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Hotronic PC-TBC and AR-31 Information Page

Before I get started with this particular page, I'd like to take a moment to tell anyone happening by this page who has plans to purchase any Hotronic product that they absolutely should not do so.

It's bad enough (though common and accepted) when a company making consumer grade products refuses to provide any support at all, much less actual technical material for products they've sold. It is completely inexcusable in the realm of professional grade products. I acquired a Hotronic AR-31 Time Base Corrector and soon found myself with questions concerning its operation. At least two separate e-mails from different accounts went completely unanswered by Hotronic.

It's even more insulting when the very first page on their web site clearly says "Please do not hesitate to contact us. We are glad to answer any of your questions." Yeah, right. I hate to slag on any company in public, yet it was apparently too hard for them to say that they couldn't help.

UPDATE! (March 2018) After this page spent a few years online, I was contacted by John Schmuhl with an offer to digitize his PC-TBC/AR-31 owner's manual. Mr. Schmuhl kindly digitized the manual for his PC-TBC, and sent it to me so I could make it available here. He also sent me a picture of a video transfer system used to transfer half-inch open-reel EIAJ videotapes to the S-VHS format. You can see that here, along with another picture of his AR-31 TBC unit. The manual weighs in at just over 3 megabytes in size and can be found right here.
I am still very much interested in hearing from anyone with more information about Hotronic or its products. If that's you, please feel free to send me an e-mail!

Meanwhile, I would sincerely like to thank Mr. Schmuhl yet again for going to the trouble of scanning his manual and sending the result my way.

In case you're not sure you should be here, this page isn't about foot warmers or similar products! I have no affiliation with the Hotronic company and nothing presented here is authorized or endorsed by them in any way.

General Information (what little I have)

Internally, the AR-31 TBC is nothing more than a PC-TBC card installed in a cabinet with its own power supply. Although the needed slot bracket is missing, there is nothing to stop you from installing the TBC board into a personal computer with ISA slots. (You would need to disconnect the wiring from the power supply in the AR-31 enclosure.)

Here are the product information (not much!) and specification pages for the PC-TBC product.
I also went ahead and grabbed the same for the AR-31: product information and specifications.


For all the details, check out the downloadable manual, linked above. Both the AR-31 and PC-TBC products offer controls governing their operation and quite possibly video signal routing. These controls are accessed through a "remote panel" that Hotronic claims to be "optional". I don't know if the PC-TBC board can be controlled through software. Its ISA connector appears to be used only as a power tap from the host computer. As I'd have a hard time believing that these TBC products can "automagically" detect color, brightness or other deficiencies, it is my belief that the remote panel is more necessary than Hotronic would have you believe.

Powering these boards in a PC may require a system with a -5V power rail, which is something that a lot of newer PCs don't have -- even if they do have an ISA slot. I got different behavior from one of mine (though nothing resembling correct operation) in a Pentium II PC and a PS/2 Model 30.

You may also require a sync/timing reference (such as a calibrated color bar generator or a known working video source with clean sync and timing signals) for the AR-31 and PC-TBC to work. If you don't have a color bar or sync generator, you might be able to use a video camera. Don't use a video tape source, though.

If you can confirm, expand upon or improve any of the information I've managed to determine, please do get in touch!

In theory at least, you should be able to hook up a video source and view or capture the time base corrected output. It's not known if the AR-31 or PC-TBC can change the electrical format of an incoming video signal: for example by converting an incoming composite video signal to S-video.

Power Up Failure of the AR-31

Both of the AR-31 standalone TBCs I've found (one I bought and one kindly given to me) have failed to power up with blinking power LEDs and a slight "tweeting" noise from the power supply's protection circuitry. The fault is not in the TBC board itself, but rather the power supply connected to it. I believe (but have not proven) that the fault lies with capacitors having gone significantly out of tolerance. Most all of these units have likely seen long hours of service and there is no cooling fan within the otherwise well vented enclosure. Every capacitor on the power supply board should be replaced to assure an effective repair. It probably isn't a terrible idea to check for other out of specification or damaged components while you're in there. None of the capacitors in my two units appeared to be obviously bloated or damaged. (I later cut open the large filter capacitor from the power supply board in one of the two units I have. I found it to be completely dried out. It looked perfectly OK from the outside.)

Being as these are switchmode power supplies, bringing the line voltage up to them gradually through the use of an adjustable autotransformer ("Variac") may result in fireworks. A conventional incandescent light bulb placed in series with the power supply input to limit current may afford some protection. A 20 watt bulb is probably sufficient. Test the repaired power supply with only a dummy load attached -- not the TBC board itself if you happen to care about it!

Left unchecked for a long enough period of time, this power supply failure may damage the AR-31/PC-TBC card. One of mine behaves erratically even when run from a good power supply and the other is in as-yet unknown working condition.

The AR-31 rear panel claims that the power supply is capable of operating from 100 through 240 volts AC at 50 or 60 Hz.

Remote Panel / Control

The AR-31 and PC-TBC both have a connection point for a "remote panel" that is claimed to be optional. Both cards also have an onboard Zilog Z80 microcontroller.

Unless there is some sort of software control method, all adjustments to the video signal have to be made with this "remote panel". I don't believe it was included with either the AR-31 or PC-TBC products. This is a wired remote control. It appears to be powered by four AAA batteries.

Hotronic AR-31 / PC-TBC Remote Panel

If you're saying to yourself at this point, "hey I've seen one of those before" ... you are absolutely right. On the surface at least, this control is identical to an X-10 HR12A PalmPad remote control.

X-10 HR12A PalmPad Remote Control
This produced a great deal of curiosity on my part. Why did Hotronic use this particular control? How closely related is it to the X-10 HR12A? Could you use an HR12A, which is probably much more commonly available and cheaper than the Hotronic remote? I'd say there is a strong chance you might. What is inside the Hotronic remote panel?

I thought you'd never ask! (Any of these pictures can be clicked to see them larger.)

Hotronic AR-31 / PC-TBC Remote Panel Internals #1

Closeup examination of the Hotronic AR-31 / PC-TBC remote panel wiring.

Hotronic AR-31 / PC-TBC Remote Panel circuit board component side.

Hotronic AR-31 / PC-TBC remote panel integrated circuit closeup.

What's readily apparent here (besides the generally very poor third world construction quality and soldering job) is the fact that Hotronic's "remote panel" really is nothing more than a reworked X-10 HR12A PalmPad remote control! Even the housecode selection wheel is present! The lone IC is a Princeton Technology Corporation PT2221, intended for use in infrared remote controls.

In case you're unfamiliar with the X-10 wireless remote controls, they all work on the same general principle: a signal in the 300 MHz radio band (the same band most garage door opener remotes also use) is emitted by the remote and later received by a "bridge" that decodes the transmitted signal and either acts on it directly (if it is the device being addressed) or re-encodes and passes it on down the power line to another X-10 device. My guess is that the FCC would absolutely love the way this remote control was modified -- it still appears to be perfectly capable of transmitting signals and undoubtedly causing headaches for nearby owners of X-10 devices.

I can't readily swear to you that the HR12A and Hotronic remote panel are precisely identical or that they emit the same codes. It does, however, seem overwhelmingly likely that such is the case given how little modification has been made. It's been a very long time since I've used any of my X-10 equipment and I don't know that I could find one of the remote modules to verify my suspicions.

Unfortunately for those of you without a remote panel, this state of affairs does complicate things rather greatly. Even in this age of cheap and capable microcontrollers, it's still not easy to encode and transmit a signal at several hundred megahertz. On the other hand, the PT2221 IC might still be available and figuring out what commands to send, and at what frequency to send them, might not be too hard. Apart from the IC, the rest of the circuitry is drop-dead simple. A more logical approach, and the one I'd hoped to see in use here, was a simple resistance based switching scheme, where different resistances would be connected in circuit and the TBC card's microcontroller would decode them to determine which function had been selected on the remote panel. Unless Hotronic really got a screamin' deal on these things, the resistance based approach seems like it would have been cheaper as well -- and there would have been no need for batteries!

I'm not sure I have anything that I can use to observe the pulse trains emitted by this IC when various buttons are pressed.

Other Thoughts and Such

As one of my Hotronic TBC cards seems not to work and the other is in as-yet unknown condition, I can't (yet) speak to how well they work.

My experience with other broadcast grade TBCs, which is admittedly very limited, has been extraordinarily disappointing so far. The units I've found either haven't worked at all, or haven't otherwise been effective at solving my problem. My planned use was to clean up the synchronization and other timing information in the signal coming from a PC video card's TV output. This signal, which looked fine to a capture card and any other video device I'd ever fed it into, was giving a Videonics MX-1 video mixer fits. Sometimes those fits were severe enough to crash the Videonics MX-1. This didn't initially seem like a difficult goal. Only later did it turn into a severe case of rocket science. (I still cannot or at least do not want to believe that grabbing a frame of video from a potentially unstable source and flushing it out with newly rewritten and precise synchronization and timing information is that difficult.)

Rather curiously, it seems that the Videonics MX-1 (which is likely to get its own page at some point in the future) does not perform any time base correction on its output unless it is presently performing a video effect, at which point it absolutely must do so.

All of this whole saga actually stems from my live streaming activities on the Internet. This isn't my first time going around and around with something in an effort to try and make it work. If you're curious about these shows, which aren't done very often at all, you may find the FAQ page interesting.

Thus far, and to me at least, it seems that the way to go if you're an end-user dealing with an unstable video source that you need to quickly and easily fix without raising your blood pressure, having a degree in broadcast engineering, being a rocket scientist, dealing with companies that won't support their products or perhaps all of those things, would be to use a MiniDV or Digital8 Sony Handycam that features the ability to capture an analog signal and digitize it over Firewire. Handycams with this function present include a very effective TBC that really does Just Work. This is what I ultimately did--chaining one such Handycam to another more basic model (only one need have the ability to perform this realtime analog conversion function) with a 4 pin DV to DV (or i.Link) cable. Picking up the video from the second Handycam's S-video output and feeding it to the MX-1 solved my problem without any of the aforementioned rigamaroles

Sony doesn't sell new-model Handycams with this functionality present any longer. You might find some on eBay or at other places where secondhand goods are sold. A few models to look for include the DCR-TRV22, 33, and 27 in the MiniDV format. Digital8 models with the same capability include the DCR-TRV520, 460 and 480. This isn't a complete list -- there are other Handycam models that have offered this functionality as well. All of these camcorders have held a fair amount of their value even on the secondhand market. Still, with some persistence you can find a very good deal on one or two.

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Copyright 2015-2018 by William R. Walsh. Some rights reserved. Your rights to reuse some or all of this material in other projects are fully detailed at the "terms and conditions" page available from the top level of this web server. In simple terms, permission is granted to use portions or the entirety of this page in your own projects, provided those projects do not contain advertising materials and no fee other than that necessary to cover reasonable duplicating or connection time expenses is charged. Such projects must also not be of an illegal, derogatory, defamatory or dangerous nature. Please don't parody my work even if the laws of your country or locale allow you to do so. Thank you. Last updated 03/17/2018.