Ampeg SVT5 Pro - Noisy until warmed up

[SpectorNS2]

Hello, hoping to get some direction if this is a worth while repair or is it new amp time.
Symptoms..
Turn on without guitar connected, it is quiet. As soon as I plug a cable into the input (no guitar) it starts making a loud consistent cracking. If I switch to dirty channel (2 channel amp), there is no noise and amp sounds great but the 2nd channel is meant for grit..so, I want the other channel for most music.
After some time, maybe 10min, it is quiet and sound as it always does.

I figure the PCB board warms up and the connection is remade as the metal swells with heat.
Other than that, I am at a loss for amps.
A guy used it as part of a back line a few moths back. He pinned the input not realizing there was a master volume and ran for 20 min with the O/L circuit light on consistently. I know it has not been the same since.
Taking to a local repair place this week. Hoping for good news but think the input is on the way out thanks to me being kind and letting others use my amp, never again!

 

[Dadum]

Check all the pots. Turn them back and forth many times. It doesn’t make sense that warming up helps but it doesn’t cost anything to check. Put a cable between send and return and see if there is a difference. There shouldn’t be but why not check. Use a different power outlet in your house.

 

[Geri O]

I'm fairly sure that pinning the input wouldn't cause the symptoms you are hearing. Good move on taking the amp to a repair facility, hopefully they are qualified and equipped to diagnose and repair the amp.
I doubt the backline use caused the issue. But yes, that was a kind gesture on your part to provide the amp, especially if you weren't being paid for it. I'll let others use my Mesa rig on shows, it's always opening groups and I let it be known that they are welcome to use the amp to save room and changeover time. but I WILL NOT send my bass rig on an event that I'm not a part of.

Once, on a 6-band festival, we were next to last. The headliner used their SVT810 rig, no surprise there, but they wouldn't allow anyone else to use it. Don't blame them, I was quite happy to use my Mesa rig. One they saw I was willing to let the other bands use it, the promoter handed me a couple of $100 bills without me even asking!
So it does pay to be flexible, but of course, you know your situations and your amp. Definitely need to use discernment in such cases.

 

[agedhorse]

It could be any number of things, probably unrelated to how it was being used.

If the tech is qualified and experienced, they should have no problem troubleshooting and identifying the cause.

 

[SpectorNS2]

Thanks guys, I will post the findings when I get answers.