No audio in right channel of mainline [resolved]

[jbishai]

Hey there,

I'd previously assembled my Mainline, and all was right with the world. Recently though, the audio has cut out in one channel of my headphones (they work with not the mainline, and other headphones have the same problem). I think some component has come loose and I need to do a resoldering job, but I've lost the manual so I don't have the resistance/voltage checks anymore. Any advice?

Thanks,
Jason

[Paul Birkeland]

Get in touch with replacementparts(at)bottlehead(dot)com regarding the manual.  You would have to start with a voltage check to do any meaningful debugging.

[amirhosein]

In my experience it the problem is either with the attenuators or one of the switches. What I did to fix this was to use a plastic rod or something, I use a plastic screw driver mount without the head, to poke the solder points to see if I hear any change with headphones plugged in and music playing to see if anything is loose, anything loose would change the sound if poked a bit. You can pinpoint the problem that way and just reheat the joint or add solder to fix it. Should go without saying that you are probably are working with high voltages and should be really careful.

Edit: Check the output transformer connections too, if the audio is completely out this is probably the problem.

[Paul Birkeland]

In my experience it the problem is either with the attenuators or one of the switches.

The place to start is with a voltage check.  If the attenuators are not the problem, you may make them into a new problem by trying to fix them. 

An easy way to test the attenuators is to use a clip lead to temporarily join the outputs of the coarse attenuator to see if that changes anything.

[jbishai]

Okay so what the issue ultimately wound up being was that one of the nuts holding the terminals on the right side had come off. This lead to the regulator throwing strange voltages for the Breg and Kreg on the B side. I scavenged a free nut and washer and blammo back in business. Didn't have to break out the soldering iron after all.