Speedball large board voltages out of range [resolved]

[VineSerf]

After a number of weeks enjoying the stock Crack I installed the Speedball upgrade. The small board install went great, and I enjoyed a few hours of seriously enjoyable listening. Today I installed the large board, and have concerns about the voltage readings

OA - 173.2
OB - 110.8
G - 0.6
B+ - 111.8

Other than G all are out of range, with OA and OB being well more than 10% out. Should I be concerned? BTW, resistances were fine, both about 380 ohms. All LEDs light up.

[Paul Birkeland]

They are consistent and probably just fine.  I'm guessing the voltages on OA and OB on your small PC board are a little on the high side too.

[VineSerf]

Many thanks Paul for the quick reply. I was hoping you'd say something along those lines!

The small board voltages were all much closer to spec: OA at 89, OB at 82, 1A at 160 and 1B at 161. Regardless, I'm warming up the tubes now and looking forward to enjoying my new & improved Crack.

On a more general note, in addition to selling some great products, the tech support here is simply outstanding. All very much appreciated.

[Paul Birkeland]

I am also guessing that you have B+ and OA swapped.

IA and IB on the small board are wired to B+, as is B+ on the big board, so having 161V at one and 173V at another does suggest an issue. 

[VineSerf]

You nailed it: In the late hours after considerable difficulty dealing with the micro wires with aging, thick fingers, I'd crossed those two wires. Easy fix, all seems well now:

OA: 106
OB: 110.8
G: 0.2mV
B+: 175.

The change also resolved a notable unbalance between channels. With the wrong wiring the right channel was about 2x as loud as the left. All balanced now, and in fact the amp (with HD 650s) is sounding simply magnificent.

Thanks again for the great support.