Drive Pedals have DC Leak & Switch Pop

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briancfb

New member
Hey all,

I have semi-successfully built the following 3 drive pedals: Super 64 (pre-taqueria supro pedal), Mach 1, and Chopshop V2. Two of these three pedals are experiencing DC leak on the output, and I believe this is the cause of the switch pop. All of the pedals work perfectly otherwise.

I am an absolute beginner to pedal building and would like some help on fixing switch pop on the Mach 1 and Chopshop. I am using breakout boards on all my switches. I believe I've narrowed my pop issues down to DC leak on the output jack. I'm reading above .5mv when the pedal is engaged.

I've done the following troubleshooting:

- Removed LED from circuits (not source of pop)
- Ensured pulldown resistors are in both schematics (links below incase I'm wrong)
- Ensured pulldown resistor values are correct
- Have swapped out switches at least once
- Ensured I have no cold solders, or shorts
- Tried the 10k resistor trick to no avail (10K Resistor on switch Output to Ground)


I've read up on many sources explaining switch pop. This has been my main source:
MrBlack - What Really causes Switch Pop

Here are the schematics for both pedals:
Chopshop v2
Mach1 Overdrive


Since I have DC leak, would I be looking to swap out the output caps?

Again, I'm a complete beginner, so I might need some help if I'm wrong about how I'm reading the schematics: I am making the assumption that the output caps are the last caps on the schematic. I am also assuming the pulldown resistors are the ones that are above 1M Ohms in the schematic- located closest to the input and outputs.

I have also heard the source of dc leak could be the electrolytic caps. I'm running cheap caps from bulk variety kits. The electrolytic Caps I used are all 25v rated.

Anyway, I'm confused on where to go from here. I don't have the proper equipment to test for leaky caps- so any help anyone can provide would be greatly appreciated. Additionally, If I'm wrong about the DC leak causing my switch pop, let me know what else I can test.
 
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briancfb said:
Hey all,

I have semi-successfully built the following 3 drive pedals: Super 64 (pre-taqueria supro pedal), Mach 1, and Chopshop V2. Two of these three pedals are experiencing DC leak on the output, and I believe this is the cause of the switch pop. All of the pedals work perfectly otherwise.

I am an absolute beginner to pedal building and would like some help on fixing switch pop on the Mach 1 and Chopshop. I am using breakout boards on all my switches. I believe I've narrowed my pop issues down to DC leak on the output jack. I'm reading above .5mv when the pedal is engaged.

I've done the following troubleshooting:

- Removed LED from circuits (not source of pop)
- Ensured pulldown resistors are in both schematics (links below incase I'm wrong)
- Ensured pulldown resistor values are correct
- Have swapped out switches at least once
- Ensured I have no cold solders, or shorts
- Tried the 10k resistor trick to no avail (10K Resistor on switch Output to Ground)


I've read up on many sources explaining switch pop. This has been my main source:
MrBlack - What Really causes Switch Pop

Here are the schematics for both pedals:
Chopshop v2
Mach1 Overdrive


Since I have DC leak, would I be looking to swap out the output caps?

Again, I'm a complete beginner, so I might need some help if I'm wrong about how I'm reading the schematics: I am making the assumption that the output caps are the last caps on the schematic. I am also assuming the pulldown resistors are the ones that are above 1M Ohms in the schematic- located closest to the input and outputs.

I have also heard the source of dc leak could be the electrolytic caps. I'm running cheap caps from bulk variety kits. The electrolytic Caps I used are all 25v rated.

Anyway, I'm confused on where to go from here. I don't have the proper equipment to test for leaky caps- so any help anyone can provide would be greatly appreciated. Additionally, If I'm wrong about the DC leak causing my switch pop, let me know what else I can test.
Click to expand...
Are the polarities on your electros oriented correctly? Also, can you post some clear well lit closeups?
 
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Yes the pulldown resistors are the ones just after the inputs. If the vol control is the last thing in the circuit before the output, it acts as a pulldown resistor as well.

You have DC leaking into the audio signal somewhere. It's more likely to be an issue with the wiring than bad parts. Make sure the ends of your wires as they come thru the solder pads are trimmed short - even one little strand can cause issue. And make sure you blow out the solder remnants afterwards. In general you want your soldering to be as neat as possible so spend some time and clean up the wiring.
 
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