Here is a quick “freebie” of sorts. I’ve had this PCB for a while and used them now and then to fix dead 3v coin cell batteries on Yamaha DX7’s and other synth’s and drum machines. You can order the blank PCBs yourself or download the BRD file and get them made however you want.
The description is:
This item is a battery holder, coin cell and adapter PCB that lets you mount a standard CR2032 battery holder over top of a PCB layout that uses a soldered-in battery. It basically converts the pin layout from one of many odd 2-pin and 3-pin board styles into the common battery holder style. In the future, battery replacement will be a snap! Save your gear from leakage, damaged traces and lost sounds!
It will work with many synthesizers, drum machines or effects gear provided you have room inside the unit. The board can be mounted using wires, connector pins, component legs, connectors, etc. You can mount the board directly above where the old battery used to be or any convenient location as long as the board and battery are secure and absolutely insulated from any metal.