove it. If Q903 is not there, then CR1953, a diode, will be present on the component side of the board and it should be removed. Only one component, not both, will be in a given TV. Removal of whichever of these 2 is present will disable the speaker mute circuit. If the rest of the EEPROM data is OK or can be corrected by the on screen menu then this procedure will save the replacement cost of the EEPROM (less than $5.00 wholesale) and the tedious job of performing about 100 alignments to the tuning system which is *REQUIRED* after EEPROM replacement. On the negative side: The customer will find a difference in the way the TV operates! The software in the TV mutes the speakers during POWER ON or POWER OFF functions. This make both of those functions very quite. With the speaker mute circuit disabled there will be a small burst of noise during both of those functions. The level of the noise is not objectionable - but it will be a cause of concern for customers that are not forwarned. I would guess that over 80% of our customers choose the modification and subsequent cost savings rather than have the EEPROM replaced.
The EEPROM data is different for the CTC175, CTC176, CTC177 and up chassis. For correct EEPROM alignments, access to the service data is required! You can install an EEPROM IC and only adjust the fist dozen settings, which deal with picture color and size, and this might result in a pretty good picture. But the TV will be far from correct in operation! Keep in mind that the tuner alignments are all set to mid-range when you install the new EEPROM. The tuner is therefore far out of alignment and requires full alignment! Proper alignment requires 3 things: 1. The correct service information for the chassis involved. 2. A signal generator capable of generating a signal on all cable channels. 3. A digital volt meter. While items 1 and 3 are either inexpensive or common, the signal generator is neither! For any problems you might have, I recommend that you find a FACTORY AUTHORIZED SERVICE CENTER for the brand you want repaired. There are several reasons for this suggestion. The primary reason is that only a FACTORY AUTHORIZED SERVICE CENTER has the service manual, technical support and access to original specification parts that should make the service of your product effective. In addition, only a FACTORY AUTHORIZED SERVICE CENTER will have knowledge of common problems which may occur in your model and may have suggestions from the manufacturer as to the best solution for those problems. Call the manufacturer to locate your nearest FACTORY AUTHORIZED SERVICE CENTER, or check your local Yellow Pages. Then call ahead to confirm that the service center is authorized not only for the brand of product you need serviced but for the specific type of product (for example, a Sharp FACTORY AUTHORIZED SERVICE CENTER may not repair Sharp CD players). If your product is less than 2 years old and you have concerns regarding early product failure, product quality, or repair problems, then you should direct those concerns to the manufacturer. Many manufacturers are eager to assist you if you take the time to call or write. If you do contact the manufacturer, it is important to have ready the model number, serial number and purchase date of your product. Many times they cannot assist you without that information. If you need to have a product repaired within the terms of the manufacturers warranty and you do not have your bill of sale (proof of purchase) then all is not lost! Most companies are prepared to send you a PROOF OF PURCHASE DOCUMENT if you call them with the model number, serial number and what you feel is the purchase date. This can take some time to obtain. If the FACTORY AUTHORIZED SERVICE CENTER you'll use has a fax number - ask the manufacturer to fax the letter to the service center. This will speed the repair along. (From: Matthew L. Kruckeberg(MKRUCKEBERG@pol.org)). Alignment is a must for proper operation. You will need a service manual for the instructions which should be available from your RCA distributor. You will also need a RF signal generator capable of generating the entire tuning range on the set (up through cable channels 120+). RCA sells one under the part number TAG-001 for about $200. There are about 150 parameter that will need to be aligned. With a lot of practice I have gotten the time down to about 45 minutes but the first ones became afternoon projects. Unless you plan on doing a lot of them you may be better off cutting your losses and referring the job to a shop with the needed equipment and experience.
"This RCA CTC175 came in with dead set diagnosis, as usual the problems was the EEPROM. I installed a new one and the set came on, but the new EEPROM came with the parameters set at default, and in some channels I had poor reception. When I get into the service mode I can adjust this parameters (100 and further) of the electronic tuner and I achieved a good reception changing this parameters. The problem is that, as far as I know, the way to save these parameters is pressing power, but when I restarted the set, got poor reception again. When I checked the parameters, the new data was there, at least in the display, but it has no effect in the reception. I think the procedure to save this parameters is not the correct." (From: Dogcatcher (Dogcatch@ix.netcom.com)). The correct procedure for aligning the tuner parameters is with a special piece of gear that you can purchase from RCA called a 'TAG001' generator. According to the manual once you adjust any of the tuning parameters you must align all. It is true, I've tried to "tweak" them in myself and you think it looks clear but when you turn the unit off or change the channel it is snowy again. I really suggest you check with RCA or a distributor and do it right. (From: PWhite4 (pwhite4@aol.com)). Pressing the power button is how you write your settings to memory. You are saving the parameters correctly. I have noticed on the CTC175 chassis that the settings for several of the parameters above 100 can affect the reception of the different bands in the tuner. 2 through 6 or 7 through 13 etc. can become snowy and clear as you adjust. If you don't have the RCA Tuner Alignment Generator (TAG) you just have to fudge until you get all the tuning bands acceptable. This is very time consuming and frustrating.
(From: Raymond Carlsen (rrcc@u.washington.edu)). Hopefully you saved the old chip. If so, you can use it to put the original values back for the tuner (assuming a snowy picture was not one of the original problems). There are no "ball park" values. Install a socket for the EEPROM. Fire up the set with the new chip, then power it down. Without unplugging it from the AC outlet, remove the new chip and put the old one back in. Turn on the set and run the menu and copy down *all* the parameters for the tuner. Turn the set off again and install the new chip. Put in the values you copied down and exit. Power down and unplug the set for a few minutes. Now, fire it up again and see if it works. You may have to reset some of the operational parameters like height and RGB values, but the tuner should be OK. I've used this technique several times with very good results. It saves having to start from scratch. The trick is that some of the values in the EEPROM are sent to the micro when the set is plugged in, and others when the set is turned on. That's the reason you don't unplug it to swap chips. It's a bit of a gamble with the new chip, but worth it for the time it saves. Good luck. (From: n3evg@aol.com) Next time you're faced with a RCA/GE dead set due to shot EEPROM from bad tuner grounds and connections...and worried that you can't dump the contents of the bad EEPROM to reset the tuning alignment and other parameters, do this: Remove the "bad" chip and solder an 8 pin dip socket in its place. Now take the new chip, plug it in the socket, plug in the set and turn it on. If all goes well and the set comes on (make sure you have already had all the solder connections repaired in the tuner before this of course) turn the set off and Without unplugging the set! Remove the new EEPROM and replace the original in its place. Turn the set on and enter the programming menu and proceed to copy down the contents of each of the memory registers. Do all of the tuning channels regardless of how many stations you are receiving. After you have completed, you can now replace the bad eeprom with the new one and program each of the registers. When finished, I then turn the TV off, unplug it wait a few seconds, plug it back in and make sure everything held. Sometimes I have to redo the horizontal hold and RGB registers. (From: jcaldwel@iquest.net (Mr. Caldwell)). * Pull plug! * Get an 8 pin socket and remove the new IC and reinstall the old IC in the socket (I'm hoping it's not zapped). * Plug set in and turn on. * Enter the access code to get the numbers out of the old EEPROM and copy them down (all entries - even channels you aren't using --- sam). * Pull Plug. * Put new IC in socket and copy in the numbers you wrote down. Now enter all the numbers from the old IC into the new IC and see if problem is solved. If not, I've forgotten which numbers are for the sound but since you copied the new IC's numbers you should have no problem when you read the service literature or someone here tells you what they are . Also pull the shield from the bottom of the tuner and resolder the grounds or expect to keep doing this. If you zapped the old IC then use the TV for target practice with a high powered rifle, I suggest .308 with a soft-point :-). Just kidding, you should probably get it professionally aligned. Unless you are willing to purchase the equipment needed to perform the tuner alignment and preserve your sanity or some kind repair shop owner who lurks here will accept the chassis you send them for repair.
"There are some secret codes on this GE TV. I had a Circuit City guy here before, and he held down the power-key or something & fiddled with the other keys during startup. Its almost like a computer's BIOS... Wild! Is this list available to mere mortals?"
(From: yonymar@aol.com).
The following is the setup procedure for the Thomson CTC 175/176/177 chassis.
Software setup procedure:
1. Press and hold Menu button, press Power, then Vol+.
2. Two displays appear at the right and left of center. Use the Vol+ button
to step the right display to # V76 (Group 1 setup V76).
3. Press Ch+ or CH- button to access parameter.
4. Press Vol+ or Vol- buttons to change software value.
Group 1, V76 Service Adjustment Parameters
Parameter Parameter Value Range
(Ch+/-) (Vol+/- to change)
00 Security pass # for Service Adjustment. Must set to 76. May not
advance until value set.
01 Horz freerun freq 00-31
02 Horz phase 00-15
03 Width (27/31 ) 00-15
04 Pin amp (27/31 ) 00-07
05 Vert center 00-15
06 Vert height 00-31
07 Red bias 00-127
08 Green bias 00-127
09 Blue bias 00-127
10 Red drive 00-63
11 Green drive 00-63
12 Blue drive 00-63
13 Security pass # for Chassis Adjustment. Must set to 77. May not
advance to higher param. until value set
Group 2, V77 Chassis Alignment Parameters
Parameter (Ch+/-), Value (Vol+/-).
14 to 24.
25 Security pass # for Tuner Adjustment (Must set to 78)
Group 3, V78 Electronic Tuner Alignment Parameters
Parameter (Ch+/-), Value (Vol+/-)
100 to 156.
Or more specifically:
(From: Glenn Watkins (blueribb@comcat.com)).
To access the second level of the service menu, first press and hold MENU.
Then tap the POWER and then the VOLUME UP buttons. You should see 4 zeros.
Press VOLUME UP until the right zeros read '76'. You are now in the first
level. Now press CHANNEL UP until you get to 13. Now press VOLUME UP again
to '77' on the right zeros.
You are now in the second level.
Thomson has a CTC 175/176/177 Technical Training Manual which has
all this information. Get a copy!
(From: P White4 (pwhite4@aol.com)).
If this set has the RCA CTC195/197 chassis you will need a lap top computer and
the RCA chipper check software to adjust the digital convergence beyond the 25
steps in the set up menu. RCA is forcing the software on us in this chassis
and any beyond it.
(From: J. Dow). The contents of address 0x00 of a CTC175/176/177 chassis V-line EEPROM is: bit 0 : 1=speakers enabled 0=disabled bit 1 : 1=tone high 0=normal bit 2 : 1=air 0=cable bit 3 : 1=autocolor enabled 0=disabled bit 4 : 1=closed captioning enabled 0=disabled bit 5 : unused bit 6 : unused bit 7 : unused The contents of address 0x00 of a CTC175/176/177 chassis W-line (with ST-9 micro) EEPROM is: bit 0 : 1=speakers enabled 0=disabled bit 1 : 1=tone high 0=normal bit 2 : 1=air 0=cable bit 3 : 1=autocolor enabled 0=disabled bit 4 : 1=closed captioning enabled 0=disabled bit 5 : 1=alarm enabled (4K EEPROM only) bit 6 : unused bit 7 : 1=adjust/setup menus disabled (commercial sets only) Now it's pretty clear, if the very first bit of your EEPROM gets cleared, the sound is gone. So, before you touch anything else, try writing 0x0F to address 0x00. If you're familiar with I2C, you know, address zero (and subsequent addresses if you're really unlucky) can be cleared easily by accident if one keeps the data (SDA) low and bangs the clock (SCL) long enough. On early sets, crazy things like that happen when the micro loses ground due to an intermittent tuner shield contact. Newer sets have the micro grounded thru other paths; nevertheless, EEPROM corruption is not completely eliminated. The EEPROM has a bunch of chassis dependent setup as well. Losing the channel list and labels is only an inconvenience, but losing the tuner setup can make the TV worthless if you can't realign the tuner. Losing some other values, such as hor. freq., B+ voltage, etc. can make the set blow the fuse.... The EEPROM map varies, even for the same chassis due to revisions. EEPROMs are *not* interchangeable! A factory new EEPROM does *not* have any correct alignment values: it's only good enough to start up! No TV made by Thomson(GE/RCA/ProScan) has ever had a non-volatile memory built into the microcontroller. Some sets have more than one EEPROM. Some ancient AccuScan boat anchors have the channel list in the *remote* and not the *TV* set. Once I had the pleasure of aligning a couple of hundred chassis in a couple of days; The defaults were grossly incorrect for tuner settings; failing minimum gain, tilt and out-of-band rejection specs. Some channels wouldn't come in at all, and a few sets wouldn't sync up. If you don't understand how the micro works and what's in the EEPROM, it's all black magic and you'll be cussing and replacing chips at random. If you know the game, you can fix a number of things without ever having to solder or buy a component!
(From: J. Dow). Tuning voltages for channels: 2,6,14,17,18,13,34,37,48,50,51,57,63,76,83,93, 110,117, and 125 are stored in the EEPROM. Primary, secondary and single tuned. Three values per channel. Every chassis is different because of individual variations in manufacture, coil knifing, etc. So the factory default middle values are no good for any particular set. You may try to copy the data from the old EEPROM from 0x54 through 0x8C into the new one. If that doesn't help, you really have to realign the set. If you have the factory ATE rig it's less than 4 minutes. If you have the service rig (TAG001 or similar), it can be half an hour or more. The procedure is described in the service manual. You need a VHF/UHF signal generator at least; a spectrum analyzer is also very handy but not essential. You also need a lot of patience if you're doing it by hand and not software.
(From: Zapper (zap@mhv.net)). I have run into at least 6 sets of the CTC177 family with bad channel up/down switches. One switch would get 'leaky'...stick on I guess. Everybody that I talk to has not seen this except fer me.
(From: mandacat@ix.netcom.com). I've had two RCA (Thompson) Chassis with intermittent vertical problems. The fix was to install jumpers to carry the ground through all points on the PCB. The interesting thing in troubleshooting this intermittent (prior to learning the cause) was that you would typically resolder what you thought was suspicious solder connections (grounds and components to the PCB). Now to the point. One of the sets I worked on lost sound AFTER the repair. I found out that if the set didn't have an 'Internal speaker off' option, one connection on the sound module was not soldered at the factory. I soldered it when I was re-soldering connections and I lost sound! If you have the schematic, I think its Pin 3 on the TDA7263 Sound Module which is not connected at the factory on sets that do not have the internal speaker off feature. Very Interesting! Another way to re-enable the sound would be to lift R1915 (you can cut it on the top of the chassis) from the collector of Q1903 (Transistor is always turned on for the case mentioned above).
"The raster is full height and is centered, but narrow at the top (less than half the width of the screen) and nearly full width at the bottom. The image is extremely distorted with gross convergence error at the sides. With the vertical drive connector removed from the yoke, the display consists of the red line sloped down from left to right, the green line roughly horizontal and the blue line sloped upward from left to right. The three lines cross approximately in the middle of the screen. The ends of the lines fit the shape that the raster has when the vertical yoke connector is in place. That is, the upper ends of the lines are closer together than the bottom ends. A rough diagram of this display may be viewed at All waveforms associated with the horizontal output, vertical output and high voltage transformer (T4401) appear as depicted on the service notes." My first thought was mechanical - the yoke is grossly tilted on the neck of the tube - the TV was dropped or something. This would result in both trapezoidal distortion and convergence problems (probably purity as well). Another possibility is that a portion of the horizontal yoke windings (the upper half, in this case) have opened due to bad connections or a break in the wire. This would mean that the R, G, B electron beams would see less deflection at the top than the bottom and could conceivably result in the severe convergence problems as well. A short between H and V windings of the yoke is not a likely cause as this would result in much more severe (if that is possible) problems (including much smoke). I do not know whether EEPROM problems could result in this but considering that so much is controlled digitally these days, I would not discount it as a possibility. Width and Height are digitally controlled so that some peculiar failure in an LSI chip or the EEPROM might be possible. First, eliminate the more likely possibilities unless you have an EEPROM to swap and quickly confirm. The November issue of Electronic Servicing reviews the 175 and the 177. It appears that the EEPROM in these sets can cause a great deal of weird problems. It goes into great detail and gives some circuit diagrams of these sets.
(From: Michael Caplan (cy173@freenet.carleton.ca)). The following has always worked for me: TCE Publications 10003 Bunsen Way Louisville, KY 40299 Phone: 502-491-8110
"I live in New Haven, CT and my local RCA/GE repair center tells me that a repair for this problem will cost about 145$??? Everyone who has responded to this post says under $100. Am I being taken to the cleaners?????????? That would really piss me off." (From: Paul R Gendreau Jr. (tvman@biddeford.com)). We are an RCA/GE factory authorized service center. (You should have this work done by an authorized service center because we are the ONLY people who understand where all the problems are with this TV!) Our rate for this job is $77.00. Furthermore, if the TV is less than 2 years old it would be a good idea for you to call RCA/GE (same company). Call consumer affairs at 1-317-587-4151. Explain how you feel about the cost of repair and the set not being very old. The numbers of posts in this group referring to this problem confirms that there is a PROBLEM. Ask them to reimburse you for part of the cost. RCA/GE/Thomson is a good company and has always been willing to address complaints from consumers.