Low buzzing, then music stopped [resolved]

[Bottle Rocket]

So, I had the Beepre up and running for several hours.  During that whole time there was low level buzzing coming from both channels.  Then the music stopped and only buzzing could be heard. 

I took a look under the hood and the LEDs on the PC board above the A 4 pin socket are no longer lit up.  These are the two LEDs on the B side of the PC board.  The A side LEDs work.  I did notice a stray wire from nine pin socket C7 making contact with C6 and clipped that lead.  Checked everything else around and under the PC board in question.  Re-soldered a few joints and everything looks okay (other than those LEDs not lighting up).  Resistances seemed to check out. 

However the voltages are not in range:

1- 14.35
2- 156.3
3- 0
4- 14.35
5- 14.50
6- 157.7
7- 0
8- 0
9- 14.42
10- 191.1
11- 99.0
12- 0
13- 0
14- 0
15- 187.2
16- 5.03
17- 96.7
18- 0
19- 9.81
20- 0

The other voltages after these seem to be in range. 

Any suggestions??

Thanks,
Michael

 

[Paul Birkeland]

What's your line voltage?

What voltage do you have on each channel at:

POS IN
POS OUT
IA
OA
OB

-PB

 

[Bottle Rocket]

A Side:

Pos In: 16.62
Pos Out: 14.42
IA: 189.7
OA: 161.5
OB: 158.3

B Side:

Pos In: 13.65
Pos Out: 9.81
IA: 185.4
OA: 96.7
OB: 94.4

 

[Paul Birkeland]

Swap 300B's to see if the POS OUT voltage switches sides. 

 

[Bottle Rocket]

Switched the 300B's and looks like the POS OUT voltages stayed the same for both sides. 

 

[Bottle Rocket]

Also seems whichever 300B tube is on the A four pin socket, isn't lighting up now. 

 

[Paul Birkeland]

I'd have a close look at the wiring of those paralleled 10 Watt resistors up at the front of the chassis on the offending side.  The high voltage coming out of the regulator is unusual, but perhaps there's just no load on it. 

I would also expect exactly the conditions you described if the jumper from NEG OUT to -reg, or -reg to the center of the 9 pin socket, or the black wire that leaves that socket up to the front of the chassis has a flaky joint.  That would remove the ground reference from the board itself, which would allow for some strange voltage readings and no glow from your 300B on that side.

-PB

 

[Bottle Rocket]

Paul, you are the man! I re-soldered all of the joints you mentioned and now everything works! Finally have everything hooked up (BHDAC->Beepre->Paramount->Orca Minis) and man does it sound good. Very, very happy. Thanks for all of your assistance.

 

[Bottle Rocket]

Haha, Grainger you are right about that!  Sound is awesome and really fills my living room, which is a decent size.  Loving this combo!