Excessive popping!!!!

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bassist001
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Post by bassist001 »

i just built an OCD pedal and for the life of me can not get rid of the stupid pop when switching on and off! ive tried putting bleeders on the last caps and nothing changed. took the led circuit out and nothing changed. the pop is controllable by the volume knob. so when the pedal is tuned down theres no pop and i found that if i ground it out at the last cap the signal goes away and no pop. but, cant get rid of it at all!! any thought?

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DrNomis
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Post by DrNomis »

bassist001 wrote:i just built an OCD pedal and for the life of me can not get rid of the stupid pop when switching on and off! ive tried putting bleeders on the last caps and nothing changed. took the led circuit out and nothing changed. the pop is controllable by the volume knob. so when the pedal is tuned down theres no pop and i found that if i ground it out at the last cap the signal goes away and no pop. but, cant get rid of it at all!! any thought?

Have you tried soldering a 2M2 resistor from the input on the circuit bord, to circuit ground?, the popping noise you hear is due to an electrical charge build-up in a capacitor on the input of the OCD circuit, soldering a 2M2 resistor from the input to circuit ground gives the electrical charge a path to ground so it can bleed away.... :thumbsup
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bassist001
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Post by bassist001 »

ya, that the bleeders i talked about ;) but ive got a 1M on the input and everything i tried on the output didnt work unless just grounded the signal out. and my switch grounds the input out when its switched into bypass. so im totally going crazy trying to find it haha

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Post by DrNomis »

bassist001 wrote:ya, that the bleeders i talked about ;) but ive got a 1M on the input and everything i tried on the output didnt work unless just grounded the signal out. and my switch grounds the input out when its switched into bypass. so im totally going crazy trying to find it haha

Hmmmmm....strange, 'cause adding the bleeder resistors usually cures the popping, I may have to have a good think about this..... :hmmm:
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Post by bassist001 »

ya! my same thoughts! its weird! haha thanks! i really appreciate it :)

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Post by Duckman »

AMZ. There's a nice article about different ways to rid that annoying noise.

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bassist001
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Post by bassist001 »

im wondering maybe if i fried my tant cap a little so now its passing DC. Are they known to be sensitive? Cause i measured about 4v DC on the negative side of the tant and there shouldnt be any DC signal that close to the output. Does this sound like a good place to swap a new part in? Im thinking that might be my problem, cause i also noticed a good amount of scratchiness on my volume pot. and that being after the tant with only a few resistors in the way would makes sense.

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Post by DrNomis »

bassist001 wrote:im wondering maybe if i fried my tant cap a little so now its passing DC. Are they known to be sensitive? Cause i measured about 4v DC on the negative side of the tant and there shouldnt be any DC signal that close to the output. Does this sound like a good place to swap a new part in? Im thinking that might be my problem, cause i also noticed a good amount of scratchiness on my volume pot. and that being after the tant with only a few resistors in the way would makes sense.

Image

Yes, they can be sensitive, I've had some Tantalum caps fail on me simply by being soldered into place on a PCB, so it's not uncomon, in some cases they can actually go incendiary, that is, they can spontaneously burst into flame especially if they become leaky, so, you could try desoldering the Tantalum cap, and replace it with a standard electrolytic cap of same value and voltage rating.... :hmmm:
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bassist001
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Post by bassist001 »

well i fixed it! the tant was still good but when i was testing around that area i noticed one of my resistors (R13) wasn't connected to the tant. i accidentally cut the strip on the board in the wrong spot. so it was bleeding the DC from the transistor into my output! gosh stupid mistake but hey i learned my lesson :D thanks again for all your help!! :)

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DrNomis
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Post by DrNomis »

bassist001 wrote:well i fixed it! the tant was still good but when i was testing around that area i noticed one of my resistors (R13) wasn't connected to the tant. i accidentally cut the strip on the board in the wrong spot. so it was bleeding the DC from the transistor into my output! gosh stupid mistake but hey i learned my lesson :D thanks again for all your help!! :)

No worries at all mate, glad you got it sorted in the end.... :thumbsup
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.

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