HP-67 1706A00901 [RA and RB with Spike, doesn't read - doesn't write]

[albertofenini]

Hi everyone,

this is a working HP-67 but the card reader is not reading
Based on the suggestions received in the thread "Testing the HP65 or HP67 card reader sense amplifier" we did some tests
In the following pictures you will see the following measures :
CA (blu wave) and RA (red wave)
CB (blu wave) and RB (red wave)
We noticed that when the calculator is doing nothing (display 0.00) both RA and RB have a spike
We used the SD-14A Moon Rocket Landing card as a test
Apparently RA and RB have a good waveform but nevertheless the HP67 shows a Error Message
The same card has been tested with a couple of working HP67 and it works

Any suggestion will be appreciated
Thanks for help and take care !!!

Pictures here : HP-67 1706A00901