Installed MJE350 transistors backwards on speedball upgrade

[JulianBaynes]

I built the base crack without issues and have been listening to that for over a week. When putting the speedball upgrade together I installed the MJE350 Transistors backwards on the small board. I didn't notice this until I did the voltage checks on the small board. I have since removed and correctly installed the transistors. The lower two leds illuminate, but the upper two(closer to the IA and IB terminals) do not. These are my current voltages:

OA - around 100mV
IA - 186V
B-A/B - 0V
IB - 186V
OB - shows an open loop, climbs into the 100s of mV and returns to open loop. This process cycles.

I'm sure I need new MJE350s and probably two new leds. Am I better off getting a whole new small board? Hoping I didn't break anything on the crack itself.

[Paul Birkeland]

A replacement small board isn't a bad idea.

If you want to repair it, a new pair of MJE350s and a new pair of PN2907s should do the job.  The LEDs do not need to be replaced.

-PB

[JulianBaynes]

A replacement small board isn't a bad idea.

If you want to repair it, a new pair of MJE350s and a new pair of PN2907s should do the job.  The LEDs do not need to be replaced.

-PB

Thank you for the reply. So you think I'm better off ordering a new board and set of parts than desoldering and installing new transistors?

[2wo]

What I would do is cut the transistors off close to the plastic. Now you can desolder one leed at a time, putting less stress on the PCB. When you are done you will be in a better position to judge if the board cad be saved...John

[Doc B.]

The issue with component level repair is that a lead (particularly the rectangular transistor leads) can catch and pull up a trace when being pulled out. This is most likely if the lead is pulled after the reheated solder begins to cool. Solder wick or a desolder pump will help to get that excess solder away from the lead so it can be pulled out without yanking up a trace.