maiden666

Hi i have a jcm900 4500 model,i have had it about 2 weeks and yesterday it started to cut out on both channels,any idea what prob could be,this is my first post so HELLO to you all

Adwex

I have a 4500 also, could be a handful of things, dirty pot, bad tube, blown resistor or diode...tough to say.

First thing I would do is turn all the knobs, see if they're "scratchy".

Next I would use a cable plug with contact cleaner on it plug it in and out of every jack on the amp...maybe a dirty jack contact is causing the cut-out.

Next I would swap tubes around, see if that helps.

__________________
Band Websites:
www.loudrocker.com/
www.myspace.com/rockerlivemusic

5er driver

I had that symptom on my SL-X. The cause was a dirty effect return jack. Needless to say, I then cleaned all the jack inputs on the front and the back, the speaker outputs as well. I douched each one with a good shot of pot cleaner/lube and then rammed a guitar plug in & out about 20 times.

__________________
The 5er Driver

maiden666

the prob was dry solder joints on the circuit board.

marks

I am a new member so hi to all,
I have a JCM900 4100 Dual reverb model, that i bought in about 1987, and a couple of years ago the overdrive went really weak and ponsy. I changed valves Pre amp and power to no avail. The amp has been to Marshall UK for a seperate power issue, where i highlighted the weak distortion only for it to come back working again but still weak.They too changed all the valves as i was incorrectly sent the wrong spec valves the first time! Can anyone help me get my great big ballsy overdrive sound back?. I have been using a Korg pedalboard instead and really miss that sound. Any ideas appreciated.