View Full Version : IBM PS/2 model 77 schematic

October 27th, 2017, 08:39 AM

I'm looking schematic for an IBM PS / 2 model 77. The computer is in very bad shape and I'm trying to revive it.
Anyone know if there are schematics and if so from where they can be downloaded?

Greetings and thanks.

Some photos

October 27th, 2017, 01:28 PM
what's the part number or FRU on the system board?

might have a replacement... =)

October 27th, 2017, 01:41 PM
Not trying to be a "wet-blanket", but if the two photos are a representation of the entire system, then it looks way too far gone to justify reviving. PCB traces are likely compromised in many locations and you'd have a very difficult time repairing them without special soldering equipment to remove the components (to get to the corrosion/trace runs that are likely broken). If the board is multi-layer (not likely in that old of a system), then repairing that would virtually be impossible.

October 30th, 2017, 07:17 AM
Thank you for your answers. I'm going to change the capacitors and test if it turns on. If the computer does not turn on, I'll keep it in the trash :)
The board is missing 2 capacitors, does anyone know the values?

December 6th, 2017, 12:40 PM
I'm trying to revive this computer.
The PSU is dead so I am using an ATX PSU.
In the P1 connector I send 5v and GND.
On connector P2 I send, pin 1 12v, 2 none, 3 none, 4 none, 5 -12v, 6 gnd, 7 -5v
Is the connection correct?
Is it correct not to send any signal for pin 3 and / or 4?

I turned on the ATX PSU but the 77 does not give a signal of life. No Beep, no video.
Any suggestions?