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  #1  
Old 06-09-2011, 08:48 AM
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Join Date: Jun 2011
Ampeg SVT Classic USA

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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?
  #2  
Old 06-09-2011, 09:09 AM
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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?
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Old 06-09-2011, 09:32 AM
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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
  #4  
Old 06-09-2011, 09:39 AM
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Location: Phoenix. Az.
Do you have any type of standby indicator light? (does it stay red when the amp is malfunctioning?)
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  #5  
Old 06-09-2011, 09:53 AM
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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
  #6  
Old 06-09-2011, 12:26 PM
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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.
  #7  
Old 06-09-2011, 12:32 PM
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Quote:
Originally Posted by username1 View Post
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?
  #8  
Old 06-09-2011, 01:06 PM
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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.
  #9  
Old 06-09-2011, 02:28 PM
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Did you check everything outside the amp? Cable, battery, speakers.
  #10  
Old 06-09-2011, 05:29 PM
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Quote:
Originally Posted by CntrlScrtnizr View Post
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.

Last edited by username1 : 06-09-2011 at 05:37 PM.
  #11  
Old 06-09-2011, 08:15 PM
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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.
  #12  
Old 06-09-2011, 08:22 PM
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Can't take credit - just passing on advice I've read here!
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