I also removed and reinserted all the socketed chips I've put tape over where the trace is cut and used my multimeter to check that the trace was cut correctly - no voltage going to C106.
#Korg poly 800 battery mod
Here's two images showing the mod I've done (please jump in if you spot anything dumb I might have done).
![korg poly 800 battery korg poly 800 battery](https://3.bp.blogspot.com/_FMBJEkaC8Lw/R1GHNEgDraI/AAAAAAAALz8/CNbtQxo8UHU/s1600-R/mount-top.jpg)
I looked for any possible stray piece of solder on the board and looked elsewhere within the synth for any possible broken connection. I've rechecked and redid all of the soldering and tested the traces at D15 and C106. When I power up the synth it shows the error message and I cannot get it to go into any tape load mode or produce any sound. Where should I begin troubleshooting this? If I remove the CR2032 battery the display goes blank and the synth appears to go dead until I re-insert a CR2032. When I power up the synth it goes straight to this error code and I cannot produce any sound or get the synth to go into tape load mode using the rear switches. The load procedure seemed to stall and now the display shows an error code in the image below. I then plugged in an MP3 player to reload the factory presets. When I completed adding the battery I powered up and synth behaved normally and was able to make a simple patch to test that the key contacts were working. While washing the old keys and preparing the key contacts for cleaning I decided to add a memory backup battery following the instructions at
![korg poly 800 battery korg poly 800 battery](https://www.synthfind.com/wp-content/uploads/2018/02/korgpoly800.jpg)
There are some non-working keys so I disconnected and dismantled the keybed. Patches were lost as soon as I powered off the synth as this early Poly 800 didn't come with an internal memory backup battery. wav file which all loaded and the synth played as expected. The synth powered up and I was able to reload factory patches from a. I bought an old Korg Poly 800 for a few euro knowing it might never work so I'm willing to use it to learn some basic repair skills.