Brown Betty

LanePw

LanePw

New member
I'm having an issue with no sound when the effect is engaged. The indicator led works as should and I've got sound in bypass. Only L3 inside is lighting up dimly. I double checked the LED orientation on the rest and they're correct and worked on my breadboard after removing to check them.
I'm getting almost 6v on one side and 3v on the other of the one that's working and none on the others. All IC's are getting power. Kind of stumped on this.
 
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LanePw said:
Pot's still scratchy after cleaning. No sound with effect engaged still. Bypass works fine.
Click to expand...
I need to know every/ what components have been removed & replaced by you.
I was the 1st to build this circuit way back, no issues.

Brown Betty

This was on the old Forum & Lost. Plenty of adjustment to fine tune your Overdrive/Distortion needs. Mods : Battery Clip & Stereo Input Jack.
forum.pedalpcb.com
 
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music6000 said:
I need to know every/ what components have been removed & replaced by you.
I was the 1st to build this circuit way back, no issues.

Brown Betty

This was on the old Forum & Lost. Plenty of adjustment to fine tune your Overdrive/Distortion needs. Mods : Battery Clip & Stereo Input Jack.
forum.pedalpcb.com
Click to expand...
Replaced:
C6 (47pf, measured 44pf)
L1 & L2 with green 3mm Led (out of red)
Gain pot (A1M)
Volume pot (A50k)
Mid (C100k)
All 4 TL072 IC's
Shunt between C6/L2
Shunt between L1/L2
Shunts only because there was no continuity at those locations.
Volume pot due to scratchy that wouldn't clean up, and mid pot broke from bending back to check solder joints and continuity.
Gain pot only because everything left in that branch tested good after gaining continuity.
Had to strip and solder the switch lead from the switch PCB to main PCB due to wire breaking from manipulating it during testing.
Parts sourced from Tayda, and Mouser.
 
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History on my build. I spent between 6-7 hours on just the PCB. I measured and tested all components during the install. I used a magnifying lens while placing components to avoid accidentally placing them in the wrong place. I mark off each component as I place them. Connotation over a week and a half as I was a few resistor values short and wanted the exact values.
I've checked continuity on the switch in both positions. Done all checks you've suggested. Checked voltages on all pins of the IC's. Traced out and tested the entire power circuit.
I've got 4-5 other builds from PedalPCB with zero issues from the first power up. This one has me questioning my sanity, and if I should sell all of my parts stock and soldering station. If it's just a bad board, I'd feel silly then.
 
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The three electrolytics tested well before installation. I've checked them this morning and all showed resistance that changes in a counting down manner using continuity on the multimeter.
 
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I've just ordered another board. I've lost confidence in this particular one. I'll have to order a few more parts, but I was really set on hearing this. Again, thank you so much for going through this with me.
 
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Hey I think you'll get the second one right I'm sure. I look at it as you can always have this one as a side project to work on, and one day it'll work and then you have the twin sisters!
 
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What's your R19 value doesn't look correct should be 470K looks like 5K6?

IC3 pins 1,6,7 and IC4 voltages look off all your VDD reference points should be near what's coming out of pin 7 IC1 4.44v I'd check all your VDD points on the schematic see if it narrows down your problem area
 
Last edited:
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Here's a closer picture of the R19 section. I'll compare it to the rest of the 470k strip that I have when I'm off work this afternoon. I'll even throw a few on the tester, and multimeter to verify.
I'll plan on checking all of the VREF points also. I've got a few days to burn before the new one arrives.
 

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If it's not too late for me to jump in here...
IC1 voltages look good.
IC2 voltages look good.
IC3 voltages are outta whack. pin 1 too high, pins 6 & 7 too low.
IC4 voltages are outta whack, explains why the VOLUME control is scratchy.

Re IC3, my guess is R12 is broken, has a bad solder joint, or a broken pad. Another possibility is all that flux residue on the board has created a leakage path. We can't see most of the solder side due to the pots. Clean the board thoroughly with IPA.
 
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Chuck D. Bones said:
If it's not too late for me to jump in here...
IC1 voltages look good.
IC2 voltages look good.
IC3 voltages are outta whack. pin 1 too high, pins 6 & 7 too low.
IC4 voltages are outta whack, explains why the VOLUME control is scratchy.

Re IC3, my guess is R12 is broken, has a bad solder joint, or a broken pad. Another possibility is all that flux residue on the board has created a leakage path. We can't see most of the solder side due to the pots. Clean the board thoroughly with IPA.
Click to expand...
Not to late at all. I'm open to all advice. I'll check both sides of R12 too. Thank you.
If I'm bending the pots back to do more continuity checks I'll get more of the flux off while I'm at it. I tried IPA but it just looked like it was working with a brush, but when it evaporated it looked like it really just spread it around.
 
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You have to flood the board, scrub with a toothbrush and flood again. Make sure dirty IPA does not get into the pots. Clean IPA is ok. Once we get the IC3 pin 7 voltage corrected, the other voltages should come back into the correct range. Look for solder splashes and conductive debris on the solder side after you get it clean.
 
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