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IBM PS/1 model 2011 - trying to bring it back to life

alank2

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Starting a new thread because the old one makes it sound like it is about the power board and probably many people aren't familiar with the power board. I think the power board is fine. Voltages are fine.

Keyboard plugged into it blinks it lights at power on, so it is getting power.

The system was working, then it froze, when I power cycled it after that, it never came back to life.

I've looked at the two oscillators on the board (48M, 40M) and both are running.

I don't see any activity on the ROM's on the A0 pin.

I don't see any activity on the data pins of the parallel port which I think should have post codes.

I've tested the RTC and it doesn't seem perfect, but it does run sometimes so I don't think this is the issue (because I don't see the system even trying to do anything with A0).

Reset is high.

Any ideas on what to check next?
 
If the keyboard blinks the three LED's and then go out that means the PS/2 port was able to successfully initialize.
Is the Dallas module new or known good? It's possible a flat battery in that will never allow it to initialize the CMOS properly and I distinctly remember from mine that it was often hard to keep it to retain settings even between warm reboots.
 
It isn't the stock IBM keyboard that came with it, but another IBM keyboard. The 3 LED's do come on and go off, but does that happen just because it has power and the internal microcontroller does it? Or something from the PC makes it happen?

I don't know what to say about the Dallas module. I did drill it and disable the built in cell and then soldered up a cr2032 to it. I even made up an AVR project to communicate with it and it mostly works. Sometimes it resets the time numbers to 0x66 though and sometimes when trying to read all registers it gives 0xff (I think it isn't responding), so it is suspect. I saw a video where this machine did not have video until the Dallas issue was corrected, so I wondered if that was the problem and I've got some new modules coming Monday to try.

None of that explains why I don't see any activity on the ROM BIOS pins. Shouldn't I see tons of activity on A0 as it is fetching bytes? Or the parallel port, I've seen the BIOS and it looks like it is outputting a post code to the parallel port data, but I see nothing there either.

Thanks for helping!
 
The fact it died during use and froze in place to me indicates there's been a major component failure and I doubt the Dallas module has anything to do with it. The fact that even on a cold start you are still seeing no bus activity means whatever failed is still in a failed state and whatever that might be is holding up everything. I really don't know where to begin. Something's preventing the CPU from loading the BIOS.
 
I guess I can try to see what pins I can probe on the CPU, it looks like a QFP, maybe that will yield something.
 
The CPU CLK pin has no signal. It looks like it is coming out of the 64F1330 IC to the right of it.
 
No clock will absolutely mean nothing works. 64F1330 is an IBM ASIC. You better hope it's something supporting that chip which has failed because if that has gone bad that's all there is.
 
I know. I've checked the two oscillators on board and they are both working so it isn't looking good.
 
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