voltage issue speedball large board [Solved]

[Gizmo1k]

been enjoying my crack quite a bit and speedball came in yesterday.  I installed the small board no issue however on the large board i got a cracking sound in the right channel as well as the top left led of the large board lights intermittently.

i pulled my 6080 tube and measured voltages again on the small board

0A - 69.8
1A - 229.2
B-A/B - 0V
1B - 229.2
0B - 65.9

i then put back the 6080 tube and got the following voltages off the large board.

0A - 70.3V
0B -49.7 (low)
G - 0V
B+ - 107.5 V (low)

 

[Paul Birkeland]

The low B+ and the problematic voltage on OB suggest it's possible that one of the TIP50 transistors isn't mounted properly.  It's also possible that you have a solder bridge between two pins of a component on the bottom side of the big PC board.  When in doubt, posting pictures can be really helpful!

You definitely won't want to run the amp for very long like this, as the 107V of B+ means a lot of thermal stress is being put on the power supply.

 

[Gizmo1k]

Here are the pics. iPhone wouldn't let me upload directly.  I had to desolder a couple wires to get good pictures.
https://imgur.com/gallery/B82c5F3

 

[Paul Birkeland]

I would lift the 2N2222 transistors up off the board a little bit, as is directed on page 22 of the Speedball manual.

You also installed the LEDs in such a way that we can't tell if they are installed in the correct direction, so there's also that...

 

[Gizmo1k]

You rock thanks.  I lifted the transistor near the problem area and i'm good to go.  thanks for the awesome support.  I wish i was better at following directions   but at least i'm learning a lot about troubleshooting.