SOLVED Thermionic Distortion

[Musician78]

I just put together a Thermionic Distortion and everything works great. Except the bass control. I have checked the pot, replaced the pot, checked the two resistors, (R18 and 19 if memory served me right), replaced the two resistors, checked the cap (c17 if memory serves me right), replaced it. I've checked all my solders with a magnifying glass... I simply cannot figure it out. This is far from the first pedal I've ever built so I am not a novice with the soldering iron. I have never had such trouble trouble shooting a circuit before.

Is there anyone who can help?

 

[zgrav]

Use your DMM and audio probe to confirm you have a signal reaching terminal 3 on your bass pot, and a connection to ground from terminals 1 and 2 of the bass pot. if those connections or good you need to check the part values again.

 

[Musician78]

Do I need an audio probe or can I just use DMM? How exactly do I do this? Sorry... anytime I’ve trouble shot it was always testing actual components. I’ve been lucky and always found the issue. Lol.

 

[Musician78]

I actually just learned how to make an audio probe. It look a lot less time consuming than checking each component. Lol!!! I will try this. Thanks!

 

[zgrav]

You will find that the audio probe is a great debugging tool.

 

[Musician78]

Use your DMM and audio probe to confirm you have a signal reaching terminal 3 on your bass pot, and a connection to ground from terminals 1 and 2 of the bass pot. if those connections or good you need to check the part values again.

So I used my audio probe. There is no signal going to any of the terminals of the pot. There is signal at both resistors. Capacitor c17 has signal at the top solder (when board is oriented correctly but nothing from the bottom solder. I’ve resoldered, changed the cap, etc. any suggestions?

 

[Musician78]

You will find that the audio probe is a great debugging tool.

I fixed it!!!!!!!

 

[zgrav]

Congrats! What was the problem and how did you fix it?

 

[Musician78]

Congrats! What was the problem and how did you fix it?

I used the audio probe as you suggested and realized that I was getting signal to c17 cap but not out of it. I changed it before I started asking and the problem was still there. When I realized that was where the issue was I changed it AGAIN and it worked. So two bad caps. Brand new. So unless I somehow killed them whilst installing them, the QC was terrible. Lol!!!

 

[zgrav]

Glad you were able to isolate the problem and fix it.

 

[Musician78]

Glad you were able to isolate the problem and fix it.

Thanks for your guidance!