Wierd problem with my hybrid amp...

[Cory_Dylan]

I've had this 50 watt Marshall AVT for almost 2 years not... and i've been having a really wierd problem with it.

Sometimes on the clean channel, it fades over to the overdrive channel back and forth... you can probably imagine how annoying that is. Everything fades over... the green light fades out and the red light lights up. My first guess was a short in the footswitch or something, because if you hit it hard and hit it hard again to switch back, that usually fixes it for awhile. To find out, when it started happening once, I unplugged the footswitch, and it was still doing it.

My guess is that since the lights switch as well, it has to be something in the channel switching.

But I have no Idea.

So, anybody have an idea of what the deal is?

[Kent S.]

Re: Wierd problem with my hybrid amp...

First off ...NO problem is solved by hitting something harder ... that's creates more problems down the line. Second,yeah it sounds like it's in the switching logic, you may have some Fets that are dirfting over due to some leaking caps, then leaking back over again. This would account for it changing states. Does it do it if no footswitch is hooked up at all (as in from the point of power up)? and does it do it randomly, or after it's been on a while and the components have gotten warmer? Either way, the smart thing to do is to put it in the shop, and have a tech look at it. I'm not even sure how the switching is done on those, I woulds imagine being a hybrid it's Fets and not relays. Fets can create that almost fade from one state to another. If you can't find anything wrong with a visual inspection, then shop time is the answer, since the channels are actually changing on you.

[Cory_Dylan]

Re: Wierd problem with my hybrid amp...

Hey Kent,

It does do this randomly. Sometimes it starts doing it after it's been on awhile and sometimes it does it right when i turn it on...

I don't want to take it to a shop because im going to sell this amp pretty soon for 300, and i don't really want to spend money on it. I also don't want to sell someone an amp with a problem. I have a 5 year warranty, but I have no idea where to take it. How much do you think I would have to knock off the amp? It's about 530 new. I only have this problem about 30 percent of the time...

[lastwinj]

Re: Wierd problem with my hybrid amp...

have it fixed, isnt worth jack at th emoment with the problem. and you wouldnt sell it not working propoerly would you? its the FET's in the switching logic or leaky capos in the logic.

germ

[Cory_Dylan]

Re: Wierd problem with my hybrid amp...

What's a FET?? does it stand for something?

[Kent S.]

Re: Wierd problem with my hybrid amp...

What's a FET?? does it stand for something?

Field Effect Transitor, it's not a junction type transistor like a npn or pnp, although thy come in p-channel, and n-channel, n is more commonly used.
Non of that matters though, just that they are a *type* of transistor, and work well for switching. It's not something you are going to troubleshoot yourself. also, I wouldn't knock off any in selling it, I'm mean if someone is willing to go for it, and they know up front what the deal is fine ...That's their call to make. You say it's under warranty, then why would you have to spend any money on it? Most warranties aren't transferrable to new owner's, at least without paperwork ... look on your warranty card/paperwork and call the number, find out where the local serivce center is, get a RA number, and send it off. More than likely you'll have to pay shipping to the center, but those are the breaks. Otherwise, it'd going to be a bit hard to sell. Korg is marshalls distributor in the US, so I'm sure they have more than a few authorized service centers. a quick call or on-line search to the websites of marshall or korg should hook you up.