Re: HP 34c needs help Message #2 Posted by Tony Duell on 11 Oct 2005, 7:01 a.m., in response to message #1 by David Derrer
In the -C spice series, the memory (8 pin) chip closest to the display gets a separate power connection from the other chips -- it gets power all the time to maintain the continuous memory.
I _think_ the power pin is pin 8, I can check this on the schematic.
With the machine switched off (but a battery pack fitted), you should measure a little less than the battery voltage between the power pin of that chip and ground (-ve side of the battery). With the machine on, you should see the same voltage there (or a _little_ less) than on the power pins of the other memory chips.
If either/both of those voltages is incorrect, you have a problem on the flexiprint, or on the power converter PCB (open-circuit diode?). If they're both OK, I would, alas, suspect that memory chip.
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