jcm 900 problems

[gfxbss]

hey guys,

my buddy has a marshall jcm 900 100w. everything was working fine until this weekend when he had new tubes put in. now the amp is much, much louder(hey says the current 3 was max vol before), and after about 5-10 min of playing he blows the fuse. the fuse is a 4a 125v low-blow.

from my understanding, the jcm 900 100w usually run 4 5881 tubes. i know my buddy mentioned putting el34s in instead. do you guys think this could be the problem?

thanks guys,

Tyler

[newey]

Some of the Marshall jcm 900 50 watt versions came with EL34s instead of 5881s. But that's 2 tubes, not 4 as in the 100 watt versions. And the manufacturer may have made other alterations to allow the use of the EL34s.

I don't know enough about the differences between these types of tubes to tell you if that's the problem. If your buddy still has the 5881s, in working condition, he should try sticking those back in and seeing if it fixes the fuse problem. If it does, that's a pretty good indication that the EL34s aren't compatible. If the problem persists even with the 5881s, then something else has gone kerfooey and it's time for an amp tech to take a look.

[gfxbss]

thats exactly what i told him to do.... but the fuses arent easy to come by here..... cant find em at hardware stores or radio shack. the only place that did have them was a local guitar repair shop, and they only had the one that blew the last time.....

sooo...... ill let you know when he gets the fuses ordered and we can test it....

thanks newey!

Tyler