Lost left channel

[hibuckhobby]

After several weeks of working well, the left channel began to delay in coming on, but after
a minute or so, it would come in with a slight pop and work perfectly.  As of today, it only
passes a very low level signal.  I've gone over all of the left channel connects and reflowed
the solder joints.  Occasionally the left side will come in, but distorted.  Where should I start
looking?
TIA,
Bob

 

[Paul Birkeland]

I would start with a voltage check.

 

[hibuckhobby]

Voltages as well as resistances all within ranges specified in manual.
ex:  1. 82v 2. 173v etc.  I changed the 12AU7 in case of a bad
driver, but that made no difference.
Bob

 

[Paul Birkeland]

Can you post some photos of the build?  A channel that pops and drops will absolutely show a voltage problem, as pops come from important connections being intermittent.  Sometimes it's tough to get those connections to act up and to be able to get voltage measurements while that's happening.

 

[hibuckhobby]

Hopefully these will be better than my last efforts.

 

[Paul Birkeland]

The 9 pin and 8 pin tube socket wiring will have the connections that could could cause a channel to drop and pop, as could potentially the headphone jack.  The power supply that's built above the power transformer is common to both channels, so an issue there would cause both channels to drop.

 

[hibuckhobby]

Thank you Paul.  I will investigate those sockets further when it cools down.
I left it one for a couple of hours and the channel came back on.  I suspect
that once I have redone all the joints on those tube sockets, the problem
will be corrected.
Bob

 

[Deluk]

On bh1 has the green wire broken off?