AmpTalk.com

[elroywagginz]

Hi all, I'm new to the forums.
Any way, was hoping you could help me out with something.
I have a 100 watt Marshall Jcm 900 amplifier head, with 300w quad box of the same brand.
Recently, whilst playing, the volume will suddenly drop to about 50% of it's current setting (approximately, as estimated through the naked ear).
This will happen regardless of whether I have any effects pedals hooked up.
I'm pretty sure the guitar is fine, it works in other amps etc.
Does anyone have any ideas as to the cause, the local tech guys charge like a wounded bull, so self diagnosis is preferable, with whatever help I can get. That's where you come in!! Any ideas?
Thanx in advance.

[elroywagginz]

I just realised I posted this under American amps, oops, like I said, I'm new to forums, forgive me!

[Herb]

How old are your tubes? That's the first place I'd check.
_________________
Yer guitar pickin' friend,
Herb
"It don't mean a thing if it ain't got that swing!"
Doghouse Jazz

[mccorp]

Elroy: Before you try anything else, and the tubes is a good place to check too, I would clean the input jack and the send and receive jacks in the back of your JCM900. Dirty jacks can shut this head down and with symptoms that seem catastrophic when they are not.

[MikeM]

+1 on cleaning the jacks!

[elroywagginz]

Hey thanks guys,
the local tech dude said if it was the valves it would just blow a fuse (rather than do what it's doing), is that correct?
I don't know whether to trust those guys, mainly cos I don't know what I'm talking about when it comes to amps, they do, and it feels like they're trying to coerce me into spending my hard earned dosh (they charge $110 an hour).
Anyway, I will definitely try cleaning the jacks and let you know how it goes, thanks again!