Electronics > Repair
HP 4145A Error A01
ZhuraYuk:
So, the first time I turned on the device, the error was not present. But next time the A01 is displaying constantly. I checked everything (voltages, oscillograms) that is possible. Went through all Test Sequence Flow Diagrams from OSM for various boards. All tests and LEDs are showing that there should be no errors. Packets of data SRD SCD and SCK are flowing nicely between A2 and A3 boards after self test button is pressed. Still, error A01 means basically that there is a problem in communications between A2 and A3 boards (optocouplers are ok). Cant figure out yet. Any help or ideas are much appreciated.
ZhuraYuk:
I narrowed the issue so now it is obvious how to reproduce it. When device is cold it shows the A01 error but once it is turned on and heats up for 30 seconds, after you quickly turn off and on again the error will gone and device passes self test.
Can someone with device post oscillogram of how RESET signal looks like? This is A12 DC power supply board TP8, reference to chassis ground.
TERRA Operative:
I'll dig mine out in the next few days and hook up the scope.
ZhuraYuk:
Got better understanding with time. The exact reason of the error is A3 board initialization delay when cold. The 4 didoes on board are blinking all the time, means that board is not doing any internal tests. A2 boards expect immediate response but A3 is not initialized thus error appears. Once it heats up for 30 seconds, the initialization is immediate. I tried to heat up device without faulty board inserted but it is not helping, this means that A3 board need to be hot itself.
Also tried to heat with hot air gun ROM, CPU and ASIC ICs, but it is not helping. Still, the board needs to be inserted and heated up in the 4145A itself.
TERRA Operative:
Did you still need any measurements taken?
Have you checked the voltage rails for voltage and ripple?
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