Losing volume?

[nilitara]

Hi all

I have a JCM 900 2100 SL-X 5881 50/100 watt head. Over the last few weeks I’m encountering complete loss of volume whilst playing? Only to return to normal after a minute or so?

Hoping someone can give me some pointers for a possible cause to this.

I did clean all the pots last year using contact cleaning spray as a few were scratchy. Could I possibly have a bad pre amp valve? Can I safely remove these and also clean with contact cleaner.

I believe the head can still hold a charge even when unplugged, what’s a safe way to avoid mishaps? Can I turn on the head without been connected to the cab, so I can see if the tubes are glowing.

A lot of questions I know, any help most appreciated

Nige

 

[Tatzmann]

BR-3 rectifier for preampheaters and accompanying capacitors failing, needs surgery. Based on your questions, you'll need a tech for this.

 

[Tatzmann]

You could patch the effectsloop with an instrumentcable to rule out the switchingjacks, maybe you're lucky, but the rectifier problem is coming around the bend anyways.

This is a fairly known problem on the SL-X, so it shouldn't be too hard to find a competent tech that can sort it out right away.

 

[JSJ900]

My 2100 kept cutting out when I bought it years ago (used) - the 50w / 100w switch was bad.

No problems since then until a few weeks ago. Sound was cutting in an out. One of the cabinet jacks needed some DeoIT and that fixed it this time around.

 

[21fret]

Can I turn on the head without been connected to the cab,

you'll need a tech for this.

indeed.
especially before black and white wires get twisted together.

 

[nilitara]

Hi all

A quick follow up, received my amp back today, thanks for all the help guys for pointing me in the right direction as to what the problem could be.

It was indeed the Bridge rectifier, also new smoothing caps fitted too. Happy with £50 all in.

Nige