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Compaq LTE 8086 repairs

befi

New Member
Joined
Oct 27, 2023
Messages
1
Hello


I am currently in the process of repairing a LTE 286 and the damage is almost catastrophic: Stuck HDD bearing, stuck HDD arm, broken floppy belt, misaligned floppy head (after replacing the belt), faults (due to corrosion): no working backlight, no power switch, malfunctioning keyboard controller, broken memory traces on the GPU, and at least 10 more dissolved tracks that I had to replace with patch wires.

So far I could fix almost all of the issues (which took an insane amount of time) but there is one issue I am really really struggling with. The machine reports a "610 - External storage module failure" most of the time after powerup. In roughly 1 out of 10 tries the machine succeeds and boot without any issue.
According to the manual the 610 message appears if the external storage module is connected but not powered up.

2023-10-27-211534_1021x629_scrot.png

So my theory is: The "external drive present" signal is corroded as well and therefore has some undefined voltage which sometimes is interpreted as 0 and sometimes as 1. The issue is, since the track is corroded, I cannot trace where the signal goes. I brushed the whole board with a copper brush that was connected to a continuity tester but had no luck whatsoever. Externally applying voltage to the pin also did not change the behavior (when powered up, the voltage is undefined and the connector pin seems to be high-Z).
Logically deducing to where the signal should go is also tricky. The other signals of the external storage connector end up all over the place. Most are connected to the floppy controller IC, some to the large ASIC, some to the small ASIC, others to a differential driver IC...

Honestly, I feel a bit lost without knowing where the signal is supposed to go. Do any of you have by any chance a board still lying around and would be willing to trace that signal for me?

Thanks and best regards,
befi.
 
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