PJCCS voltage check discrepancy

Noskipallwd · 2783

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Offline Noskipallwd

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on: April 22, 2012, 10:59:53 AM
Hello, finished the stock Quickie this morning, voltage checks were fine and worked great on the first try. Installed the PJCCS this afternoon, have a problem with the voltage check.
IA/IB 37 volts expected 37-38
A6/B6 19-21 vdc expected. A6=37.2 vdc B6=19.2
A5/B5 expected 2 vdc. A5=4 vdc B5=2 vdc.
So one is double the other on the tube sockets, not sure where to start for this one. I am assuming it is something on the board, but everything looks ok. Would appreciate any help, thanks.

Shawn

Shawn Prigmore


Offline Paul Joppa

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Reply #1 on: April 22, 2012, 11:47:44 AM
Looks like the current source is producing too much current. Check solder joints, the resistor R1 (it might be shorted?) and the orientation of the transistor and the diode.

If that does not resolve it, post the voltages at each terminal of each component on the PC board. More data = better diagnosis!

Paul Joppa


Offline Doc B.

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Reply #2 on: April 22, 2012, 03:49:39 PM
Yeah, what PJ said. In terms of looking at the solder joints, along with cold joints look for shorted traces or pads on the PC board.

Dan "Doc B." Schmalle
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Offline Noskipallwd

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Reply #3 on: April 22, 2012, 08:08:30 PM
Thanks Doc and Paul, found it, shorted pad. There is a reason you recommend taking a break when your tired, must have looked at that joint four times this morning and still missed the short. I understand why everyone raves about the Quickie. It is a wonderful sounding little battery operated pre-amp. I do recommend getting some Herbie's audio lab tube dampers, they help reduce the microphonics considerably.

Cheers,
Shawn

Shawn Prigmore