AmpTalk.com

[waldo]

Hi,

My Marshall 900 100w 2 ch. Reverb is approx. 10 years old and has already had tube replacement in the past. The current 'Ruby' tubes do not look new and have som ebrown discolouring around the bottom of the glass, but they all glow nice and orangy as they should do. I should change them soon as I play a lot with the amp, and I play very loud - (around 6). I have not had any issues recently except the standby light suddenly stopped working last week and sometimes I have the feeling it is not as loud as it should be... this could be due to the fact that I also play with a Peavey 5150 which is equally loud at 4 or 5...

Last week I played it in the rehearsal room and it was fine - I brought it home with me and I did not touch it all week. Yesterday I went back in the room, set it up, switched in on and waited for a minute, and then flicked the standby switch - BANG! It blew the main 220v fuse. Concerned I unplugged all fx from the loop, checked the loudspeaker cable, turned the volume on both channels down, replaced the fuse, switched in on and after one minute released the standby again - Bang! By the 3rd attempt I gave up.

Got home - did the above again but switched to low 50w mode (two tubes) and selected the clean channel instead of the usual hi-channel. This time it did not blow but a) it made threating lo grumbling sounds (no guitar sound) and ALL red lights were on at the rear.

Please help! Any ideas?

Cheers Brett.

[waldo]

I am answering my own post as it might help others etc...

I just spoke with a techi - it could be at least 20 other things but the fact that the tube warning lights are on and the fuse is blowing indicates that I have a short circuit - probably the tubes can not take the surge up to high power when I release the standby. I need to send the amp to a shop as new tubes needs to be professionally biased anyway.

Not much hope for me eh?

Still, would appreciate any other stories from JCM owners.

Cheers Brett