Anxiety Disorder too distorted – Volume pot not working

[Ape Chimpenson]

Hey everyone,

I just finished the Anxiety Disorder Drive Pedal kit (v 3.0 – ordered at Musikding.de), but I am frustrated with it. The LED works, the bypass works and I also get sound, when switching it on. However the volume pot seems to be doing nothing. Even at 0% it is quite loud. Turning the pot up to about 80% doesn’t do anything (except for it scratching loudly). After 80% it gets even louder but from this point the sound by then is clipping and sounds awful. Also using the boost switch produces too much clipping / distortion – even when the Volume Pot is below 80%. The Tone Pot doesn’t seem to have a great effect, except for cutting harsh highs when turned all the way up. The Gain pot seems to work as inteded.

I already tried to resolder all the resistors I could reach without desoldering the pots. As this is my first attempt of building a pedal I don’t really know where to start and hope to get some insights from you experienced builders.

Tanks in advance

Ape

https://guitarpcb.com/wp-content/uploads/2018/06/Anxiety-Disorder-Build-Document.pdf

[Billy]

All your component values and orientation look correct

The germanium diode D1 I’m not sure some Russian dides have the stripes on the anode + side

You can easily check it with your meters diode test place your black probe on the white striped side red on the other side if you get a forward voltage reading it’s correctly orientated

You shouldn’t get any scratching sounds on your volume pot that’s usually an indication of DC leaking into the audio path check all your capacitors have good solder joints

 

[Barry]

+1 Billy

[Ape Chimpenson]

Hey Billy and Barry,

thanks for the quick responses. I turned the diode around. Now it measures correctly. I also resoldered all capacitors. The problem persists. In my initial post I forgot to mentione I get a loud bang sound, when using the footswitch.

[Billy]

Check C9 is the correct value and has good solder joints

I can’t see if your pots have plastic covers on them if not check that the bare metal rear of the pots isn’t touching any solder joints especially the tone pot if that’s shorting to anything it’ll affect tone and volume

Try adding a jumper between 3PDT lug 1 top left and lug 6 bottom middle

Now and again you’ll get builds that have switch pop and I’ve found this helps even though this circuit has a pulldown resistor R1 so perhaps reflow R1 first then try the jumper

 

 

 

[Barry]

Check and verify the pinout configuration of the Mosfets you are using because sometimes they can be different between manufacturers. See this article for what I am referring to: https://www.muzique.com/news/mosfet-pin-configurations/

You can also check your voltages of the Mosfets as well as the Opamp.

[Ape Chimpenson]

Hey Billy and Barry, thank you for getting back to me.

The pots have rubber stickers on the back, they dont have contact with any solder leads. I measured a bit today and found out that there indeed is a 9V (vs. 9.4 V directly on the 9V – Gnd) reading between Out and Ground. I removed the Mosfets and the IC but the voltage remains. Tomorrow I will reseat C9 and C10 and also check all the solder points of the power cuircuit to see if there is a short with a neighboring pin.

@Billy: You instantly mentioned the caps. Would a broken cap cause this behaviour too or just a faulty soldered one? And also are you referring to only the ones in the power circuit or also C1 to C8?

@Barry: This is just a reflection of R7. It seems this Mosfet is literally new and shiny. 😉

Thanks again for your help.

[Author]

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