• Please review our updated Terms and Rules here

PCjr schematics?

G

geoffm3

Veteran Member
Joined
Oct 9, 2009
Messages
1,272
Location
Huntsville, AL
I've never owned an IBM computer before (plenty of clones of course), but I have an opportunity to acquire a non-functional PCjr in the box hopefully this week. I haven't been able to find schematics for the thing on line so far. Anyone know where to get them?
 
That was my first stop, but the Documentation area didn't have the tech ref -- maybe I missed it somewhere else on the site?

In any case, Mike's PCjr site is required reading for new owners of a PCjr :)
 
Alright... I'm now in the possession of the PCjr!

The machine powers up, beeps twice and then displays nothing through the composite video jack. The computer's purchase came well documented, and oddly enough, it has apparently had this trouble before. There is a repair ticket (from ComputerLand!) and the problem statement says, "fan comes on but nothing on screen" and the resolution was to replace the motherboard, under warranty (retail price $450).

It also has invoices for when the computer was purchased and what was included. The parallel port attachment they paid $88.11 for, the Enhanced model PCjr was $999 (January '85), and came with PC DOS 2.1 and Cartridge BASIC.

I haven't tried using the PCjr color monitor with it, just my TV through the composite video jack to troubleshoot.
 
Hopefully the PCjr monitor will show the IBM logo and then some error codes. If you get no image through either port, then something is seriously wrong and it's going to take the PCjr Hardware Reference Library to troubleshoot it. (The tech reference is good at explaining the entire machine, but it's not a hardware repair reference like the Hardware Ref is.)
 
Trixter said:
Hopefully the PCjr monitor will show the IBM logo and then some error codes. If you get no image through either port, then something is seriously wrong and it's going to take the PCjr Hardware Reference Library to troubleshoot it. (The tech reference is good at explaining the entire machine, but it's not a hardware repair reference like the Hardware Ref is.)
Click to expand...

No dice with the PCjr monitor... no video on that either.

I had a look around on the motherboard, and the only thing that stands out is there is a resistor that is clipped near the composite video connector (right next to a 7404). I can't believe IBM was so cheap/secretive to not print the reference designators on the PCB! :) The schematics from the tech reference PDF aren't legible for that resistor.

Also, anyone know what the two jumper connectors are for near the back of the board to either side of the left bank of connectors?
 
You must log in or register to reply here.
Back
Top