Ampeg SVT4-Pro Problem

[SVTDOUBLEBUCK]

Alright so I purchased this ampeg svt-4pro, I bought it knowing it had problems, so I was told that the head sometimes "clips" when turned on, and stays like that........the power amp works great, its just the preamp that stays clipped. I searched the forums and they all gave me a runaround, and I wanted to ask fellow tb'ers before I brought it to a repair guy....could it be the preamp tubes? the ohm load is fine, so its not my cabs......any suggestions?

 

[Dino@Ampeg]

When you say it stays "clipped", are you referring to the red MUTE/GAIN LED? If this is the case, what's happening is that the MUTE function is engaging itself. Usually this can be fixed by cleaning out the MUTE jack on the back of the amp. Sometimes the connections get oxidized in there and need to be loosened up. Plugging a 1/4" jack in there and sliding it in and out can clean it out a bit. Contact cleaner can help to.
If that doesn't help it could also be in the MUTE button on the front too. I've seen some 4 PROs where that needed to be either cleaned or replaced as well