Weird Terminal 9 voltage on speedball + dead left channel [solved]

[FairDinkum]

My Crack works ok before the installation of Speedball. After installation, the voltages appear fine except for terminal 9, which starts high (180s) and gradually decrease. Upon listening, the left channel is dead.

There were 2 incidents during voltage checks where there were sparks: the first time when the negative (black) test probe with alligator clip tester on terminal 12 came loose and touched terminal 13. In the second incident, I was shaking too much while testing terminal 7. I shut down the amp right away. I hope I haven't short circuited anything.

Your help is much appreciated.

[Strikkflypilot]

The experts are here soon to help, rest assured.
Just a thought, a short between B5 and B6? Happens for example if leads are too long, at the sockets they might rather easily shift. Pictures of the octal sockets solders and the adjacent termnal strip available?

[FairDinkum]

Rightio I'll check and take photos.

[FairDinkum]

Here are the photos of the octal socket and terminal 9. I've also attached the voltage readings.

Meanwhile, I'll reflow 9U.

[FairDinkum]

Did an ohm check on terminals 7 and 9. Both appear to be increasing (charging) but the former is showing 6-ish mega ohms and climbing while the latter starts at 1ish. Not sure if this is normal. The test was performed after I've reflowed terminal 9. Near in mind I've done the grounding mod on the volume pot per the sticky thread in this forum.

Thanks for any suggestion you might have.

[FairDinkum]

More photos of the octal socket and the terminal strip.

[FairDinkum]

Plot twist! One of the LEDs on the big PCB is not working.

[Paul Birkeland]

Try reheating the center leg of the TIP-50 feeding T9.

Also, just to double check, you did install the thermal pads and shoulder washers on the TIP-50's?

-PB

[FairDinkum]

Try reheating the center leg of the TIP-50 feeding T9.

Also, just to double check, you did install the thermal pads and shoulder washers on the TIP-50's?

-PB

OK I'll reheat the center leg for both TIP-50. And yup I've installed the clear thermal pad and washers.

[FairDinkum]

Reheated the center leg of the TIP-50 closest to the volume pot on the right. A few seconds after switching on, both LEDs are now not working and there's some sparking under the PCB. I switched it off immediately.

[Paul Birkeland]

Sparking under the PC board would indicate a loose connection or a loose solder blob shorting out components. 

[FairDinkum]

Ok. What I'm going to do is to completely detach the main PCB and troubleshoot from there. How do I check to make sure the components are working, especially the TIP-50? Just resistance checks?

[Paul Birkeland]

You can measure the resistance between each pair of pins.  When they fail, they fail shut.

Also check the 2N2222A.

-PB

[FairDinkum]

Hmm I'm not sure where the problem is under the PCB (right side of the picture). Here's a photo of the soldering job of the TIP-50.

[Paul Birkeland]

Throw it back in and check voltages.

-PB