Free Abandoned HP 3478A 5-½ Digit DVM Repair

We repair a classic HP 3478A 5-½ digit voltmeter, and admire its ultra complicated A to D converter. HP Multislope II ADC patent: https://patents.google.com/patent/US4357600A/en Ian Scott Johnston video on HP 3457 backlight mod: https://youtu.be/oEu7nqOkKxo Blacklight display mod: https://www.eevblog.com/forum/testgear/another-hp3478a-backlight-display-hack/ LCD protocol reverse engineering: https://www.eevblog.com/forum/projects/led-display-for-hp-3457a-multimeter-i-did-it-)/msg1347268/#msg1347268 OLED mod: https://www.eevblog.com/forum/testgear/hp3548-hp3457-oled-display/ Ken Shirriff's Nanoprocessor reverse engineering: http://www.righto.com/2020/09/hp-nanoprocessor-part-ii-reverse.html Ken Shirriff’s reverse engineering of the hybrid in Marco Reps’ HP 3458: https://x.com/ken ...