Bootleg OD Crackle/Dropout

S

sean2damax

New member
Just finished wiring up a Bootleg OD and I’m getting crackle that sounds like a bad connection. I physically moved things and poked around but couldn’t find any loose components. Went through and reflowed anything that looked imperfect. Not sure where else to check next.

Im not sure if this is related, but the signal is also dropping out if I have the drive pot up, and it gets worse if I play harder. Comes back after a moment if I stop playing.

I swapped each one of the IC’s - no change.

Thanks for the help!
 
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Maybe a dodgy cap sounds like dc leaking but could be a few things

Check all your caps especially round the drive pot

Post some nice clear pictures both sides of the board so we can clearly see all components and trace your wiring to jacks, 3PDT etc
 
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music6000 said:
Can you give the Voltages at the Op Amps & TC1044S, Pins 1 through to 8 on each.
1 ---- 8
2 ---- 7
3 ---- 6
4 ---- 5
Click to expand...
TC1044S:
1 - 8.48v
2 - 4.33v
3 - 0v
4 - 139mV
5 - 353mV
6 - 3.9v
7 - 5.4v
8 - 8.5v

LM833:
1 - 14.1v
2 - 11.9v
3 - 11.7v
4 - 0v
5 - 13.5v
6 - 13.5v
7 - 13.5v
8 - 16v

NE5532P:
1 - 11.5v
2 - 11.5v
3 - 10.7v
4 - 0v
5 - 11.7v
6 - 11.7v
7 - 12v
8 - 16v
 
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Is your crackle constant or only when you turn a pot etc

I'm not sure you're getting the correct VREF voltage you should be getting 16 / 17v from your voltage doubler to your op amp pin 8's which you are, so looking at the power section VREF should be half of that, looks like you're getting 11.7v your 2 voltage divider resistors R100 and 101 are the same value so it should be half they're definitely both 47K

Using Chucks calculation here for working out what you should get out the TC1044

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So from your playing harder description it sounds like something may be mis biased

Check what voltage you get at the junction of R100 and 101, pin 5 of IC1.2 comes directly from VREF so I'd expect 11.7v at the junction

I'd also check their solder joints and C103

What's Q1 and 2 voltages

All your component values and orientation look correct can't see R13 thought
 
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R13 is Brown/Black/Black/Brown/Brown

Q1: 1) 5.8v 2) 5.3v 3) 16.1v
Q2: 1) 4.9v 2) 5.3v 3) 16.1v

Now i'm getting 5.5 and 6.7v on pins 2 and 3 of the 833, and 6.6, 6.3, 15.4v on 5,6,7 of NE5532. All other pins have stayed the same.

Getting 6.6v at the R100/101 junction at the moment.

Here's a video of what's happening. The crackle is intermittent. The dropout happens every time I play harder.
https://imgur.com/a/B95Gkea
 
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music6000 said:
You sure you haven't got a Dodgy Guitar Lead or Patch leads.
Do the Wiggle Test on all leads connected to pedal.
Plug into another Working pedal & make sure!
Click to expand...
Definitely good to go on leads outside the pedal. I’ve used two different 9v sources as well. Neither of the issues continue to happen when the pedal is in bypass either.
 
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The only thing left is the wiggle test on the op amps while Hitting the strings, then move to the Electrolytics, then the Capacitors.then transistors ....
Its obviously a Dry joint or failing component !
Have you ruled out the Footswitch, it looks like a Cheap unit.
Stomp on it a Dozen times and see if there is any change.
 
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The crackling at the beginning sounds like something in the power section

16.1v coming out of IC3 is about right with 8.5v from your adaptor give or take a wee bit of voltage drop

So on the cathode of D102 you should have 16.1 and at the top of R100 that looks correct , at the voltage divider junction you should have around half that 8v ish you have 6.6 could be your meter loading it down or a component pulling it down or it could be fine

At pin 5 IC1.2 you get 6.6 that tells us it's getting what VREF puts out so that's connected and VREF works for that part, your getting 16.1 at Q1 and 2 collector so we know that's good coming out of the power section,

I'd check C103 to make sure its not pulling anything to ground on the negative side and reflow solder connections in that area

Its basically a process of elimination as you know, the circuit obviously works aside from the crackle

I've no idea if dropping 1.9 volts, 16.1 instead of 18v and a tad low VREF would mis bias the circuit to the extent it would do what it does when you play hard

A faulty drive pot could cause that with no power to the circuit check the resistance between pins 1 and 3 changes as you rotate it fully CCW and CW one way full resistance the other a few ohms you may not get accurate readings you're just checking it changes it doesn't give infinite readings etc

Do you have an audio probe if I can't find a fault doing all the usual visual and voltage checks I go straight to mine
 
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Thank you to all that helped here, but I just tossed the board. Couldn’t absorb any more failures.

All 100u caps were swapped, drive and filter pots, and the 3pdt were swapped. No dice. Thinking now, it could have been a 5817 that was letting vRef or +18 come backward in the power section? I didn’t have the patience to find out for sure.

We’ll hope for better results on the rebuild haha.
 
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