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+--- Thread: HP-65 logic board repair - help required (/thread-239160.html)
HP-65 logic board repair - help required - Alberto Fenini - 02-16-2013
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 - John Robinson - 02-17-2013
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