Volume problem with old Blues Deluxe

The other guitar player in my band has an old Blues Deluxe (4 x 10) and recently had a problem with the volume coming and going towards the end of a gig.

He replaced the power tubes and everything seemed to be fine at band practice on Monday evening - although we weren't playing loud. He left the amp in my music room and suggested that I play through it this week to see whether the problem had been cured.

All seemed well last night. I had the amp going for almost 2 hours and didn't hear anything untoward. But this wasn't at anything like gig levels.

This morning I thought I'd try it again but at louder volumes. After only about 5 minutes or so, the volume suddenly died and then came back again after only a second or so. This happened several times within a very short time. So I switched the amp off.

I had the guitar on 10 and the amp was set pretty loud as well - probably close to gigging volume.

There were no weird noises or crackles when this happened, the volume just died and then came back. Tonally the amp sounds fine.

I phoned my friend and he's going to take the amp into a local repair workshop but I'm curious to hear what might be wrong with it.

Any ideas??

Many possibilities. And...the intermitten, come-n-go quickly aspect makes it hard to diagnose. I first suspect electrolytics when something like this happens. That amp may be of an age where the electrolytics are suspect. PReamp tube?? HEater filament has a cnnection coming and going...I doubt it, but just musing.. BAd connection almost anywhere that affects voltage to the tubes. THe connection thing would very likelyhave a pop! going along with it or a crackling....
The electrolytics keep coming back to mind.
What happens when you slap the fire out of the side or top of the amp?

I didn't try giving the amp a knock or anything. I was more concerned that I didn't cause any more damage to whatever's wrong with it so I just switched it off and left it.

My friend came and picked it up last night and is taking it to a local repair shop today - we need it back for a gig next Thursday!

It could well be something inside the amp that's a bit tired. It's about 11-12 years old and I don't think he's been too interested in getting it regularly serviced over the years other than changing tubes occasionally.

Del, I couldn't help but chuckle. When one of these is acting this way, I am hoping that a good slap/knock/kick will yield a permanence for the flaw. That way, it can be found! LOL I amthinking that this amp is not suffereing from a bad connection, but I could be wrong. LET us know what is found, okay. Learning is.

the volume coming and going towards the end of a gig.

just a guess but it could be the input jack soldering heating up and giving a bad connection.
well, that's whats acting up on my old BDX :rolleyes:

and yes, what Wally said: Many possibilities...