ok... a bit more time now....
Before you do anything, get all your (4) parm files saved off. in duplicate.... ;-)
Make sure you have all your unlock codes someplace.
You may want to just get a new CPU batt while you get this taken care of.
I explain how to replace all the caps in the PC Low-Voltage power supply. This is the +5 +12 -12 and it has the power cables that run to the processor boards. (btw/ for RS2332, and this C40 circuit the -12 is derived and not from that PC supply. There is another post I did not find. Its from around the time of mine, and w/ another guy w/ the same issue. He just bought a PC replacement supply for $40... that is my suggested course in the near future. Forget yanking all those caps and making smoke for $40.... just buy it.
Some posts in the web note to TRY the low voltage supply first for the repeating chars, (as well as unplugging the keyboard ribbon) ... BUT... neither fixed my issue, or the other guys. It's just part of making good clean CPU and digital power for $40 for your older system.
anyone w/ PCB board experience should be able to replace that cap for you. took me 10mins. The copper traces on the board from/to the cap are very delicate. a solder point will end up pulling up the wire traces if you leave it on too long. Get some #30 gauge wire. Each side of that .27c cap goes to a spot or a pin on the RS232 chip which you can just jumper wire to if needed .(if you ruin the copper traces). 30 gauge solder is all you need. Dont try this w/ some mongo 1/8 round hunk o' solder rope.
Getting the dang board out and back in will be the hardest part. Also, buy a static-wrist strap protector. Pack of 3 is like $5 on amazon. Use it.
Take pictures and Mark ALL of your connectors w/ marker as you take them off if you cannot clearly read and verify the label on the wire or end for it's location.
Good luck.
Excellent post! Thanks for the directions, however ambiguous the actual cause of it was - I will work at some the fixes you done to yours.
- Capacitor C40
- PS...? (which one idk yet lol)