Driver testing failure

[Jamus]

Paul, no worries on the mixup I'm just grateful for the help!
Kreg A = 0
R3 = 250 and 5250 ohms
-reg = 8800 ohms and slowly rising
Ground and -reg are the same
I resoldered both ends of R3 multiple times, and get the same reading at -reg. Could then be an issue with the board/terminal preventing the connection? I must have touched up R3 a dozen times since it was first suggested as the likely source of the problem.
Thanks again for helping out.
Jamus

[Paul Joppa]

Those look better - presumably the trimpot is set to250 ohms, very close to one end of its range. The only anomaly is that one end of R3 should be connected to -reg.

On the back side of the PC board you can see the trace that connects the end of R3 closest to the 431 chip to one terminal of the Cc capacitor and from there to -reg. From your measurements, it seems clear that something is wrong with that connection. The total length of that trace is barely 1/2 inch - I'd say we have narrowed it down pretty close ...  :^)

If you can't find it from that, can you post a photo of the back side of the board? Maybe getting more eyes on it will help.

[Jamus]

Okay, I think I see the problem. It really helped knowing where to look so thanks Paul for helping narrow it down within 1/2 inch!

It appears to me that the trace between R3 and Cc is not complete (bottom of the image). If you zoom in on this picture you can see a small notch in the trace. The metal around the Cc terminal is also incomplete.

Am I seeing that right?

[Doc B.]

Yup looks like it is open right there. Easiest solution is to make up a wire jumper that reconnects the disconnect.

[Jamus]

Just so I'm clear, jumper from R3 to Cc?

[Jamus]

R3 hole is too small to fit a second wire through. Any other options?

[Doc B.]

You can carefully scrape the green solder mask from the trace and tack solder the end of the jumper to it. The soldering also needs to be done with some care so the trace doesn't lift off the board.

[Jamus]

I installed the jumper tonight and sure enough that did the trick! Now getting the same resistance at R3 and -reg, powered up and voltages are in spec, trip pot is trimming, all is good in the world.

This was a long strange detour and I couldn't have navigated it without the help of PJ, Josh, PB, and Doc B. Many thanks for sticking this one out!

Best,
Jamus

[Doc B.]

Awesome! We will be sending out a replacement for the defective board tomorrow.