guitar effect push pot replacement

[walterskalter]

Hi guys,

Being a musician relying on electronic gear a lot of the time, I'm learning myself how to do basic repairs of amplifiers, electric guitar circuitry and sound effect pedals. Recently, the save preset function on one of my effects pedals (an Electro Harmonix POG 2) stopped working.

Presets on the pedal are saved by pushing the potentiometer in the upper right corner for 2+ seconds. Turning that same potentiometer enables users to cycle through the various presets. The turning function still works, the push function doesn't. I noticed the pot is slightly bent, it probably received a blow during transport. I'm looking to replace it, but I can't seem to find the exact type of pot, nor the wiring diagram for the POG2.

I've found these very similar pots online (https://www.musikding.de/Potentiometer-9mm-vertical-print), but they don't have the "push" function. If anyone here would know the name of the potentiometer I'm looking for or where I could find it, that'd be a huge help.

Here's some photos that might help:

https://imgur.com/a/NtQ6KUK

Thanks in advance,

Walter

 

[wkrug]

I guess that is no poti - It looks like a rotary encoder from the manufactor ALPS.
When You can rotate it without endpositions it is surely a rotary encoder.
Every bigger electronic trader should have thoose things in program.
e.g. Mouser, Reichelt, Schuricht, and so on.
I depends where You come from.

Look at this:
http://www.audiophonics.fr/en/rotar...s-push-button-notched-shaft-15mm-p-13023.html
Or this:
http://www.audiophonics.fr/en/rotar...s-push-button-notched-shaft-20mm-p-13025.html

 

[rjenkinsgb]

It looks like a rotary encoder from the manufactor ALPS.

WKRUG is spot on, it's an ALPS miniature encoder or "digipot".
The legend on the PCB appears to be ENC1.

Have a look through the Alps list here to find the appropriate part number with the same characteristics - size, mounting style, number of detents per revolution, with switch, shaft length & style etc. then search for that part number on google to find a supplier.

https://www.alps.com/prod/info/E/HTML/Encoder/Incremental/EC11/EC11_list.html

If it's not an 11mm square one, start here instead:
https://www.alps.com/prod/info/E/HTML/Encoder/Incremental/Incremental_list1.html

 

[walterskalter]

Thanks so much wkrug and rjenkinsgb for showing me in the right direction.

The size is 11 mm indeed, but what bugs me is the number of detents per revolution. I count 20 increments per revolution on my encoder, but the ALPS website seems to offer only 18, 30 or 36 detents.

As the pedal only has 8 presets to cycle through, could I use an encoder with 18 detents? And does the number of pulses matter?

And now that I look at the circuit, I see the markings D4 to D15 right next to the various LED's. It's a very long stretch, but would it have anything to do with these "Detents"? See picture:

https://imgur.com/a/eMUftBj

I just hope the encoder isn't discontinued, the effects pedal being from 2008. Guess that'll teach me to stay with analogue effects ;-)

 

[Nigel Goodwin]

The size is 11 mm indeed, but what bugs me is the number of detents per revolution. I count 20 increments per revolution on my encoder, but the ALPS website seems to offer only 18, 30 or 36 detents.

As the pedal only has 8 presets to cycle through, could I use an encoder with 18 detents? And does the number of pulses matter?

It doesn't matter, the only difference is that it will need to turn further, or turn less, to get the same effect.

 

[walterskalter]

It doesn't matter, the only difference is that it will need to turn further, or turn less, to get the same effect.

Okay, so if I install one with 18 detents and 9 pulses, I would need to turn twice to cycle one step, that's it?

 

[Nigel Goodwin]

Okay, so if I install one with 18 detents and 9 pulses, I would need to turn twice to cycle one step, that's it?

It should step every click, just as the old one does, it's simply that there's less clicks per revolution.