No voltage reading D1, D4 with DC Filament Upgrade

[Twodawgzz]

All voltages and resistance levels match up with specs.  Could a component be faulty?  When I built my Crack headphone amp, it came with a dead tube (I don't remember which one, but I think it was the 12AU7).

[Paul Birkeland]

It's likely a loose connection, maybe even something as simple as a loose speaker wire. 

You can swap the 2A3 tubes from side to side and the 12AT7s from side to side to rule them out.

Actual components like resistors, transistors, and capacitors will tend to produce wildly off DC voltages and smoke when they fail, so you definitely do not want to start pulling parts because you think one is bad.  This kind of effort will generally make more problems that also need to be solved.

[Twodawgzz]

Swapped tubes and that didn't change anything, so tubes are fine.

Next step was to flip the chassis over and poke around with a wooden skewer to hopefully find a poor connection.

When I flipped the chassis over and turned everything on, the problem was gone, and the amplifier played both channels just fine.  Then I flipped it back upright, and everything was still fine.

So I guess I'll proceed with the next upgrade and look for a bad connection later if the problem resurfaces.

[oguinn]

Did you poke around with the chopstick even though it was working? That might save you from having to do this again when the problem resurfaces

[Twodawgzz]

Poked around and found the intermittent contact at C3.  Probably needs to be resoldered.

Thanks again for the help everyone.