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problem with knobs.


dtx

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Hello,

i've just finished my midibox today, and tried it.

i'm just using one aim and the core with 20 knobs and have a problem, i can resolve.

i've got a knob, wich give full of values without sense when i touch it, and some other wich give them right value, but send value in the channel of the first sick knob.

i verrified the soldering on the ain, everything seemed to be correct, also on the knobs, is it possible that a wrong connection between a knob and the +5v or mass causes this kind of problem ?

the non-used pin of j3 and j4 are connected to masse.

i also check the voltage to all the pin of the knob, and it was correct, unfortunately i don't know how use a ohmmetter !

have you an idea to where i've got to search the problem?

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dtx,

Sorry no definitive answer here, but I did go through similar trouble with an eight knob MB64 I did a while back. It does sound like messy supply or ground lines. It seems when I was searching or asking about mine, there may have been mention of a value of bypass cap or something which could be added individually (per pot or something). I went through hell on mine, and did much unnecessary pot swapping and rewiring. This was a homemade "all on one board" PCB, which had already been through too much, and much of the noise was knocked out by rerouting new lines with jumper wire IIRC. You might try taking three clean new wires directly to an external pot from the AIN or whatever, and see if it still does it.

FWIW- I think I may still even have one pot on there that jitters badly at one of the extreme ends of it's travel, but the box is just for testing, so it isn't hard to avoid.

Hopefully someone else here can point you to some filtering or noise tracking & reduction if that sounds like the problem.

Good Luck,

George

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Hiya,

Im no expert, but from my own similar problem with encoders (different, but similar problems) I suggest that you test each wire going to the pots to ensure connection to the ain board using the multimeter to beep the connection (if you know what I mean, testing for dud wires). Also try if you can to move the faulty knob to another shift register on the board if you have any left (make sure to change the reference in the asm code to reflect this). If all else fails swap the knob out, and the wire and the IC it connects to (if you know everything else works ok).

Uploading the midiio128 application also helped me pinpoint what was happening, this may not help you tho. This will show you the value being sent by the knob, if it is not like all the other knobs in its response then you know something is wrong for sure.

In my case I didnt actually solve the problem, but I got rid of it by moving the faulty knob to another shift register on the board.

It might not help, but best of luck!!

John

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