Speedball upgrade - small board: One LED not lighting, one V reading out of spec

[Luxifer]

Ah, I see the trace up top, sorry to have missed that.

Should I try to scratch away the solder mask, as mentioned, or should/can I just wire the damaged leg directly to the far leg of the part in Q2B, where that trace terminates?

 

[Paul Birkeland]

Either one is an acceptable workaround. 

 

[Luxifer]

I just tried wiring the two legs together by hand, but I am still reading in the mV range at 0B, with the white wire removed. Is this definitely incorrect?

If so, what do you suggest I do next?

Here is a photo of the wiring, to confirm: https://imgur.com/gallery/ZrHfWvW

 

[Paul Birkeland]

It's probably time to contact replacement parts to get some fresh parts and a new PC board.

 

[Luxifer]

Ah, I was hoping it wouldn't come to that, but fair enough.

Will I need the small PCB and all of the parts that go on it?

 

[Paul Birkeland]

Yes.

 

[Luxifer]

Ok, I emailed about getting replacement parts.

Meanwhile, I tried wiring the other two legs of the PN2907 to where their traces led. Unfortunately, that did not solve the problem, and after about 30 second of being plugged in, I heard a loud pop...

I'm not sure what caused this, and am worried I may have caused some other damage. I turned the system off, and checked the fuse, but it looked intact. When I turned the system on, the LEDs lit up, which makes me believe that the fuse must not have popped. Something has changed, however, as now all of the wired spots on the small PCB, 0A through to 0B, read very close to 0mV.

I feel like a huge idiot now, but thought that it might have been another leg of the PN2907 that had a bad connection, and that I could troubleshoot that by wiring, using the traces as a guide.

Do you have any idea what might have happened? Do you think that whatever damage I caused is confined to the small PCB, or might I have affected something else?

 

[Paul Birkeland]

I would recommend putting the 22K resistors back in.  Please consider that small PC board ruined and promise me that you'll throw it away. 

 

[Luxifer]

Haha, I promise. I have already ordered the replacement.

If I put the 22k Ohm resistors back in, should I just run all of the voltage checks for the stock final build?

 

[Paul Birkeland]

Yes, do recheck the voltages.

-PB

 

[Luxifer]

I am pretty sure I cut the leads to the resistors too close to the resistor body to re-use them. Unless there is some technique to re-attach wires that doesn't leave them brittle? I tried to solder them, but I was soldering between two flat faces, and the result was very brittle.

Are there any important specifications to the resistor, besides it being 22.1 kOhms? I can likely find one in the city I'm in, and test using that.

 

[Paul Birkeland]

20K-24K is going to work fine.  I'd look for a resistor that's around 1/2-1W.

 

[Luxifer]

Tested with some 22 kOhm resistors, and all was good, so I went ahead with the replacement part build, installed the rest of the Speedball, and everything is working perfectly.

Thanks so much for your help!