Silent UniCab

[noahjbauch]

Hey guys,

I'm building a UniCab and am having problems getting it to... well... make any sound at all really. I started tracing the signal with my audio probe (something I'm very new to) and I think the TL072 or TL074 might be the issue. Can anyone tell me which pins I should be able to hear signal from? If I remember correctly, I could only hear it from 1, 2, 3, and 5 of the TL074 but none of the 8-14 side. And I think the TL072 was similar—certain pins in 1-4 but none of 5-8. I got pulled away in the middle of working on it, so I didn't really check everything in the circuit yet. But if anyone has info on where I should be able to find good signal from either of those ICs, it would help me out a lot. Thanks!!

 

[fig]

hang on...technical difficulties

 

[noahjbauch]

hang on...technical difficulties

Thank you so much for posting this!! If I'm thinking about this correctly, does this mean I should be able to hear signal from all pins of the TL072 except 4 and 8, and all pins of the TL074 except 4 and 11?

 

[fig]

Looking at the schematic..yes. I'd check around the TOP pot & R9/R10. Also check power to both cheeps.

 

[noahjbauch]

Looking at the schematic..yes. I'd check around the TOP pot & R9/R10. Also check power to both cheeps.

Thank you! Should the power to the chips be about 9V?

 

[fig]

Yes, that's correct. You can see the pins marked at Vcc, which is supply level voltage.

 

[music6000]

Hey guys,

I'm building a UniCab and am having problems getting it to... well... make any sound at all really. I started tracing the signal with my audio probe (something I'm very new to) and I think the TL072 or TL074 might be the issue. Can anyone tell me which pins I should be able to hear signal from? If I remember correctly, I could only hear it from 1, 2, 3, and 5 of the TL074 but none of the 8-14 side. And I think the TL072 was similar—certain pins in 1-4 but none of 5-8. I got pulled away in the middle of working on it, so I didn't really check everything in the circuit yet. But if anyone has info on where I should be able to find good signal from either of those ICs, it would help me out a lot. Thanks!!

Post Good pictures of Front & Back of PCB including Footswitch, In & Out Jacks!

 

[noahjbauch]

So clearly it's been a while, but I'm finally finding time to get back into this build, and something I found today is that pin 12 on the TL074 sounds fine, but pin 13 sounds like trash, all the pins on the punch and gain knobs are silent or sound crappy and I think everything else after that is just silent. Does this mean something is wrong with my TL074? That's the conclusion I'm starting to come to...