I have just bought a used Marshall VS65R amp. When I play it sometimes cuts out completely. Sometimes it comes back on by itself, sometimes not. If it cuts out and I plug in headphones, they work. When it goes out if I bang on it around the speaker jack it comes on. ??? When it plays it sounds great. I replaced the pre-amp tube and that made it cut out more. Need help.
Very carefully tap the side of the valve with the amplifier switched "ON" and see if a crackling distorted noise happens. If so the valve is loose or the amp has been dropped and the valve is on the way out
Make sure that when the audio from the speaker cuts, the headphones are still working (try it several times). If this is correct the problem isn't at the preamp or driver tubes. Try to locate the wire that is connecting the speaker with the amplifier. There must be a bad connection at this cable or at the speaker's coil itself. Try hiting with a solid tool (the back of a screwdriver for example) the parts and the connections (not the tubes, just the mountings) while the amplifier is working in order to locate a loosing contact. Once you find it use a soldering gun to fix the connection.
In case of a problem or clarification, don't hesitate to post.
Thanks and regards
Please kindly rate this solution
Stelios
direct FixYa link: http://www.fixya.com/users/technical114
I have owned one of these amps for many years, what happens is the two circuit boards tend to vibrate during use. If you examine closely the solder joints around the larger electronic componets (i.e. big caps) you'll notice broken solder joints. Re-solder and away you'll go. I have to do this every 6 months to a year but I only play loudly about twice a week. You'll need to take the circuit boards out of the chassis to get access to the undersides for solder repair.
×
882 views
Usually answered in minutes!
×