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HP32E Power Supply (Or equivelent Spice) Voltages
12-28-2021, 11:35 PM
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HP32E Power Supply (Or equivelent Spice) Voltages
Hello All,

I was given a non working HP32E for Christmas by a dear friend. He found it somewhere, with the battery all corroded, and figured it would be an easy fix. Knowing I am a EE, he figured the solder less design would be interesting to me (Which it is!).

So the battery was carefully removed and it became clear the ribbon cable on the battery end was eaten up, which based on searching the internet is pretty standard. What is not standard is that the battery (I will say chemistry to be safe) migrated into the power supply board. The flex that went onto the back plane was not damaged, however when trying to remove the flex to assess the damage (and it is great), a number of the tacks on the PCB lifted off (and all the pads are highly corroded, I have never seen a circuit board in such bad shape). I have done some reverse engineering and made a new flex by hand using copper tape, and tested it and that is ready to go. However, I do not have the voltages for the power supply.

When looking online I did find a schematic for the 32E, a couple actually, and they did not consistently provide a reference point. However, after some reverse work of my own, I know everything that I need except for the turns ratios for the transformer. I would like to construct a "novel" board that provides stable voltages to system. While I feel comfortable in moving forward (to a degree), I really do not want to blow out some amazing and irreplaceable chips and ruin a piece of history by guessing or getting "kinda close".

Therefore, if someone would be willing to measure all of the voltages from within their spice calculator, specifically on the flex/ribbon that goes onto the backplane, I would feel comfortable safely moving forward in working on the device and trying to bring some life into this amazing calculator.

Thank you in advance,
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HP32E Power Supply (Or equivelent Spice) Voltages - joey - 12-28-2021 11:35 PM

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