A8 LED turns on and off with volume pot?

[bdr529]

This behavior appears to be temporary and eventually stays on after the system has been up for a minute or so, but I wanted to check with the forum. I don't remember seeing this before...

From a cold start both socket LEDs will come on as the amp turns on, but A8 will turn off and 'flicker' a little mostly staying off. I noticed however that turning up the volume the LED will go solid again at a specific spot in the volume. Eventually it will stay on for good regardless of volume position. A3 stays on the entire time. I am not at home but at my parents house so I don't have access to my soldering iron or dmm so this has me a little worried and I am afraid to plug in my headphones now  :-[.

What does the LED lighting up mean?

Thanks

edit: Also, the volume pot is secured tightly and the solder joints around it look solid and shiny.

 

[Paul Birkeland]

Measure the voltages at A1 and A5 while this is going on and let us know what you find.

Neither LED should light at all when the amp is immediately turned on.

 

[bdr529]

I will be able to measure it when i get home after the holidays, but LEDs do come a couple moments after flipping the switch. I was just trying to say they both come on, then one of them goes out (A8) and flickers a little until coming back on for good. Also,  I noticed is that in this flicker state I can turn on the LED slowly like a dimmer switch as I turn up the volume, then after 30 seconds or so it just stays on like normal.

Could this be the tube warming up slowly or dying  on one side?

Thank you

 

[Paul Birkeland]

Does the amp perform normally after it warms up?

If so, I'd leave the amp alone.

It's most likely some odd behavior out of the 12AU7 if everything else is normal.