Voltage check error

[polarpigs]

My crack speedball had been picking up a buzz and been crackling in the right channel for a week so I decided to reflow the solder. In the process I'm pretty sure I messed something up but I have no idea what it is now.
There is no sound coming through to the headphones and the 2 red LEDs on the octal socket aren't lit.
The 12AU7 and 6080 are lit properly in both halves and the rest of the LEDs on the speedball are properly lit.
These are the wrong voltages:
Ground to:
T1: 0V
T5: 170V
T7: 53.7V
T9: 170V

 

[Paul Birkeland]

Can you unplug the 6080, then recheck terminals 1-5.

Having 0V at terminal 1 on a Speedball can mean that the center leg of the MJE350 transistor needs to be reheated.  Having 170V at T5 generally means that the R1 resistor on that half of the small Speedball board (or that small Speedball board for older kits) has the wrong value.

Having both of these creep up after reflowing joints would also make you want to check for any shorts both on and off the boards.

-PB

 

[polarpigs]

Unplugged 6080

T1: 0V
T2: 222V
T3: 0V
T4: 222V
T5: 220V

The only lit LEDs are the 2 on the Speedball A board.

 

[Paul Birkeland]

Do you have the new Speedball with the single small board up front?

Were your voltages ever in spec after the initial installation of the Speedball?

 

[polarpigs]

Regarding initial voltages, I'm pretty sure that they were in spec. It's been 2 years since I've built this so I'm not 100% sure.

I'm not sure about the board, here's an image of the underside of the crack.

 

[Paul Birkeland]

How about unscrewing the small boards and taking pictures of the bottoms, as well as what's underneath the boards.

-PB

 

[Doc B]

Yup, good call. If you were reflowing pads on the boards you may have created a solder bridge that is shorting something out. A pic of the bottom might help spot a bridge.

 

[polarpigs]

SB Board A underside:

Board B:

 

[Paul Birkeland]

Can you measure the DC resistance of the R1 resistors on each small board and let me know what you see?

 

[polarpigs]

Jumps around a little but settles on 235Ω for both the R1 resistors.

 

[Paul Birkeland]

Can I see the build under the boards?

It's very unusual that both the small boards wouldn't work of they were functioning before.

 

[polarpigs]

I hope these are clear enough

 

[Paul Birkeland]

The only advice I can offer is to reflow the joints on the PC boards. It actually looks like a little tiny bit more solder wouldn't hurt, and that the center legs of the MJE350 transistors could use quite a bit of extra heat.