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Projects => Tech Help - Projects Page => Topic started by: insomniac2295 on May 19, 2012, 09:16:51 PM

Title: Serendipity Voice knob trouble
Post by: insomniac2295 on May 19, 2012, 09:16:51 PM
Directing this thread over to the Tech help forum now that I know what the voice knob actually does and that mine does not work. I've swapped out the pot, both tested pots function on their own, but don't appear to do anything in the circuit. The rest of the pedal is fine, I just don't get anything out of the voice knob. Could someone clue me in as to what might be causing the problem?
Title: Re: Serendipity Voice knob trouble
Post by: jkokura on May 19, 2012, 09:48:20 PM
If either R3 or C3 were an incorrect value or not properly soldered into place, that would be an instant and obvious issue. Other than that, We'd need some pictures and/or voltages to tell you. Mostly of the IC itself.

Jacob
Title: Re: Serendipity Voice knob trouble
Post by: insomniac2295 on May 19, 2012, 10:08:42 PM
My meter is busted so, I'm going to try to do this manually. Just audio probed it and it seems the signal stops after C3. I shall replace C3?
Title: Re: Serendipity Voice knob trouble
Post by: insomniac2295 on May 19, 2012, 10:28:36 PM
nevermind... screw it. i'm headed out to buy a new multimeter. i'll report back when i get some voltages
Title: Re: Serendipity Voice knob trouble
Post by: jkokura on May 19, 2012, 10:49:56 PM
After C3? No, there should be no sound there. That's VB.

Jacob
Title: Re: Serendipity Voice knob trouble
Post by: insomniac2295 on May 19, 2012, 11:34:41 PM
Yeah, I realized that after my post  ::)
Anyways
*DC voltage at power supply: 9.47
*DC voltage at board in: 9.47

IC1 TL062-
1: 4.73
2: 4.74
3: 3.21
4: 0
5: 4.55
6: 4.74
7: 4.74
8: 9.47

Q1 2n7000-
S: 4.42
G: 4.73
D: 4.73

Q2 2n7000-
S: 4.58
G: 4.73
D: 4.73

All voltages checked and double checked.
Title: Re: Serendipity Voice knob trouble
Post by: jkokura on May 20, 2012, 01:08:28 AM
hmm...

Nothing looks wrong with your voltages. And you've triple checked the value of your pots?

Jacob
Title: Re: Serendipity Voice knob trouble
Post by: insomniac2295 on May 20, 2012, 04:20:05 AM
(http://i832.photobucket.com/albums/zz247/blakepekkala/60311a04.jpg)
(http://i832.photobucket.com/albums/zz247/blakepekkala/b691887a.jpg)
Title: Re: Serendipity Voice knob trouble
Post by: jkokura on May 20, 2012, 04:26:46 AM
And you've triple checked the value of your pots?

Jacob
Title: Re: Serendipity Voice knob trouble
Post by: mgwhit on May 20, 2012, 12:26:53 PM
Looks like you may have swapped a 3M3 for R1 and 100Ks for R6 & R7, but those shouldn't cause any problems.  (Apologies if I'm misreading the multiplier band on those -- looks orange to me.)

R3 and C3 look good.  Couldn't read R9 because it's standing, but that shouldn't really affect the Voice knob function.

If you can put up a better, less angled, photo of the board, I'd be happy to go over that.  Backlit would be even better.  Can't tell if there's a bridge to ground on your voice pot connection points or if that's a shadow.
Title: Re: Serendipity Voice knob trouble
Post by: frankie5fingers on May 20, 2012, 10:16:41 PM
+1 on the bridge at the voice pot.
Title: Re: Serendipity Voice knob trouble
Post by: insomniac2295 on May 21, 2012, 02:21:21 AM
Solder bridge! That fixed it!!! I can't thank you all enough!!!  ;D ;D ;D ;D ;D ;D ;D ;D
Title: Re: Serendipity Voice knob trouble
Post by: irmcdermott on May 21, 2012, 02:26:31 AM
Quote from: insomniac2295 on May 21, 2012, 02:21:21 AM
Solder bridge! That fixed it!!! I can't thank you all enough!!!  ;D ;D ;D ;D ;D ;D ;D ;D

Glad you got it working!
Title: Re: Serendipity Voice knob trouble
Post by: insomniac2295 on May 21, 2012, 03:02:54 AM
Another example of why it's always a good idea to get a second set of eyes.
Title: Re: Serendipity Voice knob trouble
Post by: mgwhit on May 21, 2012, 03:11:26 AM
Very cool -- have fun with it!