HP 86: Strange Error

[Michael Fehlhammer]

Thank you for your answers!

Since I have no rom drawer installed ( and receive the warning anyway), I might check - like Bob suggested - if there are additional roms installed internally. But - who should have been so stupid to install the wrong kind of rom module inside the case? Not so likely, isn't it? Hmm.
Although I have no clue about hardware, I am afraid Bob's guess "some signal lines on a board are damaged" seems to be a good explanation for this behaviour, unfortunately.

I have got a second computer of the same kind (86A), which works fine.
I could use it for comparison, if I had an idea what should be compared.

In order to plug in the diagnostics rom, I'd have to transfer it onto my PRM-85.
This should be feasible.
Is there a documentation available how to use the diagnostics rom? Probably I should get the HP 86 service manual?