Kustom tube amp not working

[gdamato]

Hello all,

I have a Kustom Defender 112 tube amp which is not working. I've listed some info on the amp and what I've noticed/tried thus far.

Facts -
- The amp has 2-EL34 power tubes and 3-12AX7 tubes (2 preamp, 1 phase inverter)
- When the power switch is turned on...
-The pilot light on the control panel does NOT illuminate
-Both EL34 tubes illuminate and heat up
-I do not hear any noise/hum even when dials are turned

So far I've done the following, in an attempt to fix...
- Replaced the 2-EL34 power tubes
- Replaced the power fuse located below the power plug
- Swapped the power cord

Any ideas on what the problem may be or any logical next steps to try? Any help/guidance would be appreciated!

[thetragichero]

here's your schematic: https://el34world.com/charts/Schematics ... der112.pdf
led appears to be connected to the -28v bias supply
also appears to use both fixed bias and cathode bias for the power tubes. interesting
if you remove the reverb return cable from the reverb pan and and short the rca contact with say your finger, do you hear anything?

[Stevem]

Hi! Don’t take this the wrong way, but I do not think you have the needed troubleshooting skills to really dive into this!

For example there was no need to try a different power cable if the output tubes where lighting up.

In looking at the schematic the pilot lamp is powered off of a separate minus 28 volt supply protected by two 1 amp fuses inside the amp.

I will bet that one of those two fused has blown, but they do not blow for no reason, so either that circuit has a issue, or one of the 12ax7 tubes is bad.

If you choose to troubleshoot the amp by replacing what I think is a blown fuse then I would first remove all of the 12ax7 tubes from the amp and then see if the LED/ pilot lamp comes on and stays on.