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HP-97 keyboard problem
02-19-2016, 10:07 PM (This post was last modified: 02-19-2016 10:18 PM by Dave92F1.)
Post: #3
RE: HP-97 keyboard problem
[Edited to correct stupidities...I am not always the sharpest tool in the shed.]

Hm. I checked again. Here's the complete list of keys that don't respond:

A B C D E f RCL DSP CLX ENTER 1 2 3 EEX CHS

The FIX and divide keys work OK.

So, you're right - it's the whole rightmost column in the schematic on page 4-23 of the service manual. Which looks like it connects to pin 1 of connector P1.

Do I have a bad cathode driver chip (U1) ? Is that something that can be replaced (I'm up for desoldering/resoldering a 22 pin DIP)? Or is it made of unobtanium?

Or - is it perhaps the mess of transistors and diodes in the lower right corner of page 4-15 (the logic board schematic). That seems to show Pins 1 and 2 of P1 both connected to C6 - if so, why is only the rightmost column affected (and not the one next to it?)
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Messages In This Thread
HP-97 keyboard problem - Dave92F1 - 02-19-2016, 09:20 PM
RE: HP-97 keyboard problem - Dave92F1 - 02-19-2016 10:07 PM
RE: HP-97 keyboard problem - Dave92F1 - 02-19-2016, 11:04 PM
RE: HP-97 keyboard problem - rprosperi - 02-19-2016, 11:10 PM
RE: HP-97 keyboard problem - Dave92F1 - 02-19-2016, 11:15 PM



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