svt 4 pro cuts out

doomloop · #1 03-20-2013, 12:31 PM

SVT 4 pro running mono, cables are correct for bridged mono

Plays great for >1 hour and then starts to cut out sound intermittently...comes back and seems fine after 6 or 8 mutes. I Haven't pushed it much after that as it's usually toward the end of rehearsals and it freaks me out a bit.

No lights change, no tonal changes.

I am hoping it'll be a pre tube or something simple...maybe one side is going and I'll test the stereo amps to see if I can re-create it on a side.

Anybody have an idea of what may be going on?

JimmyM · #2 03-20-2013, 01:02 PM

You could clean the effects loop with contact cleaner. Sometimes they get corroded over time, especially if not being used, and it can cause that. Or maybe it's your mute switch that needs cleaned. Other than that and swapping tubes one at a time to find a culprit, it's about all you can do as a non-tech end user, and if that doesn't work, then it's tech time.

doomloop · #3 03-20-2013, 01:06 PM

Thanks Jimmy!

I will clean some contacts and check some tubes...maybe see if it's the eq switch as I think I recall a cut when I was switching that back and forth.

Any chance it's just the temp circuit cutting out as it gets hot? I was thinking of mounting a small fan on the back...

hodgy · #4 03-20-2013, 01:09 PM

Quote:

Originally Posted by doomloop

Thanks Jimmy!

I will clean some contacts and check some tubes...maybe see if it's the eq switch as I think I recall a cut when I was switching that back and forth.

Any chance it's just the temp circuit cutting out as it gets hot? I was thinking of mounting a small fan on the back...

I doubt it's the temp circuit. More likely crappy solder somewhere.

BassmanPaul · #5 03-20-2013, 01:12 PM

What cabinet{s} are you using and what impedance are they???

doomloop · #6 03-20-2013, 01:22 PM

I'm using my svt 4 pro into an Ampeg 810e (4 ohms)...I also run my svt classic into one of the same cabs. I've checked the serials on both my cabs with Ampeg and they are the appropriate wattage and impedance for both amps.

I've checked all my external connections, jacks, cables and have been unsuccessful in repeating the issue on purpose...only after about an hour of playing.

Solder is a possibility...what a goose chase though...I would think solder would be a consistent cutting out rather than after a period of playing but I suppose heat and vibration could be the factor.

I'm gonna try the single stereo amps and take the amp off the cab when I play as well as Jimmy's cleaning/testing suggestions...

JimmyM · #7 03-20-2013, 01:28 PM

Well Hodgy is the expert and I'm not a tech. I just know what I do when I need to troubleshoot an amp. So there's a very good chance he's right.

doomloop · #8 03-20-2013, 01:31 PM

I agree as I've read on TB a lot about the soldering issues on these amps. I had one before that worked flawlessly...this one is great too except for this one new symptom...it had been great for the last 6 months, no issues, but it was not new when I bought it.