Satori Synthesis

A good customer has brought along another Synthesizer for repair. This time it’s a Korg Microkorg.

The faults reported were the filter cut-off frequency potentiometer and some non operational keys

Video before the repair:

Frequency Pot:

The frequency pot was identified as knob 1. A 10K 4 pin pot. Yes a 4 pin pot. The 4th pin can be a center tap or as a dummy pin.

A quick check of the circuit diagram and measurement of the other pots showed it was a dummy pin and connected to GND.

The search for a replacement lead to possible genuine ones in LA and Australia. Both had massive shipping and import duties.

Other alternative versions were found from Germany and China. BUT upon arrival these are 4 pin pots BUT they both had much too short shaft lengths.

In the end the repair consistented of fitting a 3 pin long shaft 10K pot and using wires to make a suitable connection.

I read online that these Korg used poor quality pots and suspect at some point the others will need to be replaced. I will suggest replacement of all for good quality Metal shaft pots at some point.

Non Operational Keys:

So the keys on the Microkorg are conductive rubber membrane switches.

The PCB gold contacts are prone to corrosion especially at the edge where the gold meets the copper tracks. Upon checking continuity it was found that there were two breaks. Some fine resist scraping and plenty of solder flux the gaps was bridged with solder.

Image of the tracks

Also while removing and inserting the keyboard connection multiple times I found an number of the connector joints had become open circuit. You can clearly see a ring around the connect pins and the pads.

After repair and reassembly a good clean an a full test it was completed. The best bit about repair is having a good few hours of testing of a classic synthesizer.

Video of After Repair

Get in contact if you would like your Korg Microkorg repaired. Very competitive rates.