Encoder only increasing when moving left or right


I have just built my second Shruthi control board and observe some strange behavior with the encoder:
it always moves forward (increasing patch number or cycling right), even if I turn it to the left.

Otherwise everything seems to work fine: display and sound behave like they should and I can change presets in both directions via MIDI. The push behavior of the encoder does also work.

I looked through the forum for similar discussions and found some places were encoders behave strangely. But I could not identify what could be the reason in my case. So that’s why I am asking here for advice.

Some more specific information:
I have ordered the board and the programmed chips from here, and the parts by Mouser. The encoder has the ID 652-PEC12R-4225F-S24 (Bourns Encoders), just as recommended in the BOM. Firmware is 1.02 and I also checked that it is not in XT mode. All other switches and nobs seem to perform well.

Does anyone have a hint what could be the reason? Or suggestions how I could test malfunction of the encoder?


Previous builds: one controller board and three filter boards (SMR4 mkII, ladder and Steiner Parker)

Check the soldering on the encoder?

Or maybe it’s a defective encoder? This part from Bourns is actually quite sensitive to heat and fragile, I had to have it replaced on an entire batch of MIDIpals.

Thanks for the quick response!

I have checked the soldering, but without success.

But if you say that these parts are sensitive, I’ll probably best replace it with a new one and see.

Can you recommend any other brand that is compatible?


Alps, Panasonic, Song Huey, Alpha, Taiwan Alpha, CTS, Soundwell,…

Check that the pinning is the same in the data sheet. Beyond that, these are industry standard things. Any 11mm encoder shares most physical attributes with another 11mm encoder. Ditto for 9mm, 12 mm, 14 and 16mm! Shaft length, type, bushing, housing height can vary.

Of course, things like built-in LEDs, switches and such plus different mounting styles will also complicate matters.

20mm shaft plus 5mm bushing, top adjust with switch, 24ppr, 24 detents: 858-EN12-HS22AF20

Okay, I have to be careful with the pinning then.

Thanks for the advices!