Fender Vibro Champ XD - strange noise

[stickfisher]

First post here. Looking for some help. I have a Fender Vibro Champ XD that is acting up. After the amp is warm I get this really crazy scratchy static, even with no cable plugged in. It appears out of nowhere, builds in volume, then just goes away. Almost like it's getting dirty power or something. I replaced the 6V6 drive tube and the 12AX7 pre-amp tube. The sound seems to go away when I remove the 12AX7. Below is a video of the sound. Any ideas?

 

[mRtINY]

Probably the load or bias resistor on one of those triodes in the "pre-amp" tube.

It could be from the digital processor too....

 

[stickfisher]

When I remove the tube and plug it back in the sound sometimes goes away. I opened the amp to see if I could find any issues with the socket but would have had to dig deeper than I was prepared to. I checked the components around the socket and saw a row of resistors. Some of them were touching so I separated them. I touched one particular one and got a bit of a shock. (I know, dumb to be touching the inside of an amp when it's on) I would think that touching the ceramic portion of a resistor shouldn't cause a shock, but I don't know. I'm not going to mess with it plugged in anymore.

 

[mRtINY]

Yikes... If you aren't a tech - pay the guy at the shop....


-tINY

 

[telemainiac]

I had the same problem with my Vibro Champ XD. Then all of a sudden it went totally dead. The Line out still works without any noise though. I'm stumped and don't know if its worth fixing... might be a $150 to fix a $100 amp...

 

[RubyRae]

Ya, mine died many years ago. I found the blown resistors but pain to get to...
These are decent little practice amps but built like crap IMO.