Failed Final Voltage Check

[Paul Birkeland]

A broken wire could cause some issues, though one wire is unlikely to cause all of what you're seeing.

-PB

[Dhouse7516]

Okay, thanks. I am at a loss. I went back over the board and the tube terminals again, re-flowed a couple of additional joints, replaced the shunt board wires and am still getting very similar readings:

IA: 284
IB: 285
OA: 280
OB: 152
KREG A: 6.38
KREG B: .45

Unless you have any additional thoughts, I will reach out to the address you provided earlier and request a repair. Please keep me in the loop as I really want to know what the issue is here and learn from this! Thanks for all of your help.

[Dhouse7516]

Paul, as I was going back over the board just now, I noticed that the R3 resistor on the B side has a large crack in the end. I tested it and it's bad (no resistance). If you think that this might explain the issues I'm having, I'll order another one and replace before sending in for repair. Thanks.

[Paul Birkeland]

It certainly wouldn't hurt to give that a try.

[Dhouse7516]

Thanks, I assume this is a suitable replacement?

https://www.digikey.com/en/products/detail/stackpole-electronics-inc/RNF14FTD2K49/1706690

[Paul Birkeland]

Sure, that will work nicely.

[Dhouse7516]

Thanks, Paul. I need to order some additional single-core wire as well. It’s 26awg, correct?

[Paul Birkeland]

22 AWG solid is recommended.  The kit should have come with some extra wire.

[Dhouse7516]

Thanks, I used up the extra when I was re-wiring the D socket and the board

[Dhouse7516]

I received the replacement R3 resistor today that we discussed above. It's physically smaller than the one supplied with the kit (see picture). I assume that's because it has a different tolerance or wattage. Maybe a dumb question, but do I need to be concerned about this? Do I need to replace the A side R3 with a matching resistor (I bought two) as well as the B side, which is the one that is damaged? Thanks.

[Doc B.]

Just replace the one that needs to be replaced. They function indentically.

[Dhouse7516]

Excellent. Thanks, and will do.

[Dhouse7516]

So this is strange. I tested the new resistor before installing and it passed at 2.49k ohms. After I installed and soldered it to the board, the resistance check at the leads (on both sides of the board) is failing. I’m getting readings of 10-11 ohms (not K ohms). When I test the R3 on the A side at the leads I am getting 2.49k ohms. Does this suggest any obvious issues to you?

[Dhouse7516]

The most obvious issue to me is that I might suck at soldering PCB boards.

[Paul Birkeland]

That would most likely be a shorted 431 regulator.