hi guys.
I'm borrowing a Marshall JTM60 combo off someone at the moment, which required some work doing to it. Mainly once the valves warmed up the volume phases in and out.

I've just picked it up this morning from being repaired, apparently it's had a major service (PCBs resoldered, pre amp sockets replaced, output tubes etc.) which i was charged £100 quid for, but the problem is still occuring.

I've uploaded a sample of the amp in action. you can hear it most around 10 seconds in, the volume drops straight out then comes back in.
*EDIT link doesn't work sorry will retry later!

Does anyone know how to rectify this, or had a similar issue with their amp?

thanks for any assistance!
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Last edited by ZiggieSmall5 at Feb 11, 2012,
Sounds like a basic "preamp tube is dying" issue. Just buy a preamp tube and swap it around til you find the bad one.
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sorry for the very late reply guys, the person repairing it i've made take back and fix it!
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