Electronics > Repair
HP 4145A Error A01
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picburner:
It seems that the "A01" error when cold is endemic to this instrument, my 4145B does the same thing but once warmed up it works perfectly without any problems.
ZhuraYuk:

--- Quote from: picburner on December 04, 2024, 05:05:54 am ---It seems that the "A01" error when cold is endemic to this instrument, my 4145B does the same thing but once warmed up it works perfectly without any problems.

--- End quote ---
From the manual it looks like I should wait 40 min for the instrument to be functional and that is normal behaviour? Does not seems like HP thing.
The second notice states that A01 will be shown if device is in test mode because of DIP switch settings. S1 switch is located in IO bus and sets some bits on it.

TERRA Operative does your show the same behaviour when cold?
TERRA Operative:
I have never seen that error on my 4145A or 4145B that I remember.
I'll boot the 4145A up again and see. (And the 4145B too if I can actually find my HxC floppy emulator, if that would help)
Maybe I'll stick it outside in the cold for a bit and see if that does anything. :)
ZhuraYuk:
So, one step closer. After replacing U33  74LS245 with much slower 74HC245 board starts initialization immediately and passes all self test steps but never finishes it. It starts it over and over again. So it is 9ns vs 15ns, I guess, I need to find something like 11-12 ns delay.
ZhuraYuk:
Can someone give me a hint what is going on ? When I remove U33 the board initialize normally and stops at point of AD circuit communication, which is normal because U33 is just a buffer for AD circuit and nothing else.
When I install new U33 the board is not initializing at all, not even self test! Something from AD circuit is spoiling the communication?
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