Lee Jackson Metaltronix Amplifiers

[pazman6]

My VL-1002 has a bad 60hz hum. I have looked it over and see nothing that looks bad. Tubes have all been replaced. Any ideas on which caps I should replace or other options. The hum is in the power stage, as I can have all knobs turned down including masters and it still hums. When I engage the Attentuator, the hum is proportional to the setting on the attenuator. The hum does seem to change slightly with master volume setting, with the least hum occuring at 12 oclock, although it is only a very slight decrease. It fried a few preamp tubes when I first got it - actually turned the leads inside the tube blue (like a gun barrel).


It is also very sensitive to any volume pot or switch noise from the guitar - actually extremely sensitive. A dirty pot produces static and pops as loud as the guitar notes. My gain on the dirty channel seem to really be lacking, no matter what tubes I use.

Any ideas on how to tackle these two problems is greatly appreciated. I have pdf versions of the schematics if anyone needs them.

pazman6
(pazman6 at cox.net)

[HERCULEES1]

I have the same problem ... even with the output turned down , and the hum balance pot will not clean it up

Ive even fed the power section from the effects return with a different preamp , its not the preamp its the power amp

I pulled out several of the power supply capacitors when i had the board out of it at the place i work at and checked them with a capacitor checker and they read the correct value , I thought it might be them

Im not sure if it can be fixed I gig with it this way now and it is annoying

sometimes i take the preamp signal out the effects send and run it into my jcm 900

that works ok