HP9100B repair

[isanchez]

Hi,
I have an HP9100B to repair (well, to try to repair). I have seen a huge amount of information avaliable in this forum and many documentation from Tony Duell and others. Thanks to all for your contributions! My HP9100B doesn't look very well externally, but internally looks pretty well (Clean and not evident burned components).
The display doesn't respond when turned on.
The error light turns on sometimes when I touch de keyboard.
A couple or three times, when I was trying to turn it on, the display showed figures with not so much sense.
From the information I have seen my conclusions/next steps could be:
- The Power source is working (fine). It is not frequent that it fails. Even the capacitors.
- The CRC tube works.
- I should remove the Card reader and check. Even the keyboard failure can cause the problem.
- The most frequent problems come from transistors failures. One single defective transistor can cause the problem. Am I right? Hence: check the transistors, but there are hundreds...any recommendation about where to start?

It is a pity IMMO, to have a big amount of disconnected information. Maybe it would be of help to create some kind of "checking protocol" to try to identify the problem of the HP9100Bs.

Thanks in advance to all.

Kind regards

Ignacio

[TASP]

Do NOT do this with out concurrence from others, but if there is a consensus you 'probably' have a bad transistor (or three), a technique I have had some success with is freeze mist.

I would DEFINITELY want to hear from others that have fixed a 9100 and employed this technique before trying it.

Hundreds of transistors sounds like a nightmare to diagnose without extensive supportive materials from HP. Does the MoHPC collection have service manuals, diagrams ?

[isanchez]

Hi Tasp,
You mean, the way is not to check each transistor individually with a tester? It can be tedious, but it is just a matter of patience...This makes things quite difficult, at least for me. I have never heard about the procedure you mention. Can you give me some details and I shall search in Google?

Thanks and kind regards,
Ignacio

[isanchez]

Hi again,
As far as I know, and correct me if not, the official documents are related to the analog part. There are very helpful diagrams made from a reverse engineering process by Tony Duell, probably the man who better and deeper knows these calculators...and others:-) I repaired an hp46 thanks to him.
Kind regards
Ignacio