Crazy HP 27
Message #1 Posted by Vittorio on 17 Nov 2001, 8:26 a.m.
Hallo everybody,
I am looking for some technical information about HP 27. I have one which is literally crazy. She casually switch on or not, when she goes you might be able to add a couple of figueres (right result) and then it goes of or display casually lits.
I thought of a poor contact between keyboard and main logic card but, replaced all of the pins with modern new contacts, nothing has changed. I have mesured tension on two tantalum condensers (orange) I have assumed to be PSU out. + 2.5V e -2.5V. All of the diodes seem to be ok (incirquit test). Time was over after finished all of this and I had to quit with no substantial results.
Now, I think next to make a little reverse eng. and draw the schematic from the PCB to reason about the circuitry.
Before doing that I ask here if there is any people who know some about repairing of this item and if somewhere is the schematic...
Thankyou in advance
Vittorio
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