I recently did the battery backup mod on my Poly 800 MKI. I used a salvaged motherboard lithium battery thingy with a new 3v CR2016. Originally, I found that I had misinterpreted the instructions on
analog.no (the ground is the solder island to the "front" of the synth) and connected it backwards.
My backup was not working. I have disconnected (but left on and protected with electrical tape) R1 and D1 as described. Even after fixing my battery polarity, the synth will not save patches more than a few minutes.
Any sort of stuff I can check? Some of those trimpots that may be... off? I'd love to use this in a performance in the future, but won't if I have to bring a laptop/mp3 player just to reprogram it when I get there. I suppose that wouldn't be too bad...