pedal only working when pot full CW

[tubbyblofish]

Hi, new to the art of pedal crafting. I am having trouble with my first build. Have put together the Earth Sounds Graphic Fuzz following two different schematics, resulting in two different boards

http://guitar-fx-layouts.42897.x6.nabble.com/earth-sound-research-graphic-fuzz-vero-layout-td19882.html

and

http://tagboardeffects.blogspot.com/2020/07/earth-sound-research-graphic-fuzz.html



I get a fuzz sound through but only when the filter B1M pot is full CW. And nothing like that shown in the description. Was wondering if anyone had an idea about debugging this?

[induction]

Post photos of the front and back of your board.

[tubbyblofish]

This is from tabbycat's upload




please excuse any none essential soldering is my first build

[tubbyblofish]

and this is using Zach's design





Also, I'm not sure I've used the correct terminology in 'CW' it is when the filter is turned up to maximum
apologies if that caused any confusion.

[induction]

I don't see any obvious errors, but I can't see the resistor colors or the precise placement of most of the components. Lug 3 of the filter pot feeds the output cap, so if the circuit is totally dead, you still might get output at when the filter pot is fully CW, but it wouldn't be fuzzy.

Can you take DC voltage readings on the pins of the IC?

Did you use an L741 or did you swap it out?

[tubbyblofish]

double-checked resistors and placement.

trialing again the output isn't fuzzy like I first thought

taken dc voltage readings as, (think I've done it correctly)

1 - 0                 8 - 0
2 -  0.19           7 - 8.98
3 -  4.43           6 - 0.22
4 -  0                5 - 0

used a UA741CP as read others had had success with it.

[induction]

The voltage on pins 2 and 6 is bad. It should be pretty close to what you get on pin 3.

Which build is this?

My suspicion is that the problem relates to the 2M resistor, but the photos aren't clear enough for me to see  very much. Whichever build this is, if you post hi-resolution photos of both sides, from a few different angles, I may be able to spot something.

In the meantime, measure the resistance across that 2M resistor. Also try re-melting the solder on both legs of that resistor.

Edit: I just noticed that your build from Zach's layout has both 1u caps reversed. Throw them away (I wouldn't re-use them for this build or anything else) and replace them with fresh ones in the right orientation and report back.

[tubbyblofish]

Voltages were for tabbycat's build

will do and hopefully get back to you soon.