C20 smoking

[swemoll]

Hey guys,

Just finished stuffing my first C84 preamp, and upon power-up, C20 started to smoke. I've shut it off both times before serious damage, but I'd like to know where to begin looking before troubleshooting. What could be causing C20 to smoke? I'm 95% sure there are no shorts, and all C's have been placed with correct polarity.

Thanks in advance...

- Landon

[tpryan]

If you're absolutely sure that C20 isn't backwards, it's possible Q5 is getting so hot it's cooking C20. If that's the case, the damage is already done and you should snip out and replace Q3-Q6.

[swemoll]

Upon inspection, I realized Q2 was backwards. After flipping it, C22 is now getting hot and smelling like it's overheating (the same thing C20 was doing).

Where should I look now? Should I just replace Q3-Q6?

Thanks for your quick response!

[tpryan]

C22 doesn't have anything to do with Q2, so the problem is likely elsewhere. There's a good chance Q2 is already damaged, however. I recommend you get some help from a local tech or e-mail rma @ seventhcircleaudio.com for return instructions.

[swemoll]

Return instructions email sent.