Class 5 issue

[dexter74]

Happy New Year,

I own a new Class 5/C5-01 which I have had for about two months. My issue is, I have noticed that after about an hour and a half or so of playing it the last couple times, the sound fades in and out, like the amp is cutting out or losing power. It has happened only once each session and after a few moments the sound comes back and all is well. I have checked the obvious pedal connections, cables, etc. and they are fine. This phenomena has happened with both guitars I use and was wondering if anyone has a clue what may be the culprit. Sound is great otherwise and I really like the amp.

Appreciate any help/advice.

 

[esquire]

Bad tube?

 

[dexter74]

Which tube would be the likely suspect? Could it also be a loose tube?

 

[rjtm]

It could be a bad tube (most likely a power tube), loose tube, or dirty tube sockets. If its a bad tube, replace the tubes and bias them. If its a loose tube, retension the tube sockets. If it is dirty tube sockets, use electric contact cleaner on an old tube and rub the tube in and out of the socket to clean them. I'd say try cleaning the sockets first, then if that doesn't work, replace your tubes, then if that doesn't work, retension the tube sockets. If none of these work, you should get it checked by a tech

 

[dexter74]

Thank you for the info. One thing I noticed is that grill that covers the tubes is impossible to remove with a standard Phillips head screwdriver. Does removing the cover grill require some special tool? I don't want to strip the screw heads.

 

[dexter74]

Anyone know if there are any Marshall service centers in Northern Calif?

 

[rjtm]

Thank you for the info. One thing I noticed is that grill that covers the tubes is impossible to remove with a standard Phillips head screwdriver. Does removing the cover grill require some special tool? I don't want to strip the screw heads.

Anyone know if there are any Marshall service centers in Northern Calif?

I think you should go from the back, but it is a combo which I am not too familiar with so someone correct me if I am wrong. I think you should just get it checked out by a tech if you are not experienced with working with amps. Any tech could do that job, but if you are looking for warrantee service, I am sure there are tons of Marshall certified techs in your area.

 

[Stringjunkie]

I use a screwdriver on mine with no issues, use a longer one.

 

[Axis]

Sounds like the power tube.
Same thing happened to mine.Replaced it with a reissue Mullard
Sounds fantastic now.
Check the a touch of Class Class 5 owners welcome thread there are pix/instructions
on how to take it apart.Gotta take the back off not the front.
Good luck!

PS If you don't know what you are doing take it to a tech
lethal voltages inside.

 

[DSL100 Dude]

WOAH!!! TIME OUT!!!!!

First off welcome to the forum.

Now back to the C5. YOU CAN ALMOST CERTAINLY FIX THIS ISSUE ON YOUR OWN.

The C5 is designed so that you DO NOT need to bias the amp. It would seem that you have a tube related issue so my recommendation would be to purchase two 12AX7's and one EL84 and swap 'em out. You could of course do one at a time starting with the EL84.

You should be able to access the tubes from the back with no issues. The new model placed all the tubes below the chassis so you don't need to take out the whole thing to work on it. If your standard phillips screwdriver is not getting it done, pick up a set of JIS point and you will be good to go.

 

[dexter74]

Thanks to all for the info. Is there a particular set of tubes that anyone recommends as a replacement? Or specifically, what would be a good compatible power tube (other than a Mullard) to use if that is all that needs replacing? I play a Les Paul with PAF pickups and a Strat sometimes. Prefer the early Clapton (Cream), Page, Beck sounds as far as trying to achieve a good tone is concerned. I currently use an '82 Rat as my overdrive pedal, with a Boss SD-1 as a secondary option. Appreciate all the knowledge out there.

 

[DirtySteve]

What DSL100 said! That metal grill should come off pretty easily, I've removed mine so many times swapping tubes it's not even funny, and I have one of the 1st run C5s with the tubes up inside. I like Mullard ri or TungSol (or one of each) for preamp tubes, JJ or TAD power tube...my 2 cent's. (personally I don't care for JJ preamp tubes but some do)

...and welcome to the forum!

 

[DSL100 Dude]

The awesome thing about the C5 is that you should be able to pick up a few single EL84's on the cheap since they don't need to be matched.

 

[Axis]

OOPS !
The new CS-01 you can get to the tubes from the back.
Wish I had a dollar for everytime I took my C5 apart(haha)

 

[DirtySteve]

OOPS !
The new CS-01 you can get to the tubes from the back.
Wish I had a dollar for everytime I took my C5 apart(haha)

Yeah me, too!!...I finally just left the metal grill off and removed the small back piece at the bottom so I can just reach up in there and feel for it. I like the way it sounds open like that, but it's been so long I can't remember why. haha