Failed Final Voltage Check

[figby]

Passed the resistance check, but failed the voltage check. I've walked back through the build, checked solder joints, etc. but can't find the issue. Any thoughts on where to look?

1. 365 VDC (-20mv)
2. 395 VDC (0)
3. 0 VDC (0)
4. 0 VDC (0)
5. 0 VDC (0)
6. 58 VDC (40.2mv)
7. 170-230 VDC (-.9v)
8. 0 VDC (0)
10. 0 VDC (-363mv)
11. 0 VDC (0)
13. 0 VDC (0)
14. 170-230 VDC (206.8v)
15. 58 VDC (60v)
16. 0 VDC (0)
17. 0 VDC (10mv)
18. 0 VDC (0)
19. 395 VDC (395v)
20. 365 VDC (365v)
21. 58 VDC (38mv)
22. 58 VDC (38mv)
23. 0 VDC (0)
24. 58 VDC (38mv)
25. 58 VDC (38mv)
26. 0 VDC (0)
27. 390 VDC (0)
28. 0 VDC (0)
29. 0 VDC (0)
30. 398 VDC (409v)
31. 399 VDC (402v)
34. 392 VDC (394v)
35. 0 VDC (0)
36. 58 VDC (61v)
37. 58 VDC (61v)
38. 0 VDC (0)
39. 58 VDC (61v)
40. 58 VDC (61v)

[Paul Birkeland]

Did you plug one of the 2A3s in with one or both of the fat pins in the wrong holes?  If so, you're going to need to check the 130 Ohm 2W resistors in the power supply to see which one(s) you cooked.  The socket contacts may also need to be bend back together a little bit to grab on the skinny pins again.

[figby]

The resistor between 27L and 30L is indeed cooked...thank you!

I double checked and I hadn't plugged in either 2A3 incorrectly, so that's a bit worrying that the issue might be hidden somewhere else. In the meantime, I'll put in a request for some replacement 130 Ohm 2W resistors and continue to check the circuit for possible shorts or mistakes until they arrive.

[Paul Birkeland]

A backwards cathode bypass cap around the 2A3 socket on that side would also cause similar issues. (the 220uF/250V by the socket)

[figby]

Found it!

I didn't clip a drain wire close enough and the stub had worked its way up and was in contact with the red wire from 27U where it connected at IA on the bottom of the PCB. Absolutely no idea how it managed to get up there but I clipped the drain wire stub flush and repositioned the twisted pair wire. Replaced the resistor (again) and it passed the voltage test without a problem. Listening to it now - sounds amazing.

Thank you for the assist!

[Paul Birkeland]

Good catch!  Debris can be one of the tougher issues to track down. 

-PB