I have Fender Hot Rod Deluxe and Blues Deluxe amps.After the amps are in use for 20-30 minutes, volume just flat out fades to almost nothing. I have had it checked out and technician could not reproduce the problem, however, he said it was a known issue with these amps. Tubes are OK. What gives?
Music - Fender - Hot Rod Deluxe Guitar Combo Amplifier
Answers & Comments
I want you to do a test. while using the amp plug a pair of headphones into the preamp out... note you will only hear stuff on one side if they are stereo phones and the sound may be fairly weak... while the unit is operating correctely then unplug phones and use it. When it fades out plug in phones compare the level when it was OK... If the preamp output fades lower as well, then we know problem is in the preamp section...
We can do a lot of troubleshooting without opening the amp.
I see nothing in the scheamtics that should be an issue causing this...
Since it didn't fail for the tech, think "what was different?". Are you connecting something else? Foot pedal? Temperature? :Loudness of playing?
Now what else is in common to these two units... AHA! The guitar...
If your guitar has a battery in it, the 20 to 30 minutes fading would correspond to a battery failing and then recovering after you unplug the guitar for a while.