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Help with HP-67
06-06-2019, 02:26 PM
Post: #2
RE: Help with HP-67
(06-06-2019 01:34 PM)twoweims Wrote:  I recently acquired a non-working HP-67.
It appears that there is a short circuit between Vbsw and ground.
When I power it up from the battery terminals with an external power supply my power supply voltage just collapses. The low battery LED blinks momentarily as the voltage drops, which I would expect.

I have isolated the card reader and the logic board and tried to power the keyboard/display board alone and the fault persists.

Vbsw does not seem to do much on this board other than provide Vcc to the cathode driver and the low battery LED. I may be missing something because I don't have a good schematic. I am suspecting a problem with the cathode driver.

Is there a service manual for this calculator. I have the MOHPC Thumb drive and I don't see one on there.

If anyone has worked through this particular problem before, I would appreciate any advice.


Maybe Tony's schematics can be of help.


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Messages In This Thread
Help with HP-67 - twoweims - 06-06-2019, 01:34 PM
RE: Help with HP-67 - Massimo Gnerucci - 06-06-2019 02:26 PM
RE: Help with HP-67 - teenix - 06-06-2019, 04:50 PM
RE: Help with HP-67 - Zaphod - 06-07-2019, 09:31 AM
RE: Help with HP-67 - twoweims - 06-07-2019, 12:47 PM

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