Inductor on HP 25C board

[Harald]

Thanks to everyone for their comments and advice!

So far I have cleaned the PCB (the rough way by immersing it into 25% vinegar, the picture was already after inital cleaning, looked much worse to start with). I have replaced the broken oscillator inductor, then the ACT and the cathode driver wich both were not working properly. I replaced the ROM, but I think that was not necessary (but it gave me a chance to clean the PCB under the ROM) and finaly desoldered the RAMs and found that if I swap them (I installed sockets) the registers stop working and program memory partly works. At first I do get the correct key codes, but when I step through the program all I get is key code 40 (rather than 13 00) with the broken memory chip or without one at all. I wonder what that means. Are both memories not working properly? Or is there something else wrong?

Maybe someone has a memory chip he or she no longer needs, maybe because Bernhards ACT was installed, and would consider parting with it (for a resonable financial compensation)?

I know I could get this calculator back to life by simply installing Bernhards ACT. I already did that with one of my dead calculators, but in this case i'd prefere to get it working with the original RAM chips. Just because I really like these ceramic ICs with their gold plated lids ;-)

Cheers,
Harald