Marshall vs100, hums, no sound from speakers or headphones

[TallmanKen]

I bought a used marshall vs100 headunit for 20 bucks. When I hooked it up all I heard was a hum, from both the speakers and the headphones. I do not hear anything when I hook up my guitar. I took it apart and replaced the tube as suggested by a friend. No change. I noticed from a youtube video of a guy showing his vs100 having sound issues, and I noticed the led2 and led 3 light up when he strummed his guitar. Mine do not at all. I also noticed that the hum corresponds to a electrical buzz emitting from pcb in the back of the unit, the one that has the heatsinks on it.

I did a lot of searching for what might be the issue but I didn't find any one that fit my senerio. This looked like a good place to start if any for posting.

I am really new at this, this is my first amp and I have a silly notion that I can fix this. I am fairly good at trouble shooting and repairing things and I would really like to get this unit working. I have downloaded the schematics for the vs100r and want to know how to start out tracking down and fixing this.

p.s. One of the other things I knowticed about the unit, when I have head phones hooked up, I can hear slight pop when I hit the Power Dimension switch. I don't know if this is important or not.

[Enzo]

See if there is a bunch of DC voltage on the speaker wires when it is turned on.

Also check the main fuilter caps for solder.