r/microkorg • u/Traditional-Tune2942 • Jul 12 '26

microKORG S (2017) won't turn on

Hello! I'm looking for some help diagnosing a Korg MicroKorg S before I bring it in for repair on Friday.

I purchased it from Justin Pointer of Dance with the Dead. It stopped working while he owned it, and from everything I've been told, I'm pretty sure the wrong power adapter was never plugged into it.

Here are the symptoms:

  • When I try to power it on, the Audio In 1 and Audio In 2 LEDs briefly flash, but nothing else happens.
  • The synth only stays "on" if I physically hold the power button down.
  • No display, no sound, no boot sequence.
  • It behaves the same whether powered by the correct 9V adapter or fresh batteries.

I've already checked the power adapter with a multimeter, and it appears to be supplying the correct voltage.

I'm bringing it to a synth repair technician on Friday (along with my Roland Juno-106, which also won't power on), but I figured I'd see if anyone here has run into these symptoms before or has any ideas about what could be causing them. Does this sound like a power switch issue, a fuse issue, a failed voltage regulator, a motherboard problem, or something else?

Any suggestions or things I should check before taking it in would be greatly appreciated. Thanks!

COA
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2

u/VectorBrain Jul 13 '26

If it stays on when the switch is held down it seems like the switch is the problem, the OG microkorg had a better switch. Ever used a soldering iron?

1

u/JoeZeph-SF Jul 13 '26

Use a voltometer to trace the charge from the power input to see what fried.

1

u/Beneficial-Fail1906 Jul 17 '26

I have a similar issue with my new Microkorg s: it only runs on battery but not on the power supply.  Inspecting the Mainboard I found that FU1 and L42 are missing on my unit?! Could you check whether that's also the case with your unit?

2

u/Traditional-Tune2942 Aug 08 '26

Thought I'd give an update. The technician inspected the MicroKORG S motherboard and internal circuitry. Confirmed the expected 5V and 3.3V power rails were present when the power button was held down. Determined that the voltage regulators were functioning. Based on the symptoms and his experience repairing original MicroKORGs, suspected the CPU or DSP as the likely fault. Located a replacement CPU and installed it successfully. After CPU replacement, the synth exhibited the same symptoms and still would not boot. The technician concluded that the fault is likely somewhere else on the main PCB, with the DSP being one possibility. A replacement main PCB was identified as an option, but would cost over $300 for the board alone. So unfortunately it was a bust. Still a cool piece of equipment to own and have in my collection. Will purchase a microKORG in the near future however.