Author Topic: HP 85 calculator repair help  (Read 795 times)

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Offline GianniTopic starter

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HP 85 calculator repair help
« on: July 01, 2023, 11:19:16 am »
My HP85 had some disaster and now I am trying to fix the power supply board.

Currently, the problem is that Vcc = 6.5V instead of 5V. Maybe that it caused other catastrophes but to understand I must first fix the power supply.

MY PROBLEM is that my PSU board is DIFFERENT from the manual. Has somebody the schematic diagram of this board? I would be very grateful.

Thanks
 
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Offline cruff

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Re: HP 85 calculator repair help
« Reply #1 on: July 01, 2023, 12:38:23 pm »
There are lots of HP series 80 enthusiasts on the hpseries80@groups.io list who can be of help. It would help to know which specific model (A or B) of the HP85 you have. The HP Computer Museum http://www.hpmuseum.net/collection_document.php has many manuals for HP products including the series 80 systems if you haven't yet found them.
 

Offline GianniTopic starter

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Re: HP 85 calculator repair help
« Reply #2 on: July 01, 2023, 04:28:39 pm »
thanks, I will follow your suggestion
 

Offline GianniTopic starter

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Re: HP 85 calculator repair help
« Reply #3 on: July 09, 2023, 06:46:46 pm »
Just to leave a record for other interested. My is a "B" model, so I had to use the right manual. This power supply requires a minimum load on the +5V (300mA) to work. So no disaster, everything was OK and my HP-85B is up and running (besides the cassette that I am fixing).
 


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