Troubleshooting spontaneous Crack failures.

[tjessen]

Hello,

I have a Crack amplifier, about 2 years old that only once in a while, will fail to power up for me. The switch will be on however the tubes and leds on my speedball board and between the tube socket fail to light. To solve this, simply grounding terminal 1 on the transformer causes it to resume normal function. I was wondering what might be going on.

Also, a loud audible hum is presented by my headphones when the plug is inserted with the potentiometer turned completely down (and the Crack on), but not when the pot is turned up some. EDIT- I should mention this hum disappears as expected when the plug is fully inserted.

Thanks!

[Paul Birkeland]

To solve this, simply grounding terminal 1 on the transformer causes it to resume normal function. I was wondering what might be going on.

Gah, don't do that! That would be shorting the hot incoming AC to ground, yeow!

There's certainly something flaky with your AC input wiring, I'd tug on all the wires to be sure none of them are loose.

[tjessen]

I've checked all the wires and re soldered most of the joints. It's very odd.

[Grainger49]

Sometimes you have to just break out the meter and measure resistance from the start of a circuit to the end.  Something has come loose. 

What you need to do is start at the output of the diodes and measure resistance to the terminals or tube pins (not to the solder joints) where the voltage goes.

Do you understand the difference I am trying to point out?