Sample Select knob jumps about

[Pastor-of-Muppets]

I bought a secondhand microSampler after GASing for one since they first came out. It seems to work fine apart from the Sample Select knob. If I press the [KEYBOARD] button next to it and then slowly turn the [SAMPLE SELECT] knob from its start position, the display shows 01, 02, 03, 17, 09, 11, 13 and keeps jumping about like that, until I get to about 12 o'clock on the dial, and then beyond that the display just shows "--------".

Am I misunderstanding how that knob is supposed to work? Is it supposed to cycle through them in order, or is that "random" order being shown due to having those samples assigned to keys in that order or something?

If it's not supposed to do that, any idea what's wrong and if it can be easily fixed? Is a bit of WD40 likely to help or make it worse? Should I crack the thing open and check the solder joints?

[voip]

It is likely that contact oxidation inside the rotary control is the issue. Rotating the selector knob a few times in either direction, before powering up the sampler, should at least provide a temporary solution. If this improves matters then at least this confirms that this is indeed the problem.

Some encoder types can be disassembled whilst still attached to the circuit board, and the contacts cleaned, taking care not to damage the delicate contacts.

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[Pastor-of-Muppets]

Thanks for the reply. Rotating it before powering up seems to make no difference

[SeedyLee]

Don’t use wd40! If you must, at least use a specialised electrical contact cleaner, but be aware that all such cleaners can displace any lubrication or grease in the mechanism. For an encoder, disassembly is recommended.

It’s probably easier to simply buy a new encoder, if they’re still an available OEM part.