Korg Poly-61 – Changing the NiCd to a Litium Battery

The Korg Poly-61, DCO analog synthesizer

The Korg Poly-61 has the same type of battery as the Korg Polysix, the type that creates the infamous battery leak disasters. Here’s how to modify the Poly-61 for a standard litium coin-cell battery. The coin-cell can easily be changed by the owner, without soldering.

Background

The original batteries in Polysix and Poly-61 are rechargeable. The litium battery is not. If you would just insert a litium battery in the circuit, the battery would break, so you need to stop the current flow from the PSU to the battery.

Old Crow has info on battery modification and battery leak repair for the Polysix. I Adapted it for Poly-61.

Changes

Remove this

  • Old battery
  • Resistor R70 (replace with diode)
  • Capacitor C29

Add this

  • Diode, eg 1N4148 (Please watch the direction, see schematic)
  • Coin cell battery holder
The changes
PCB positions of R70 and C29