Vintage Synth Repair

Hi group,

I've got a TX-816 on my workbench. On startup, 4 units shows a code 4 (low battery). On two units, the battery have already been replaced and shows 3.16 V (pretty badly solded, though. I desolded them and put a battery holder; cleaner and easier to service).

The voltage is correctly driver up to the RAM.

However, on startup, the code 4 is still displayed, and the battery voltage (Utility -> Battery) is still 0 V.

Do I have to reset something to clear the error? I've seen on the user manual there is a kind of error acknowledgement through MIDI dump...

Thanks,
François