Ampeg SVT Classic USA

[umanuman]

I cant figure it out. This head does 3 or 4 gigs or practices, then I plug in and can only hear a faint sound of the bass guitar coming through the speakers. I can shut it down and sometimes it comes back to life. Sometimes it takes a day. I took it to my Tech, he replaced a couple pre amp tubes and beefed up the soldering on the input jacks, but the problem still exists. Going to a gig I never know if its going to fire up or if I have to borrow someone Else's rig. It sucks. Anyone else come across this?

[staindbass]

wiggle the tubes slightly while playing. if there is poor contact on one of the pins, you will hear it come in and out. get your preamp tubes back because they were not the problem.... ask why did he replace them if they were good?

[umanuman]

Thanks, I am assuming you mean wiggle the power tubes. There must be a contact issue with either the pins or the sockets?

Thanks Again

[anderbass]

Do you have any type of standby indicator light? (does it stay red when the amp is malfunctioning?)

[umanuman]

Yes, but I am pretty sure it goes green and I still have the problem. I will double check that when I get back to the studio.

Thanks so much

[username1]

You might want to check the ground wire in the preamp where it bolts to the preamp chassis. I know some had problems with a weak connection there and i beefed up the one on mine to make sure it had good contact by using a bigger washer.

[CntrlScrtnizr]

Originally Posted by username1

You might want to check the ground wire in the preamp where it bolts to the preamp chassis. I know some had problems with a weak connection there and i beefed up the one on mine to make sure it had good contact by using a bigger washer.

OT - love the avatar

Are you the one getting the headlock applied by Randy?

[rickdog]

Another really simple thing to check is the "Power Amp In" jack. It has a switch in it so that when you plug something in there it disconnects the preamp (useful for slaving several SVTs to a single preamp).

Next time your amp acts up like this, just connect a short patch cord or ordinary guitar cord from the "Preamp Out" to the "Power Amp In" and see if that fixes it. Just inserting and removing the cable in the jack may clean it up temporarily; spraying some contact cleaner in the jack might help too.

[Alex1984]

Did you check everything outside the amp? Cable, battery, speakers.

[username1]

Originally Posted by CntrlScrtnizr

OT - love the avatar

Are you the one getting the headlock applied by Randy?

Thanks, yes Randy had me in a headlock lol, didnt think anyone on here would recognize the trailer park boys.
I thought the suggestion of the power amp in jack was also a good one. Best to check the simple things first.

[umanuman]

Rickdog

You were right on the money with the power amp in being tripped. Plugged in a cord and pulled it out and Bam! Back to normal. Can't thank you enough.

[rickdog]

Can't take credit - just passing on advice I've read here!