Re: 9810 service manual Message #4 Posted by Tony Duell on 21 Dec 2004, 5:02 p.m., in response to message #3 by marais
I should be reading e-mail (and looking here) at least once a day through that period, so I can probably help you. I am happy to do it by private e-mail, or carry on posting here, the former is, however, slightly easier for long messages.
Anyway, do you have my list of initial checks? Things like checking the PSU outputs (voltage and lack of ripple), removing all that's not necessary (card reader interface, printer, I/O backplane, ROM module backplane, keyboard) and seeing what happens?
I assume you have a totally blank display. This, alas, means there could be a fault in any part of the processor, memory system, or, of course, the display board itself. Quite a bit to work through, but some areas can be eliminated easily. One thing I would do early on is look for activity on the display strobe signal on the display connector. I will guess it's not doing anything, though.
You say the processor isn't doing the things it should after INIT. OK, so what is it doing? Is it doing anything? Is the microcode program counter (accessible on the test connector on the -66513 PCB) changing. Do you have an 8-channel logic analyser? If so, you could grab the microcode addresses and see just what the CPU thinks it's doing (I have a commented source to the CPU microcode, BTW). Is it even trying to access main memory (look at the R(3) and R(6) signals (my names, my schematics), one is read, the other is write)?
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