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amadama
September 11th, 2013, 10:41 AM
Hi everyone,
Just picked up a nice looking Kaypro II. It booted up from the boot disk just fine and then the screen started getting slowly dimmer. After about two minutes a very loud "POP" was heard, a nasty smell was emitted (like a burning smell) and the screen came back up but is now vertically rolling.
I could use some tips on troubleshooting this. Blown capacitors?
Thanks,
Alex

MikeS
September 11th, 2013, 10:48 AM
Blown capacitors?Sure sounds like it; I'd start with a visual inspection of the display board, they're often quite obvious.

Al Kossow
September 11th, 2013, 10:51 AM
I could use some tips on troubleshooting this. Blown capacitors?


Likely suspect, in the vertical deflection section
Probably a bypass or filter cap on the power side shorted, since it took the horizontal/high voltage down as well.

amadama
September 11th, 2013, 11:40 AM
Thanks guys.
I'll give it a day or so to discharge and I'll crack it open and take a look.
Thanks,
Alex

Stone
September 11th, 2013, 11:58 AM
A ground strap to the HV terminal will discharge it immediately.

galael
October 27th, 2013, 08:51 AM
Hi everyone,
Just picked up a nice looking Kaypro II. It booted up from the boot disk just fine and then the screen started getting slowly dimmer. After about two minutes a very loud "POP" was heard, a nasty smell was emitted (like a burning smell)

You very likely blew one of the rice paper caps on the power supply board. Exactly the same thing happened to me. They are easy to replace. Depending on the model of your power supply board there are only three or four of these caps so I recommend you replace all of them. These two website show details on how to replace them:

http://www.classic-computers.org.nz/blog/2010-01-15-fixing-blown-caps-on-kaypro.htm
http://antediluviandesigns.com/kaypro4.html

Galael

amadama
October 28th, 2013, 02:25 PM
Thanks I will take a look.
Haven't cracked open the Kaypro yet. Setting up a new work area in the basement (family wasn't too happy with me working on the dining room table, made it very difficult to have dinner and the soldering iron used to get in the way...)