Assorted Repair Hints

Contents:

[Document Version: 1.00] [Last Updated: 3/26/96]

1. Repeat Home Stereo with Blown output IC

One of the principal tenets of Kinsler Hi-Fi Service was:

The Customer is Always Wrong.

I doubt that it's a matter of volume or bass: these things will limit themselves pretty well. What's happening is that the guy is short-circuiting his speaker wires. He's either got another set of speakers that he uses for parties that he's not telling you about, or he has a set out on the porch with which to serenade the neighborhood. There's a bum splice in the wire that he doesn't know about, doesn't care

They like to horse around with the speaker arrangements whilst under the influence, particularly at parties. Or his kids borrow the thing and take it to a friend's house and hook it up to the Christmas lights to try to watch them flash with the music. I am not making this up: I'll tell

The only way to protect yourself is to solder a couple of appropriately-sized fuses in series with the speaker lines. Put 'em inside the case, and SOLDER them directly in. If you put them in a fuse holder, the customer or his minions will pull them out, replace them with 25 amp car fuses, blow out the IC, then replace them with your 1 or 2 amp fuses from Radio Shack, and claim ignorance of the whole thing. Again, I am not making this up. When I soldered fuses in, I'd get the sets back with what were supposed to be my original fuses taped in with scotch tape. Once someone used a Band-aid. But generally the solder keeps them out of there. It's best, in fact, not to volunteer the fact that the fuses are in there at all. If there are speaker fuses in

The fuse size is a bit critical, of course. You can figure it out from the power and speaker impedance, but generally 1 or 2 ampere fuses are okay for anything that's made of plastic. Use regular-blow fuses, not slow-blow. Soldering fuses is easier if you use the Chinese ones that MCM sells--they're already soldered on the ends. Expect to occasionally lose a fuse when you're soldering it in, but you get good at it fast. If you use fancy fuses like Buss or Littelfuse, you have to file off the nickel plate from the ends to expose the brass. That way, you can tin it quickly before the fuse wire detaches from the inside of the fuse. Enclose the fuse in a piece of clear, non-heat-shrink tubing. Or often you can solder one end of the fuse directly to the circuit board or to the speaker connector. You have to use some imagination. When the device comes back with the speaker fuses blown, just replace them at no charge--it's a fast job, and you'll know what's going on. Then you can start quizzing the customer about his Experiments In Stereo Speaker Wire Science Whilst Intoxicated. My favorite defense was, "No, I did NOT

Kinsler Hi-Fi specialized in crummy stereos for many years, and I put a pair of speaker fuses (and a power fuse, when that was missing) in just about everything that came in. I used more fuses than anyone else in New

This article was processed by Filip Gieszczykiewicz [mailto]. The most recent version is available on the WWW server http://www.repairfaq.org/ [Copyright] [Disclaimer]