Re: MacXL - Crash

From: James MacPhail <gg__at_email.domain.hidden>
Date: Wed, 19 Apr 2006 14:33:52 -0700

>I did perform all tests with the result now being:
>2 beeps and a checkerboard background, ejects diskettes when inserted.

The floppy drive won't be useful until you get past the self-test, which requires a working display. However, the fact that it ejects disks and beeps probably means the I/O and CPU boards are working to some extent.

Just to be clear, when you say "checkerboard background", you mean the display still doesn't show anything useful, correct?

If so, then I think the problem must be one of these:

  1. CPU board problem
  2. Memory board problem
  3. connection between CPU and Memory

Usually, (c) is the problem, hence the first step of cleaning the edge connectors.

Since you started working on it, it seems that the display has changed from random to checkerboard. This implies to me that you are making progress, and perhaps you should do some further cleaning.

When it failed 8 years ago, perhaps there were other symptoms... do you recall if it failed completely or intermittently, and if there was any noise, flash, or odour associated with the failure?

Is your memory board the stock Apple 512K one? If not, then it might be possible to change its configuration to aid troubleshooting.

Lacking further info, this would be my approach:

Remove all the boards, and carefully inspect the sockets that receive the cards. Look for bent or broken fingers, which will be obviously different from their neighbours.

Assuming you find nothing wrong:

Reassemble with I/O, CPU, and 1 Memory board (no expansion slot cards). If that doesn't work, move the memory board to the other MEM slot. If that doesn't work, repeat with a different memory board (if you have one).

If that doesn't work, then I think solving this problem will require either some fancy equipment (logic analyzer), a working Lisa to swap parts with, or some known-good boards.

Perhaps someone on the LisaList is nearby and can help isolate the problem by lending some good boards or testing your boards in a working Lisa... where are you located?

HTH, James

James MacPhail                   "Think not of engineering as art,
uo957_at_email.domain.hidden                 but of art as engineering"
Sigma Seven Systems Ltd.
james_at_email.domain.hidden        <>

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