HP Forum Archive 21

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HP-65 logic board repair - help required Message #1 Posted by Alberto Fenini on 16 Feb 2013, 8:31 a.m. ciao a tutti, last summer I have tried to repair an HP65 board, the project is still open, I have got stuck in searching for replacements parts for the PSU, but I'll work on it again in the near future. Now, I'm dealing with another one : The board looks clean, even if I think that the circled diode has been replaced in the past. This is how the display looks like : The first thing I have done has been to measure the three values Vss = 6.38 V Vgg = -12.40 V Vcc : 7.91 which look good to me, very close to those of a working HP65 I have. So the question is, what could be wrong ? The Hybrid ? What can I measure any further to troubleshoot the board ? Thanks again for help, Alberto

Re: HP-65 logic board repair - help required Message #2 Posted by John Robinson on 17 Feb 2013, 6:39 p.m., in response to message #1 by Alberto Fenini Alberto, check your clock signals next, PHI1, PHI2 and SYNC. Refer the document I sent you, if you can't find it, email me and I'll send it again. Cheers, John Robinson

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