Jerry Walker has published quite a few repair videos about two HP 9100B calculators and 9120A printers on YouTube. Take the time and have a look, interesting stuff and you can learn a lot. Maybe, it even helps in your own repair attempts.
HP 9100B #1
- Repair Part 1
- Repair Part 2
- Repair Part 3
- Repair Part 4
- Repair Part 5
- Repair Part 6
- Repair Part 7
- Repair Part 8
- Repair Part 9
- Repair Part 10
HP 9100B #2
HP 9120A #1
- Repair Part 1
- Repair Part 2
- Repair Part 3
- Repair Part 4
- Repair Part 5
- Repair Part 6
- Repair Part 7
- Repair Part 8
- Repair Part 9
- Repair Part 10
- Repair Part 11
- Repair Part 12
HP 9120A #2
- Repair Part 1
- Repair Part 2
- Repair Part 3
- Repair Part 4
- Repair Part 5