Dead Keyboards

[LuckyBill]

Hi, I've just run into a problem I need help with. I managed to pickup about 10 vintage keyboards that have been in storage for over 12 years. These are the KBs with the Big Din (5 pin) connectors. In testing them out with an old untested 386 computer, 3 of them were either dead or the computer "killed" them, they no longer work. After the 3rd KB died, I scrapped the computer as it also had a few other issues. I have been testing an equally vintage 286 computer which has been working, but in the last few days, it has "killed" a couple more KBs that it had successfully worked with for a few days.
My question is, is there anyway to "fix" or restore these broken KBs? I am about to scrap the 286 as I cannot afford to lose any more KBs. Suggestions, ideas will be appreciated.
Thanks, Lucky Bill

[jsheradin]

If they're spontaneously dying some possibilities include degrading foam (if they're KT/BTC) or failing electrolytic caps. It could be any number of causes.

Do you have any more info about the keyboards? Model numbers, pictures, etc. would be helpful. Also how did you determine they are 'dead'?

Don't throw out any more 286 era computers. It would have to be a pretty catastrophic hardware issue for a computer to actually kill a keyboard.

[Findecanor]

If it's a big DIN plug, the protocol could be either XT or AT ... or even something completely different such as Amiga or a terminal keyboard or unusual Japanese home computer. If it is the wrong protocol then it will of course not work.
The layout is often a tell, but there are exceptions. Some PC keyboards even have an XT/AT switch.

The computer must be OFF when you connect the plug, otherwise you could fry the keyboard's or the computer's electronics. Neither XT or AT is hot-swap.
Therefore, an adaptor to USB is quite useful because that allows you to hot-swap keyboards by hot-swapping the USB plug.

If a keyboard was broken in the first place before you connected it, it is most often electrolytic capacitors that have leaked or dried out. This can happen even with keyboards in otherwise pristine condition.

[LuckyBill]

Ok, here's some more information on my issues. The computers I'm using are ATs. And I will admit that I have been doing hot-swaps to change KBs. I did not realize that I should not do this with these vintage KBs. The KBs are:

Compudyne, KPQ-E99AC, FCC - EW4KPQ2479A (2 of them)
Compaq, DeskPro 286 (no other info)
BTC, Professional KB Series, BTC-5060AT, F21, FCC E5X5R5BTC-5060AT
Comptech (Keytronics), EP3435XTAT, has the AT/XT switch on it, it was set to AT)
Jujitsu, FKB4700-101, FCC C9S4D5KB4700

Note: the Comptech and Jujitsu KBs died while being used and after I had done a restart on the 286 computer.
The others died when they were plugged in while the computer was up and running the 386 computer.

I determined they were dead because there were no lights on on the KB and nothing appeared on the monitor screen when I hit a key. I do not have another system hooked up right now or I would retest them on another vintage computer. I have an Epson Equity I+ computer that accepts the Big DIN type connector that I could use.
I cannot say for sure if all the KBs were in working condition, but I cannot believe that the first few that I tried were all bad. This was to be my initial testing of these KBs.

Thanks for your info and maybe this additional information will help in seeing what I've got going here.
Lucky Bill

[Muirium]

Try an active USB converter. (Not a cheapo passive USB cable.) If that doesn’t work: replace those electrolytic caps. These boards are almost certainly still working if treated right. Hint: NOT hotplugging!