I've got a 80286 PS/1 that a friend gave me that is having some odd issues.
First, the keyboard didn't work, but the computer did boot with a different ps/2 keyboard.
But, then it locked up and when I powered it off/on, it never came back again. The monitor turns on, but the system won't post or show anything.
I checked the monitor voltage out and it is 37 volts DC. I then opened up the main system and there is a power supply card that converts that to the voltages needed for the system. I can see a -11 something, +11 something, and a +5.1 volts on some of the various pins on this card, but I don't have the pinout so I don't know if all of the signals are correct or not. If I try to read the + side of some of the electrolytic capacitors on the mainboard, they are near 0V, so that must be why it isn't working. I've pulled the modem, floppy, and hard drive with no differences so I have to assume it is something in the power board that isn't working properly. Does anyone have the pinout for it?
I found a manual, the output of the power card is good. I found a different capacitor on the motherboard and it does have 5V, so perhaps the first cap I found is used for something different (its + side is ground and its - is -3V).
So the issue is no video, no beep, etc. It _was_ working. Any tips on what I should check next?
First, the keyboard didn't work, but the computer did boot with a different ps/2 keyboard.
But, then it locked up and when I powered it off/on, it never came back again. The monitor turns on, but the system won't post or show anything.
I checked the monitor voltage out and it is 37 volts DC. I then opened up the main system and there is a power supply card that converts that to the voltages needed for the system. I can see a -11 something, +11 something, and a +5.1 volts on some of the various pins on this card, but I don't have the pinout so I don't know if all of the signals are correct or not. If I try to read the + side of some of the electrolytic capacitors on the mainboard, they are near 0V, so that must be why it isn't working. I've pulled the modem, floppy, and hard drive with no differences so I have to assume it is something in the power board that isn't working properly. Does anyone have the pinout for it?
I found a manual, the output of the power card is good. I found a different capacitor on the motherboard and it does have 5V, so perhaps the first cap I found is used for something different (its + side is ground and its - is -3V).
So the issue is no video, no beep, etc. It _was_ working. Any tips on what I should check next?
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