Re: Not-so-dead DX7 Mark I - The saga continues...

No, zener diodes are a special type of diode, that's just made for a basic kind of voltage regulation.

Any small signal diode would do, for the 3V battery one, but since you're ordering one, it was originally a germanium diode - an OA95, according to the schematic, but any small germanium diode would work if you can't get one of those.

In the attached picture, you see it labelled as D4 - just above the middle, on the left.  The orientation is important - diodes have two different ends; an anode and a cathode.  They often have a stripe across the cathode end - which is shown pointing to the right, in the picture - pointing away from the positive terminal of the 3V battery.

An OA95 is a clear glass bead, with a red or dark coloured end, indicating the cathode - see attached example.

If you have a multimeter / test meter, you should be able to check continuity between the positive terminal of the 3V battery, and the clear end of your existing diode (the anode).

I don't have a picture of the physical location, but I would guess it's quite close to the battery.

- Andy