Korg Poly800/EX800 Users

By “early” I assume you mean one that does not have the solder pads between IC18 and IC19 where they would eventually put the battery at the factory. I’m guessing that was somewhere around serial number 020000 when they added the pads and serial number 040000 when they actually starting installing a battery. I’ve always said it’s better to only touch what you need to touch when making repairs. Much less chance of something going wrong that way. C87 is a filter that probably doesn’t affect anything whether it is there or not. C88 is bigger, and has allowed me to change a battery without losing patches. This is only useful if you know the battery is low but not dead. D23 allows the memory chip to run off the internal 5 VDC supply while the synth is powered on, instead of running off the battery 100% of the time. D15 connects your new battery to the memory and prevents the 5VDC supply from trying to recharge your non-rechargable 3V battery.

The way I do it is just remove R1 and D1 over near where the 9VDC adapter plugs in. The new CR2032 battery is soldered to the holes where you removed D1, the zener diode. You should see that the left side of the diode is connected to one side of R1. This is where the positive wire from the battery goes. The other side of D1 (near R2) is the negative (or ground) side.

 

So, you can remove those other parts at your own risk. They are near the memory chip and I don’t recommend using a soldering iron over there unless you need to fix something over there. If D15 is removed, it will either need to have a jumper installed to replace it or connect the battery directly to there. If D23 is removed, the memory chip will be running off the battery even when the synth is powered up, which hardly seems like a good idea. The memory chip is going to use the most power when you are storing or recalling patches. The battery should really only be responsible for keeping the contents of the memory alive while the synth is turned off.

 

Don Backshall