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03-18-2011, 03:14 PM
|  | Registered User | | Join Date: Feb 2009 Location: Jamestown, NY | | | Ampeg SVT CL broken: looking for a diagnosis
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Hello! I recently purchased a used broken Ampeg SVT CL on ebay. Seller stated they had no idea what was wrong but that it powered up. They had stated they put new power tubes in and that didn't make any difference. Other than that, the person had no idea what was wrong. I thought the deal was not too bad for it and at the very least I would have either a good amp after some work or a good flipper so I picked it up. When I received it I started to note the condition. Maybe you can help me fix it up. There's no luthier I know of within 2 hours of me so I have yet to want to take it out there to someone...being that I just moved to the edge of the earth (i.e. Lubec, Maine).
-The amp powers up and lights up
-Turning the standby on powers the tubes up
-Every tube lights up
-The fan comes on and is rather surprisingly loud (although, I've never owned an SVT CL before to compare). It just sounds like a regular fan, nothing rattling or extra-curricular
-No sound comes out at all
That's all I've got. Could it be a transformer issue? An issue with the speaker outs? I really don't have much idea myself. Thanks for your help if you have any!
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Originally Posted by two fingers  I imagine playing that thing is like having several girlfriends at once. It probably seemed like fun at first but........ | |
03-18-2011, 03:57 PM
|  | Hey, what does this knob do? | | Join Date: Sep 2008 Location: New Hampshire | | | Plug an instrument cable into the "power amp in" jack, hold the plug at the other end by its BARREL and SLEEVE, and VERY SLOWLY slide your "sleeve fingers" toward the tip, listening for sound. |
03-18-2011, 04:27 PM
| | Registered User | | Join Date: Feb 2009 Location: Jamestown, NY | | | Alright, I tried her and got no sound.
__________________ Quote:
Originally Posted by two fingers I imagine playing that thing is like having several girlfriends at once. It probably seemed like fun at first but........ | |
03-18-2011, 04:29 PM
|  | Registered User | | Join Date: Jan 2010 Location: KY USA | | | Have you checked all of the fuses? The fuse for the heaters and fan is working, but maybe another fuse is out. I can't remember if an SVT has two or three fuses, probably two.
The output transformer could be blown.
There could be a fried resistor in the output section.
There may be a loose solder joint particularly in the power section.
You should give the output jacks and tube sockets a good cleaning with De-oxit, but I don't expect that to solve the problem by itself.
Last edited by AwkwardLoudness : 03-18-2011 at 04:32 PM.
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03-18-2011, 04:40 PM
| | Registered User | | Join Date: Feb 2009 Location: Jamestown, NY | | Quote:
Originally Posted by AwkwardLoudness Have you checked all of the fuses? The fuse for the heaters and fan is working, but maybe another fuse is out. I can't remember if an SVT has two or three fuses, probably two.
The output transformer could be blown.
There could be a fried resistor in the output section.
There may be a loose solder joint particularly in the power section.
You should give the output jacks and tube sockets a good cleaning with De-oxit, but I don't expect that to solve the problem by itself. | I just assumed the worst when I purchased it. I have had an Ampeg V4 with a blown fuse before - that one wouldn't even power up the tubes. I'll check to see the fuses on this one.
__________________ Quote:
Originally Posted by two fingers I imagine playing that thing is like having several girlfriends at once. It probably seemed like fun at first but........ | |
03-18-2011, 04:41 PM
| | Registered User | | Join Date: Jan 2010 Location: Vancouver | | | Test the DI out to check the pre-amp. |
03-18-2011, 04:58 PM
| | Registered User | | Join Date: Feb 2010 Location: Nude Zealand | | | Got it! It's fu*ked.
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03-18-2011, 05:07 PM
| | Registered User | | Join Date: Jul 2007 Location: Dallas, TX | | | You don't want a luthier, you want an amp tech. Find one, and bring it in.
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03-18-2011, 05:12 PM
| | | Quote:
Originally Posted by michael_atw Hello! I recently purchased a used broken Ampeg SVT CL on ebay....
at the very least I would have either a good amp after some work or a good flipper so I picked it up.
...
I really don't have much idea myself. Thanks for your help if you have any! | I love it, you buy a known broken amp, not knowing what it's going to take to fix. No place around to fix it, and you don't have an idea how to work on it.
Brilliant!
So there's a market on broken amps - who would have thought?
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03-18-2011, 05:16 PM
| | Registered User | | Join Date: Feb 2009 Location: Jamestown, NY | | Quote:
Originally Posted by RickenBoogie You don't want a luthier, you want an amp tech. Find one, and bring it in. | Whoops - that's what I meant 
__________________ Quote:
Originally Posted by two fingers I imagine playing that thing is like having several girlfriends at once. It probably seemed like fun at first but........ | |
03-18-2011, 05:18 PM
| | Registered User | | Join Date: Jan 2010 Location: KY USA | | Quote: |
Originally Posted by seamonkey I love it, you buy a known broken amp, not knowing what it's going to take to fix. No place around to fix it, and you don't have an idea how to work on it. | For a low enough price, it could be a good deal that's worth while. Though, it's best to know how to fix amps. I've flipped a few broken amps myself after restoration. Quote: |
Originally Posted by seamonkey So there's a market on broken amps - who would have thought? | A few days ago, I got outbid on a non-working vintage Ampeg B15N. Final sale price was over $1,200. Too much for me to pay for a fixer upper. So, yes, there is a market for broken amps. |
03-18-2011, 05:19 PM
| | Registered User | | Join Date: Feb 2009 Location: Jamestown, NY | | Quote:
Originally Posted by seamonkey I love it, you buy a known broken amp, not knowing what it's going to take to fix. No place around to fix it, and you don't have an idea how to work on it.
Brilliant!
So there's a market on broken amps - who would have thought? | Nice sarcasm. Yes, there are markets for broken amps. Especially SVT CL's with whole new sets of tubes. Like I said, I assumed the worst. You don't even know what I paid for it. I didn't say I COULDN'T find a place to fix it...I merely stated I haven't yet ventured to spend the gas and energy and was looking for info from tb'ers. If you don't have info, move on.
__________________ Quote:
Originally Posted by two fingers I imagine playing that thing is like having several girlfriends at once. It probably seemed like fun at first but........ | |
03-18-2011, 05:28 PM
| | | | It would be a good hobby if you knew and liked to fix amps. Otherwise I don't think anybody but techs have a chance of profiting.
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"The good thing about science is that it’s true whether or not you believe in it." - Neil DeGrasse Tyson 2011
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03-18-2011, 05:35 PM
| | Registered User | | Join Date: Feb 2009 Location: Jamestown, NY | | | I could take it back to my hometown and get it looked over, but that wouldn't be until Easter-time. I know the luthiers and amp tech, I wouldn't have a problem paying them to fix something and wouldn't be charged as much because I know them. I myself have only little passing knowledge about amps - which is clearly why I posted this question on here. Sadly, some people would rather patronize than provide information - but that's nothing new on talkbass. I take no offense because I know how much I can make even if it is a major fix.
__________________ Quote:
Originally Posted by two fingers I imagine playing that thing is like having several girlfriends at once. It probably seemed like fun at first but........ | |
03-18-2011, 05:36 PM
| | Registered User | | Join Date: Feb 2009 Location: Jamestown, NY | | Quote:
Originally Posted by Alex1984 Test the DI out to check the pre-amp. | Do the same thing with that as I was told to do with the power amp?
__________________ Quote:
Originally Posted by two fingers I imagine playing that thing is like having several girlfriends at once. It probably seemed like fun at first but........ | |
03-18-2011, 05:48 PM
| | Registered User | | Join Date: Nov 2009 Location: South Florida | | you are not the first to buy something they didn't know what was wrong with it. I have a new CL and it cost $1600. Hopefully you didn't pay too much . Pay the bench fee and get the verdict. Maybe you can at least get your money back . Good luck .....  |
03-18-2011, 05:51 PM
| | Registered User | | Join Date: Feb 2009 Location: Jamestown, NY | | Quote:
Originally Posted by waleross you are not the first to buy something they didn't know what was wrong with it. I have a new CL and it cost $1600. Hopefully you didn't pay too much . Pay the bench fee and get the verdict. Maybe you can at least get your money back . Good luck ..... | Thanks.  I had pretty much no doubt I would get my money back. I paid $350 for mine.
__________________ Quote:
Originally Posted by two fingers I imagine playing that thing is like having several girlfriends at once. It probably seemed like fun at first but........ | |
03-18-2011, 08:27 PM
| | Registered User | | Join Date: Nov 2003 Location: St Louis | | Quote:
Originally Posted by michael_atw
-The amp powers up and lights up
-Turning the standby on powers the tubes up
| How do you know that second part? if no sound, how do you know there is any high voltage to the tubes (which is what the standby controls)?
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03-18-2011, 09:24 PM
| | Registered User | | Join Date: Feb 2009 Location: Jamestown, NY | | Quote:
Originally Posted by Jerrold Tiers How do you know that second part? if no sound, how do you know there is any high voltage to the tubes (which is what the standby controls)? | I assumed by their glowing that they were receiving power. Is that incorrect?
__________________ Quote:
Originally Posted by two fingers I imagine playing that thing is like having several girlfriends at once. It probably seemed like fun at first but........ | |
03-18-2011, 09:40 PM
| | Registered User | | Join Date: Jul 2009 Location: Bristol, UK | | | The glow means the heaters are getting power, but the HT (high tension) voltage that powers the plates could be out (that is what the standby switch turns on and off as standard). It is much higher voltage than the heaters.
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