Need to identify version and get manual for used Crack + Speedball

[Paul Birkeland]

With the amp flipped over and the 9 pin socket closest to you, those front terminals are numbered 1-5, then the terminal strip behind it is numbered 6-10.

Can you provide DC voltages for terminals 1-10?

The 6080 is most likely OK.

[manicmidget]

Rounded to the nearest 1V:

1 - 79V
2 - 193V
3 - 0V
4 - 193V
5 - 76V

6 - 0V
7 - 111V
8 - 0V
9 - 0V
10 - 0V

[Paul Birkeland]

There's a pretty messy bit of soldering on terminal 9 in your photos, and that certainly won't help.

[manicmidget]

Yeah, unfortunately I bought this used/pre-assembled so the solder work is not as nice as I'd like. I'll resolder that joint and get back to you, thanks again. (I'm still hoping I don't have to redo everything...)

[manicmidget]

It wasn't the solder joint! Perhaps one of the components it's connected to is burned out?

[Paul Birkeland]

The PC board with the heatsinks is symmetrical, so you can try rotating it 180 degrees.  If the 0V terminal moves to terminal 7, then there's an issue on the board.  If that 0V stays put, something else is amiss.

[manicmidget]

What's the easiest way to rotate, i.e., which joints should I desolder?

[Paul Birkeland]

You can just remove the wires on the "O" terminals and leave the black and red wires in place, then rotate the board 180 degrees and reconnect the "O" wires.

[manicmidget]

Voltages stayed the same.

Could it be the capacitor? No visual bulging or leaking though.

[Paul Birkeland]

You could try a different 6080 if you like just as a point of reference.  Still, I would expect a bad solder joint or broken wire to be the most likely culprit for your issue. 

A cap shorting things down like that would get hot, the top would swell, then it would explode. If this hasn't happened, I wouldn't worry about the cap.

[manicmidget]

Okay, good to know. Do you have any suggestions on any particular wires or circuit subsections to start with? Or should I just work outwards and keep testing?

I did take a chance and try the amp with my headphones, and the left side doesn't work. (Swapped L/R and right side didn't work.)

[Paul Birkeland]

No, please don't try to use an amp that doesn't pass its voltage checks.  Failing the voltage checks means that the amp isn't working and could damage your headphones and we certainly could have told you that one channel isn't going to work with 0V DC on terminal 7. 

If you have a really inexpensive pair of headphones that you can use for testing, you can poke around the circuit with a wooden chopstick and music playing to see if there's a spot where poking restores operation of the missing channel, but definitely only do this with the least expensive pair of headphones possible.

[manicmidget]

Not to worry, I did use my testing pair of headphones that were free from an airliner. I'll try your suggestion with the chopstick, then if all else fails I'll re-solder every connection and report back.

Thanks so much!

[manicmidget]

Quick sanity check. Aren't both sides of the tube supposed to be glowing? I would assume so given symmetry, but the ring on top of only the non-glowing side gives me pause.

[Paul Birkeland]

On a 6080, I would look at the bottom of the internal structure to see if both halves are glowing.  If you're absolutely sure that one side of the 6080 isn't lighting up, then that would point to a defective tube.