madbeanpedals::forum

Projects => General Questions => Topic started by: AJPennypacker on March 08, 2016, 03:39:54 AM

Title: This POP has me beat
Post by: AJPennypacker on March 08, 2016, 03:39:54 AM
Hi all, appreciate your help on this one, built a Jules Cavern from rullywow which is a great sounding little delay, the only drawback is that I'm getting a pretty big pop when first engaging the pedal. With a few clicks on and off it goes away but I'd like to eliminate it if possible. The board does have a pull down resistor so don't think that's the issue. I've read about leaking capacitors causing pop so I've even replaced all the electrolytics with no success.

Any help greatly appreciated.
Title: Re: This POP has me beat
Post by: pryde on March 08, 2016, 04:29:46 AM
Make sure the PDR is correct value. Also try raising it to 2M2. If no luck try another PDR on the output.

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Title: Re: This POP has me beat
Post by: pryde on March 08, 2016, 04:31:09 AM
Also reflow all solder joints on the switch.

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Title: Re: This POP has me beat
Post by: AJPennypacker on March 08, 2016, 01:06:30 PM
Hey thanks very much will give it a go today.
Title: Re: This POP has me beat
Post by: AJPennypacker on March 08, 2016, 06:23:09 PM
Unfortunately didn't resolve the issue, anyone with more experience chime in but my thinking is that since I get pop when first clicking on but then nothing if I play it for a bit and click off and on, it's likely to be a leaking cap..... When off/not being played it seems like the pop builds up.

If this make sense does anyone know a way to check for this type of issue. Don't really want to replace all the non-elec caps but I'm obsessing so that'll likely be my next step.

Thanks again for the suggestions pryde
Title: Re: This POP has me beat
Post by: tol on March 08, 2016, 06:57:01 PM
the only thing that worked for me was to use an optical bypass board AND add 2m2 resistor on the output. since there was an extra ground pad on the bypass pcb, I soldered the pdr directly to the bypass board.
Title: Re: This POP has me beat
Post by: kinski on March 08, 2016, 07:21:17 PM
Try a lower value for the output pull down. Like 100k-500k. That's worked for me on a few occasions.
Title: Re: This POP has me beat
Post by: rullywowr on March 08, 2016, 07:51:02 PM
I agree, you might want to try putting a 1M resistor on the cathode (-) of C4 and attach the other end to ground.  Using an optical bypass like the Detour PCB may help too.
Title: Re: This POP has me beat
Post by: AJPennypacker on March 10, 2016, 04:27:08 AM
Fixed! The resistor on C4 seems to have done the trick. Thanks very much for the advice.