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Calculator Repair KnowledgeBase

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The following is a list of specific cases that I encountered during my calculator repairs. I make no claims as to the suitability of the methods presented here in repairing other calculators; these methods did the job for me for specific machines, and I thought that the experience might be useful to others, that's all.

1. Bad transistor in HP-33E DC-DC converter circuit
2. Bad diode in HP-25 DC-DC converter
3. Dead HP-55
4. Bad transformer in HP-33E DC-DC converter circuit
5. Bad chip in HP-33E
6. Missing pixel rows in HP "Topcat" printout
7. Dead "Topcat" logic board
8. Woodstock 'C' memories
9. SR-52 consistently misreads cards
10. Bad digit driver in a Novus 6025
11. Bad digits in a Texas Instruments SR-10
12. Bad memory in TI-66 (case 1)
13. Bad memory in TI-66 (case 2)
14. HP-67 can write, but not read, except at low battery voltage
15. Dead segment across HP-67 display