Ive had this issue within the last week, whenver I turn up Master and Lead Master on Channel 1 Lead i get an incredibly high pitched squeal, Ive never had this issue before.
Im guessing its a microphonc tube? I turned off the sound at the speakers, and when I cranked the knbos in question the whistling was actually audible from the preamp out loud, despite it not outputting any sound from the speakers. I did the old tap test with a pencil whilst the amp was on but with no guitar input, but none of the tubes made a sound so Im not 100% certain which tube to replace.
Im guessing I should repace V23 tube from below schematic, as thats for lead 1 which im having issues on?
http://guiguijones.free.fr/Electronique%20&%20Bouine/electronique/Schema%20Amplis%20Effets%20etc/Amplis/Mesa%20Boogie/s-quad5.gif
Im guessing its a microphonc tube? I turned off the sound at the speakers, and when I cranked the knbos in question the whistling was actually audible from the preamp out loud, despite it not outputting any sound from the speakers. I did the old tap test with a pencil whilst the amp was on but with no guitar input, but none of the tubes made a sound so Im not 100% certain which tube to replace.
Im guessing I should repace V23 tube from below schematic, as thats for lead 1 which im having issues on?
http://guiguijones.free.fr/Electronique%20&%20Bouine/electronique/Schema%20Amplis%20Effets%20etc/Amplis/Mesa%20Boogie/s-quad5.gif
