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I have repaired an 34C. It has the 2 disease as posted before but it has also another problem. When I turn it off and on again in few seconds everything is ok. But if I wait more than 5 seconds then it loses the constant memory and displays "Pr error".

Does anybody know the reason?

Thanks

Jon

Hi, Jon;

taking your own reference, position # 1 must be always used by RAM. This 8-pin DIP tab set has a separate +Vcc supply, so the chip positioned there (RAM) is always fed for as long as you have charged batteries installed. I saw your post again and compared the codes you posted: there is a ROM chip in the first position. My HP34C looks like this:

34C  N  S   34C/B-2102 00034-69110  1LB902 1MA10014 1MA115    (1)

I guess the "unknown" 8-pin DIP chip is the RAM chip, as the other have codes taht are close to the ones I found in mine. Simply exchange chips #1 and #2 in your calculator and tell us what happened. No chance to dammage the chips: except for pin #8, all others are connected in paralell.

Success!

Luiz (Brazil)


Edited: 6 July 2003, 12:15 a.m.

its 4th of July. Put that HP-34C in a drawer and deal with it tomorrow. Today, get out one of Carly's Kinpo calculators, and stuff some firecrackers underneath it and light the fuses.

:o)

Quote:
Today, get out one of Carly's Kinpo calculators, and stuff some firecrackers underneath it and light the fuses.

8^)

Or, if you can manage it, use dynamite sticks instead of firecrackers for an even bigger bang.

-Ernie