3 Apr
2014
3 Apr
'14
8:15 a.m.
-----Oorspronkelijk bericht-----
Van: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org]
Namens supervinx
Verzonden: donderdag 3 april 2014 9:42
Aan: cctalk at classiccmp.org
Onderwerp: HP 9810
Hi!
I'm servicing a 9810.
The 1A slow-blow fuse is gone.
Before I replace it and try to power-up the machine, anyone is familiar with this
calculator? What should I check?
Thanks!
Remove the cpu and memory boards, place a dummy load in the 5V line (21W bulb or something
like that)
And check all the voltages, if needed repair the PSU, than replace the cards and check for
function.
You can find the schematics on the HP computer museum site
http://www.hpmuseum.net/exhibit.php?hwdoc=51
And if you are a member of the HPCC you can read Tony's excellent repair manual which
was published in the DATAFILE journals of the HPCC.
Be careful the HP 9810 uses 7400 and 74H ttl both are sensitive for supply spikes, so
check the power lines also with a scope noise and spike levels.
The PSU is protected by the line fuse but there's also a overvoltage protection on the
power lines, formed by 3 or 4 crowbar circuits which shortens the power line when a
voltage is above threshold.
A small warning, Memory and ROM's are somewhat sensible for wrong voltages, so be
careful!
-Rik