Sundown tuneup...

[Bear]

Flux is much more likely to be an issue on a PCB amp than any PTP/lug/turret/eyelet arrangement because the traces are so dang close to each other. The symptoms kind of sound like those of "tweed disease" where on old fiber circuit board has absorbed too much moisture and the thing becomes capacitative and screws with things.

Bear

[ic-racer]

First time I have heard of flux casuing problems.
Of course I am not that experienced in tube amps.
I wonder if that stuff conducts small amounts of current?

The flux was hard and crispy, almost crystalized. Also, there was dirt and dust covering the entire board. Trapping of moisture or other pollutant may have been the ultimate cause.

I did have an experience working on a motor power supply with an oscillating circuit. The resistor controlling the oscillations seemed to go out of spec, changing the frequency of the motor-controlling oscillations. Well, when I measured everything the resistor was 'in-spec' and I was getting like 400k ohms from the resistors PC trace to ground. The rest of the board's traces gave over 1M resistance to ground. In that case cleaning the board did not seem to have much of an effect, so I wound up just putting in a larger resistor and it worked fine. But I never could see anything physical on either side of the board that could possibly be conducting, so perhaps it was the board substance itself.

I had a crazy theory about the crackling in that it was due to some 'semiconducting' property of the flux caused by a pollutant on the flux, causing a random building up and releasing of minute charge. Like a nanoscopic version of lightning.

[ic-racer]

What's a Sundown test without a Scofield style track...

http://soundclick.com/share?songid=6684297

Unlike John, I used the Red channel and no 'Rat.'

[Structo]

I don't know how I missed this clip.

That sounds really good!

How loud was it in the room? (volume)