What is wrong with my amp, please help!

Hello
Earlier this year i bought a Marshall AFD100 Slash signature amp. It has been working okay untill now. The problem started yeterday when i turned it on, Very little sound came out of the amp, so i tried to shut it off and then back on. But now all the tube failure lights were on (they are indicating failures on the back of the amp). All 4 of them, and no sound is coming out of it. I don't know what has happend. In the manual it say that it might be the HT fuse that has gone when all of the 4 lights are on, at same time. (previously there have been small problems with it, sometimes the sound in it fades away and becomes very quiet, then later to come back up to normal level...) I am very, very happy for the amp and want it repaired at all cost! I still have my warrenty on it so i can get it repaired. But what can cause this?

Please help me guys :)

Sounds like one or more of the tubes is gone... at least if I remember correctly from my Marshall JCM days.

But how the hell can all 4 tubes just go like that from one moment to another?
Can it be something internal too?

I hear ya... I'm just going by my Marshal days which was quite a ways back. When one tube would go, the amp would start doing what you're describing. It sounds like your amp has "this tube is shot" indicators. Mine didn't. Usually when one tube went, it was time to replace them all, though that was more of a practical decision in trying to avoid having tube failure during a gig. Maybe try getting a replacement, switch out the tubes one by one until you find the bad one? Not sure if that's recommended though.

Today im going to change them all to see if it works, if not. im sending it back to Marshall for repair. They just adviced me to change tubes before i send it back due to the tubes only having 6 months of warrenty.
One more Question - How can it be possible that if one tube dies, all the sound in the amp does too? Cause thats what happend. There is absolutly no sound in this amp. Do they affect eachother or how does it work?

If they are wired in series and a tube fails, it makes sense. It's kind of like a circuit in your house. You have several outlets in your house that run on one circuit, if the circuit breaker pops, then everything in that circuit goes dead.

My guess is that this is probably the same type of situation in the way the tube sockets are wired. I'd suggest going and buying one tube of the same type, then replacing each tube one by one to see if you can find the tube that's gone bad.

Also, you might want to head on over to these guys http://www.ax84.com/. It's a fantastic DIY tube amp site. They have extremely knowledgeable folks on their forum.

But it's just that i went to the store yesterday to check the tubes for failures. But nothing was wrong with them. Im getting pretty sure it's something inside the amp. And if there was something wrong with a tube, wouldent there be atleast a little output from the amp. There is NO sound at ALL.

Just a thought... have you tried a different cabinet to rule out any issue with the speakers? I don't know if the amp has a "direct out" (I doubt it) that you could check also.

I have Also checked for that. Nothing is wrong with the cabinet. Now im sending the thing back to Marshall for repair.

Thanks for the help guys!

Good luck on the repair. They will get it all fixed up for you!

Originally Posted by: RickBlackerIf they are wired in series and a tube fails, it makes sense. It's kind of like a circuit in your house. You have several outlets in your house that run on one circuit, if the circuit breaker pops, then everything in that circuit goes dead.

My guess is that this is probably the same type of situation in the way the tube sockets are wired. I'd suggest going and buying one tube of the same type, then replacing each tube one by one to see if you can find the tube that's gone bad.

Also, you might want to head on over to these guys http://www.ax84.com/. It's a fantastic DIY tube amp site. They have extremely knowledgeable folks on their forum.

If they were wired in series I wouldnt have thought it would be worth having an indicator for each valve as I think the post indicated.

Originally Posted by: CrowhueIf they were wired in series I wouldnt have thought it would be worth having an indicator for each valve as I think the post indicated.

You bring up a good point. I must have skimmed over that. Went back and re-read his original post.

I just shipped the amp back to Marshall today. Miss the damn thing already!