Hello community. This is my first post although I always lurk here looking for great info.
I have a DX7 MK1 (completely stock) that is locked in the “Change Battery” screen even after replacing the battery. None of the buttons will work to get it out of this mode.
(For comparison, I have removed the battery from a recently repaired and working DX7 and it does not lock in this mode when the battery is removed. Pressing “cartridge” or “internal” will release this battery mode and the synth can actually be used.)
I have gone down the rabbit hole of replacing the diode, cap, and the two transistors in the battery circuit, to no avail. I’ve also tested all resistor values in this circuit and have also made sure that the @ 3.2 volts from the new battery is getting to the ROMs and continuity on these traces is perfect.
Also, all voltages are correct coming off the power supply.
I feel that perhaps a processor someplace is bad. The board looks good. No damage anywhere and I’ve been extremely careful with my soldering (I’ve been repairing stuff since the late 80s). I’m not great with digital circuitry though.
I was wondering if anyone had any leads, advice, insight, on what my be the issue?