Hi,

I have two 8591As to check, and for both, I'd like to correct the timebase.

I followed the procedure in the service manual; it worked, and I correctly executed the CAL STORE command when everything was correct.

This manual matched the firmware version and serial number for both 8591As.

If I perform a PRESET or power cycle, the value contained in this TIMEBASE-related register reverts to the value before I tried to make a change.

?

For one, it's a value of 255 because the battery was completely dead.

After changing the battery, I was able to successfully redo all the calibration constants; the only value not saved in volatile memory is the TIMEBASE adjustment.

For the other 8591A, there was already a value, it was 87. If I change this value and save the calibration, also after a PRESET or power cycle, the value returns to 87...where is the error in this procedure?

?

?

Yves