Inductor on HP 25C board

[PANAMATIK]

(09-21-2015 03:48 PM)Harald Wrote:  The ACT and anode driver needed replacing. But now I get the screen filled with zeros every time I press Enter or a function key.
Am I right in assuming this means that RAM is not working? Shame, would have been nice to get this 25C back to life. Now it appears to be a candidate for Bernhards new ACT.

Edit: The issue has somewhat changed. I now have a non-programmable 25C. I have checked a couple of functions and they work, but whatever I enter in program mode, all I get is "13 00".
Is program memory located in one of the chips and the other one is for all the rest?

Program memory is located together with LastX Register in one RAM chip, the 8 registers 0-7 are located in the other RAM chip. If you get always 0.00 by recalling a register and GTO 00 in PRGM mode then the respective RAM chip is defective. Theoretically there could also the DATA line of the ACT defective, which reads and writes the RAM data.

The stack registers are not located in RAM chips, they are ACT registers. All calculations are valid. Thus you have a non-programmable HP-25 without registers, perhaps an HP-21 minus one -> HP-20

Bernhard