Sunking POP!

[gtr2]

The Sunking I built a little while ago has a "POP" when engaged and disengaged.  It is wired according to the "true bypass" wiring scheme.  The pedal works fine but it's a distraction when engaging the pedal when a delay is on.  Obviously the input is grounded when the pedal is bypassed but is there an area on the backside of the circuit that I should place a cap and pull down resistor.  I'm not quite sure where to do this since the volume pot is essentially a variable resistor to ground and it's the last thing in the circuit with the true bypass wiring...

Thanks for any assistance!

Josh

[madbean]

Josh,

What type of bypass wiring did you use in this case?

[gtr2]

The standardized wiring diagram and the build doc notes for true bypass.

[madbean]

Try temporarily disconnecting the wires to the LED and see if you still get the pop. That could be the source of the noise.

[bangerang101]

Yeah, also if you find that the problem is the led causing the pop, have a look at this article from R.G.... http://www.muzique.com/lab/led.htm

[gtr2]

Disconnected the LED.  No change.  I did find a shaky ground on the 3pdt and I touched it up.  Now it only does a pop when the pedal is engaged.  It's not as bad as before, but it is there.  Not really noticeable with the volume at unity gain but if you use it as a boost its more prominent.

[madbean]

Hmmm. Might have to increase the pulldown resistor to 2M2. It could be a bad switch, though. Only other thing I can think of ATM is maybe disconnect the ground wire from the sleeve on the output jack. That's a shot in the dark. Or, maybe having C3 in there is somehow causing a discharge that is causing the pop.

[Jimihendrix1987]

Hi there Man !!

I've got a POP too   ... but it only does a "it" when the pedal is going to be engaged. I have tried to disconnect de LED, and there was no POP Then... It's a LED Problem...

But I don't know why?? I have built 3 sunkings and this is the fourth, everyone has the same components... WTF is happening?

By the way... I have tried what RG Keen says in his article... Look at the pic (but i'm not sure if i have done it properly). 47uF + 560 ohm resistor + 4.7k led resistor



There are LM313 diodes too  

I need tech help.. I'm a fucking noob... This afternoon i'm going to use different IC because I don't know what to do... HELP !! I need Somebody HELP !! 

[gtr2]

hmm...  I don't quite know what to say because my "pop" is gone

I replaced the spca7660 with a different brand and it stopped.  I'm uncertain why, but I know mine was not an led problem.  When my LED was disconnected it still made the "pop"

Josh

[Jimihendrix1987]

Thanks Josh !

But... Look at what I have found out 

I have several errors on IC voltages: Multimeter reads around 7.90v on Pins 1,2,5,6,7 (from IC1) and Pins 1,2,3,5,6,7 (from IC2)

That could be the source of the pop... I don't know ! But the effect sounds awesome in spite of those voltage readings !! What could it be?

[gtr2]

Check that r29 and r30 are indeed 27k.  Those are creating a voltage divider for VB. Also for any solder bridges in that area of the board.

[bigmufffuzzwizz]

hmm...  I don't quite know what to say because my "pop" is gone

I replaced the spca7660 with a different brand and it stopped.  I'm uncertain why, but I know mine was not an led problem.  When my LED was disconnected it still made the "pop"

Josh

IIRC you used the 7660SPCA in the sunking without any problems previously correct? What did you change it to that fixed it?

[Jimihendrix1987]

I'm sure there's something soldered wrong. I'm going to check everything up !!

I have several errors on IC voltages: Multimeter reads around 7.90v on Pins 1,2,5,6,7 (from IC1) and Pins 1,2,3,5,6,7 (from IC2)

Thanks gtr2.

This is the first time I get this problem, and I'm always using the same IC brands and capacitors. There's something soldered wrong SURE !! But it sounds good. How can it be?

[gtr2]

IIRC you used the 7660SPCA in the sunking without any problems previously correct? What did you change it to that fixed it?

I just changed the 7660scpa with another 7660scpa I had...

[madbean]

My first guess would be mismatched values on the voltage dividers for Vb as someone mentioned. If one of those were 2k7 instead of 27k for example.

What are you getting at IC3?