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+--- Thread: HP 9820A Desktop Diagnosis HELP (/thread-3112.html)
HP 9820A Desktop Diagnosis HELP - aj04062 - 02-16-2015 12:59 PM
My 9820 seems to have developed an issue since I last turned it on. It was working before Christmas.
When powered up I have no display. I have checked the power supply voltages and they are fine. Curiously this unit has a Mathematics and Peripheral Control modules. With the Peripheral Module removed, it does not respond at all to any keyboard entry. With the Peripheral Module installed, 0 will register as will Program "LIST". The response from hitting this key is "NOTE 16" which is CONFIGURATION ERROR per the note codes.
To get this going initially last year I pulled all boards per Tony D's excellent write-up. I discovered the printer was an issue (pulling down the power supply) as it was the last item to re-install. I plan to repeat this, but thought someone might have a suggestion based on these symptoms.
There is on thing that might have created the issue. A month ago I had a washing machine malfunction that leaked water from the 2nd floor into the utility room where this and other vintage desktops were stacked. I don't know if this one took on water drips or not, as I don't recall if it was on top. It is surely dry by now, but perhaps there was some residue (soap) in the water that has compromised a contact. It was not flooded or underwater!
Again, any thoughts or ideas are appreciated.
RE: HP 9820A Desktop Diagnosis HELP - aj04062 - 02-16-2015 02:18 PM
UPDATE:
I have inspected edge connections and cleaned a few in the memory box and on the CPU cards. Sadly now, I get no response from the machine.
I double checked and cleaned all connections. I then swapped processor boards from my running 9810 and nothing changed. I think it may be an issue within the memory box. Does anyone have the capabilities to diagnose the fault? I don't. I don't own a logic probe or logic analyzer.