Sex 2.1

[proud indian]

I have a cracking noise from my right channel. Did all the usual , tube swap, solder etc. Finally I found that pin 1 of the grid has a voltage of 32mv but the right channel has 180mv.
On starting the amp , it is low and then it slowly starts going to 180, and then the crackling noise starts.
Changed caps and resistors .
Need help.

Shreekant

 

[Paul Birkeland]

You can test your hypothesis by temporarily soldering a wire jumper across the 249K next to pin 1 (it's behind the 680R 3W power supply dropping resistor). The 180mV of grid voltage will be completely shorted to ground, and you'll only end up hearing what's going on with the output section. 180mV doesn't really raise a lot of concerns, but if you see that voltage wandering around a fair amount, it might.

Are you able to set this noise off or change it at all by poking around in the circuit with a wooden chopstick?

 

[proud indian]

No. The noise comes back. Strangely if I do some solder etc, it takes a while to get back. But it does. Another thing is that it is not increasing in volume. All the time with what ever I do, it gets back . It doesn't happen on start up. It shows up after warm up.

 

[Paul Birkeland]

The noise persists with the 249K resistor shorted?

Do the tube socket pins feel tight? Have you ever sprayed Deoxit into them?