I had dysfunctional switches on a heating system timer. The trade advice since replacements were unobtanium was open them up and clean the contacts with switch cleaner. The contacts were two "gold" plated pads bridged by pressing down conductive plastic with a textured finish : same design as the keyboards. The cotton buds lifted a lot of black "tarnish" (probably airborne contaminants) from the contacts. Went from a few working, a few intermittent and some totally dead, to all 16 working all the time. Have to see if they last another 12 years before failing. I infer that cleaning off the contaminants is 95% of the solution. I doubt the solvent used is especially critical.
Martin -----Original Message----- From: cctalk [mailto:[email protected]] On Behalf Of Fred Cisin via cctalk Sent: 25 May 2022 16:33 To: General Discussion: On-Topic and Off-Topic Posts <[email protected]> Subject: Re: The TRS-80 Journey Continues On Wed, 25 May 2022, Bill Gunshannon via cctalk wrote: > Another question for the masters here. > I just tried to revive my Model III. More than half the keys don't > work anymore. What is the conventional wisdom on cleaning these old > TRS-80 keyboards? Is compressed air usually enough? Can I spray the > switches with something like DeOxit safely? I expect when I go to > revive my Model I's they are likely to be in the same state. A really stupid suggestion: (cleaning the key mechanisms makes more sense): More than a quarter of a century ago, I revived several of my TRS-80's. None of the keys worked on one keyboard, and many of the keys didn't work on another. But, I noticed that repeatedly pressing an intermittent key made it work reliably, and repeatedly pressing a "dead" key got it working! I had a Rochester Dynatyper and a KGS-80, which were the two most common versions of a box of solenoids to place on top of a typewriter to convert it into a printer. Those came out when there were no cheap printers. There also existed a box, made by an outfit in Walnut Creek, to put UNDER a Selectric that pulled down on the keys, but I neever had one of those, and that was ONLY for Selectric, whereas the Rochester Dynatyper and the KGS-80 worked on ANYTHING with a normal keyboard, even a Merganthaler! I remember once at the West Coast Computer Faire, somebody showed a prototype of one that used fishing line and pulleys to work the carriage return of a MANUAL (non-electric) typewriter - every successful carriage return got a round of applause. I used the Dynatyper and the KGS-80 to "type" a few hundred pages. The TRS-80 keyboards came back to life! -- Grumpy Ol' Fred
