Speedball help

[antjuneau]

I just upgraded my Crack with the Speedball and I'm having an issue. All of the LEDs are lighting up except for the one that connects A8 to the centerpin. I'm getting audio through the left channel but silence in the right. Also, the voltage across the A3-to-centerpin LED is 1.5 V whereas the voltage across the A8-to-centerpin LED is 12 V. Any ideas on what the problem could be?

[Paul Birkeland]

The 12V at A8 can indicate that A7 isn't properly referenced to ground (check to see if there's any DC voltage at A7), or simply an LED that may have endured some physical trauma and is damaged.

It's completely harmless to run a wire jumper from A3 to A8 to get you back up and running.

-PB

[antjuneau]

I tried the jumper and it's still not working. I should mention that I am getting sound through the right channel now but it's very faint. The left channel is loud and distorting but the right is very quiet, and inaudible at low volume settings. Also the two LEDs on the right channel's board are very faint and flickering.

I will switch the two PCB boards and see if the issue follows the board.

[antjuneau]

I just noticed something else - the D1 LED on the right PCB board looks physically damaged. Could that be causing this issue?

EDIT: Just switched the A & B PCB boards. The problem followed the bad board. When I tap on the 2N2907 transistor on the bad board the signal goes in and out. Even when I get audio it's distorted. I plan on ordering a new 2N2907 unless you guys have a other idea.

[Paul Birkeland]

Reheat the joints on that board.

You will not be able to damage the 2N2907 with your soldering iron.