#1
Right, well i own a jcm 900 and love it, but lately, whilst at band practice and occasional practice at home whilst the volue has been turned up a bit (parents gone out etc) the volume cuts right out, and its not possible to hear anything. if i turn the amp off for about 5 mins then go back to playing its fine but after about 10 mins (sometimes less) the volume drops right down again. i have no idea what could be causing this apart from the valves maybe? or if its just overheating? i really don't know. i am really considering getting a new amp, to replace it as i'm tired of giving it to amp techs etc. can this problem be easily solved or is it worth replacing it?

all help will be greatly appreciated.

Hairball
Quote by TehJermie
you can get that toneblaster stack at the cost of your dignity.

Quote by silhouettica
fine, screw the cheese sandwich if you must...


#2
Def valves, get it checked out quick by a Marshall dealer or a good amp tech.
#3
i had a similar problem, i realised it was the valves, it don't happen anymore now i'm careful when i plug my guitar in because i can't be bothered to go and get it fixed. my dad said it's really easy to fix because it's (either) that the vavles are loose or they're f***ed, but you can replace them easily once you figure how to.
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Vox V847
MXR MC401 Boost
Roger Mayer Octavia
Zvex Fuzz Factory
Maxon OD-9
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Boss Space Echo RE-20
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Boss TU-2
#4
Quote by ezequiel89
i had a similar problem, i realised it was the valves, it don't happen anymore now i'm careful when i plug my guitar in because i can't be bothered to go and get it fixed. my dad said it's really easy to fix because it's (either) that the vavles are loose or they're f***ed, but you can replace them easily once you figure how to.



Its slightly different when you have a valvestate like yourself mate.

Only preamp valves.

Easy and cheap to fix.

Full sets are another ball game
#5
^lol, oh yh i hadn't thought of that, i guess ur gonna have to take it to a marshall dealer or amp tech like davedoom said, it cost a lot less than getting a new amp.
www.myspace.com/fuelfortiredminds

Fender USA Stratocaster
Marshall BluesBreaker

Vox V847
MXR MC401 Boost
Roger Mayer Octavia
Zvex Fuzz Factory
Maxon OD-9
Line 6 Tonecore Verbzilla
Boss Space Echo RE-20
Line 6 DL4
Boss TU-2
#6
in that case can someone direct me to somewhere (preferably UK) where i can get a nice set of E34Ls at a good price?
Quote by TehJermie
you can get that toneblaster stack at the cost of your dignity.

Quote by silhouettica
fine, screw the cheese sandwich if you must...


#7
E.............................................................................................................Bay
#8
MAke sure its your preamp valves. Basically I had the same problem, when it happend I took a peak in the back of the Marshall and SAw the first EL34 not light up

When this happens to you, I would take a peak at them. to make sure the valve is dead, this way you also know witch one.

As for my amp, acutally the socket was loose so a little wiggle and works again. So ya, might awnt to make sure or find the exact dead valve. to save a little $
1981 Marshall JCM800 2203
Mesa Boogie Tripple Rectifier 2 Channel
Avatar G412 4x12 Vintage 30s
Sobbat Drive Breaker 1
#10
I've seen this problem before.

First, replace the valves if you haven't already. Also clean out the sockets. Make sure all pins on valves are straight. maybe SLIGHTLY and GENTLY bend them inward to make better contact. Now take the amp out of the chassis and look underneath. Do you see and burned out resistors (probably not), if you do, they need to be replaced. Now here's an important part. Do you see any "rusty" solder joints (probably). Remelt every solder joint you can get to. The PCB solder joints aren't as important here as they are much harder to get to. SO remelt all solder joints such as on the switches, transformers, caps, valve sockets, wire connections, grounding, etc. Basically all of them you can see. While you have your chassis out, give your pots a thorough cleaning with contact cleaner and silicon. Check your fuse and clean its connections.

so...summary
-new valves
-clean sockets
-look inside for damaged parts
-remelt all accessible solder joints
-clean pots

If this doesn't work, come back here.