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HP 85 power failure - Printable Version

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HP 85 power failure - Claudio Perottoni (Brazil) - 07-01-2010

Hi Folks!

I have a HP85 that just stopped to power on (no beep, no leds on, nothing on CRT). I have noticed that the power transformer (HP part number 00085-60017) has become very hot, as did the 2N6317 component on the PS/PTN board. Could anyone please provide me some details about the power transformer? For instance, what are the expected voltages on the connector J7 of the PS/PTN board (three conectors, red-white-red, that comes from the power transformer) for 220V input voltage? Before attempting anything I would like to check the output from the power transformer. Any other hint on the possible origin of this problem that could help to bring my HP85 back to life is very welcome!



Re: HP 85 power failure - Thomas Falk - 07-02-2010

Hi Claudio,

at the address


you can find an service manual for the hp85 under the name of a Computer Laerning Guide:


On Page B5 you will find some voltages to expect on the boards. I suspect that the transformator is not the cause of your problem.

I wish you luck,


Re: HP 85 power failure - Claudio Perottoni (Brazil) - 07-02-2010

Dear Thomas,

Thank you for your comments. I have taken a look at the HP85-Repair Course manual and there is now information regarding the output voltage of the power transformer. I agree that the transformer is probably ok, but I would like to start checking the board voltages from the very beginning. Following the instructions on the Repair Course manual, I have checked voltages on J1 and J2 board connectors on the HP 85 rear board and they are all dead. There is probably a short-circuit somewhere...