Right channel not playing after speedball upgrade [resolved]

[LubedTuba]

Hi all,

I installed the Speedball upgrade and all the resistance and voltage checks were within the expected ranges for both the small and big circuit board. However, after I tried plugging it into my rig, I heard a loud pop in the left channel. After I started a track, I realized that music was only coming out of the left channel. I plugged my headphones into my phone and both channels worked fine...suggesting something is wrong with the amp.

I measured the resistance and voltages again and this is what I got (values that don't fall within the expected range are denoted with a *):
Small Circuit Board:
OA: 68.4 V
IA: 168.3 V
B-A/B: 0 V
IB: 168.1 V
OB: 164.9 V*

I then followed the diagnostic flow chart and measured the R1s on the small circuit board and get a reading of 3.6 MOhms despite mounting everything correctly. Furthermore, only the right LEDs are lit however the 12AU7 still glows.

[LubedTuba]

I don't know if this helps but here are voltages for the big board as well:
OA: 163.5 V*
OB: 98.5 V
G: 0
B+: 169 V

It might be hard to tell from the picture, but all the LEDs are on.

[Natural Sound]

redacted

[Paul Birkeland]

I would recommend unscrewing the small board and looking around for what might have popped. 

[LubedTuba]

The underside of the board looked fine. I went back and re-soldered everything on the small board (also went ahead and re-soldered all the red wires by the headphone jack). I'm happy to say that all voltages are normal and everything is working as intended!

Thanks for your input! Have a happy new year!

[Deluk]

When I look at these boards, as I have at many others, it surprises me that the operator is happy to accept the solder to show a nice meniscus only on one side of the eyelets. It's best to also solder on the top side of the board to ensure that the legs of the component are full soldered to the complete eyelet. It only takes a few seconds and will greatly increase the chance of a good reliable joint. When I was working I would get boards back from inspection with any looking like this marked for resoldering. Boards in aircraft black boxes have to be reliable.