5e3 'normal' channel stopped working.

[Jonny toetags]

When I last tested the amp after the build, both channels were working perfectly.
Fast forward a few weeks, we bring the amp to practice to give it a good run-through and the normal channel is dead.
I tried different tubes, but nothing changes.
When plugged into the normal ch, no volume, no sound.
When plugged into the bright channel, and moving the normal ch vol knob, you can hear a bit of bass coming in.

The only thing i know is that my cab making buddy and he had it on for about half a day to burn in some more.

[Bruce / Mission Amps]

When I last tested the amp after the build, both channels were working perfectly.
Fast forward a few weeks, we bring the amp to practice to give it a good run-through and the normal channel is dead.
I tried different tubes, but nothing changes.
When plugged into the normal ch, no volume, no sound.
When plugged into the bright channel, and moving the normal ch vol knob, you can hear a bit of bass coming in.

The only thing i know is that my cab making buddy and he had it on for about half a day to burn in some more.

If you hear bass response coming through the dead channel.... it is working.
the signal is leaking in through the cathode of the normal channel's triode... called cathode driving.

That means your problem is at:
the grid of the normal channel's tube,
it's 68K resistors
or the input jacks are shorted to ground because the shorting blade has collapsed and not opening all the way with a cord plugged int... etc etc.

[Jonny toetags]

Well I finally got a chance to site down and triple check. Bass AND volume come through when on the bright channel and increasing the normal channel volume.
I looked for signs of something burnt or bad solder joints around the the 68K resistors but there is nothing.
What would be the best way to troubleshoot?

[Randall]

The first thing I would do is set my DMM for volts and probe pins 2 and 7 of the first tube. They should both make the same popping sound, and produce the same type of audio noise with you probe on the pin. If one side does not, bad tube or pin connection. If they both are the same, work backwards. probe the other ends of the wires, where the two sets of 68K resistors connect together. Same applies, both should be the same. If not, bad wire connection. If they do, touch a screw driver to the other end of each 68KR. If they all react the same, do the same at the other end of those four wires. If those four points react the same, the problem is with one of the input jacks.