JVM205C Volume fades away

[MilosP]

I bought a JVM205C (new approx. 12 months ago). It has worked well on both its Clean and Over Drive channels up until recently. Now after playing for about 15 - 20 minutes continuously the volume seems to fade away (not totally muted but very noticeably - very similar to turning the volume down on the guitar - you lose both volume and tone). Turning the volume up doesn't fix the problem. This only seems to be happening on the CLEAN - Green and CLEAN - Orange settings. The CLEAN-Red and the Overdrive settings appear to be working ok. I'm not a Tech guy so I already know this is something I won't be able to fix if it involves taking the back off the amp. Any suggestions on what might be causing this issue or how it can be fixed would be most appreciated!!

 

[Bo Gan Con Lai]

Hey, I've got a JVM410HJS with a similar problem. Clean channel green and orange (haven't tried the red mode yet).
Crunch and OD1 and OD2 work fine.
The first thing people will say is to check the preamp tubes. The one that provides the gain to the Clean Channel will be the problem. But if it's not that then I don't know ..

 

[MilosP]

Hi Bo. Thanks for your reply and suggested cause of the problem. I'll drag the amp off to the repair shop this week and suggest they have a look at the tube(s) for the Clean Channel gain.