And now, as expected, the Final Voltage test [Solved]

[Suger]

If anybody had a wager going, it's time to collect. I've failed the Final Voltage test, and, of course, am flummoxed.

So, here we are: I've added the board and all that, put in the lamps, and fired the amp. And get 3volts on the A side and 2 volts on the B side. I've been delving a little bit more, and so I get 400V at the non grounded part of the resistance in R2 on the A side, as well as at the LEDs, and at one of the pins of the MJE5731A on the A side, the one closest to the potentiometer. I get 389V at the other external pin of the MJE5731A, but only 3V at the central one, as well as at OA and onwards. So there is something wrong with my circuit somewhere, probably in the part that is beyond the MJE5731A on the A side, but I can't figure out where, and so, here I am again, asking for help.

 

[Paul Birkeland]

What DC voltages do you have at:

IA, OA, IB, KregA, KregB?

 

[Suger]

IA 402
OA 3
IB 3
Kreg A 3
Kreg B 3

I know it's a solder somewhere, if only I could locate it.

 

[Paul Birkeland]

How about the DC voltage at -RegA and -RegB?

 

[Suger]

0 for both, I'm afraid.

 

[Paul Birkeland]

I would unscrew the board and carefully tilt it up so you can show a pic of the bottom side, as well as how it's wired into the amp.

 

[Suger]

Are these good enough?

 

[Paul Birkeland]

For all the solder joints other than the ones with LEDs, you can apply a whole lot more heat.

On the 9 pin socket, it is not permissible to wrap connections around the sides of the socket pins.  You can wrap them up and over, and there's a little depression in the top edge of each socket pin that will keep the leads in place for soldering.

The presence of proper ground and proper IA voltage but nothing on OA either means you have a major short pulling OA down, or soldering problems.  The short condition would also come with snaps, crackles, and pops, so I would be more inclined toward the soldering issues.

 

[Suger]

Thanks.

No crackles or pops, so I'll redo the solderings. I'll start by redoing all the 9 pin socket connections, then move on to the board and will let you know.

 

[Suger]

So, as it turns out, I'd mounted a 1003F resistor (so 100Kohms) instead of a 90R9F resistor (90.9 ohms). I've made the change, and voilà.

Thanks again for the support.