Incorrect voltages after installing Speedball [resolved]

[Paul Birkeland]

Okay. Do you think it could be the switch, though? 

The power switch?  No. 

Also, I have a ground wire between Terminal 4 and 14U instead of 22L. That's still fine, correct?

No problem there.

[Adelz]

Oh, it isn't? The revision in the Crack manual says it's fine and nowhere does it mention that the revision will not work with the Speedball. 
 
Anyway, I switched that ground wire from 14U to 22L. That didn't fix the problem. I really don't know what to do next.

[Paul Birkeland]

Sorry, I mistyped there.

I have repaired several Cracks recently that had the symptom you are describing.  All of them had cold or loose solder joints that needed to be reheated to function quietly.

-PB

[Adelz]

Ah, okay. Do you think any resoldering of the PCBs will be necessary or does the buzzing mean that it is most likely a transformer/capacitor issue?

[Paul Birkeland]

Ah, okay. Do you think any resoldering of the PCBs will be necessary or does the buzzing mean that it is most likely a transformer/capacitor issue?

Solder joints on PC boards are generally much easier to inspect (there is a lot of online information about soldering PCB's), but it won't hurt to reheat them also.

-PB

[Adelz]

I've resoldered pretty much everything and the buzzing is unchanged. 
 
I really can't tell what the problem is. Also, thought I'd mention I have the resistor mod for the pot installed but other than that everything is completely stock.

[Adelz]

I removed the Speedball upgrade and it seems that the amp is working, so it appears that the problem is not the power supply. What are the most common mistakes to look for on the PCBs? Also, is it possible to install each of the PCBs one by one in order to see where the problem is?

[Paul Birkeland]

You can put just the small boards in, then run the amp with the 3K resistors in place (and the 22.1K resistors removed).

-PB

[Adelz]

The buzzing is back with only the small PCBs in place; I guess that narrows down the problem.

[Paul Birkeland]

Is this noise that you get in both channels?

[Adelz]

Yeah, I'm getting the noise in both channels. Even after resoldering I'm still getting it; not sure what's wrong.

[Paul Birkeland]

Can you try connecting a source and listening to the amp?  With unshorted inputs, you may end up getting some noise.

-PB

[Adelz]

When plugged into my source I can hear music over the buzzing. The music is not distorted at all and the buzzing now appears to be softer in the left channel in comparison to the right. Right now I have the 3K resistors in place of the large PCB and the two small PCBs in the amp.

[Adelz]

After a day of troubleshooting the problem is still exactly the same. 
 
It's definitely not the power supply or anything that's in the stock Crack, as that works fine. It seems that the buzzing is being caused by the small PCBs but after resoldering every joint on them the problem remains. What should I do next? 
 
Edit: With the large PCB and the 22.1K resistors between the red wires meant for the small PCBs, the amp functions perfectly, so I'm assuming that the connections of the red wires to the terminal strip are fine. All four resistors on the small PCBs measure correctly, even when measured from their solder joints on the boards. All four LEDs glow brightly and are in the correct orientation. At this point I'm assuming the problem is either one of the MJE350 transistors or a 2N2907. What is the most accurate way to test them?

[Paul Birkeland]

If you believe the transistors are the problem, then they should be replaced.  It's possible that one set of transistors was damaged from the R1 swap, but not both sets. 

-PB