Restore a Pioneer keyboard (27s)

[franz.b]

(05-23-2022 01:58 AM)GreyUser Wrote:  MACHINE RESET should not appear in normal operation, it indicates the processor was reset and register contents lost but the contents of the external ram survived. It is normal on a 42S that has been converted to ferromagnetic ram when the batteries have gone flat or removed. Replacing batteries on an fram 42S will always result in the reset message because the fram contents always survive a power loss.

The OP’s problem sounds like a leaky keyboard matrix. Any cross point in the matrix that has a resistance of even a few megohms will cause processor lockups. Pioneer and 48 keyboards (which are electrically identical) must be absolutely clean and contaminant free when reassembled. Anything conductive whatsoever will cause processor lockups that clear temporarily with a hard reset which is most easily accomplished by removing batteries and shorting the terminals together with a coin.

If the leakage is present in a single key crosspoint, most Pioneers will display the offending key name at power up. Multiple leakage paths will usually result in a blank screen. Monitoring supply current at turn on is the easiest way to diagnose. I’ve got those values documented around here somewhere if anyone needs them. Post if interested.

Thanks, but the calculator works normally when used continuously, the problem you mention should give symptoms continuously, not just after weeks of inactivity. Is it right?
In any case, if you also want to post the values of the ignition current, I think they can be useful to those who repair these machines.