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  #1  
Old 08-09-2022, 06:21 PM
FoxHound4690 FoxHound4690 is offline
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Default Tube amp died.....

My tube amp is a Strauss SVT-20R.
The other night i'm jamming away then all of a sudden my amp starts producing alot of static noise, like buzzy kinda static then the sound went faint and then eventually after a minute or so completely died. i'm not too concerned about it because it's under warranty still so best case scenario is I get a brand new amp but just wondering exactly what happened to it??? There was also a bit of a smell coming out of the amp too like something hadburnt out, like a piece of burnt electric wire or something.

The tubes didn't blow because they all went dark at the same time and weren't glowing even with the amp still powered on, the guy at my store checked the fuse really quickly and the fuse was still fine so wasn't that. So what we diagnosed was it was not the tubes, the fuse or the power supply...

Anyone have any idea what it might have been that caused the entire amp to just go dead?
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Old 08-10-2022, 06:34 AM
Rudy4 Rudy4 is offline
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"All the tubes went dark..."

My first guess would be the filament windings in the power transformer cooked. There's not much circuitry between the filament windings and the tube heaters, so that in conjunction with the burnt wiring smell would be the tip off. Normally the tube heaters are powered when the amp is turned on, so "no glow / no go".

Stuff like this happens and isn't necessarily an indication of quality or lack thereof.
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Old 08-10-2022, 01:05 PM
Dru Edwards Dru Edwards is offline
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Any chance you were using an instrument cable rather than a speaker cable and blew the transformer? Or is it a combo amp?
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Old 08-10-2022, 01:24 PM
jay42 jay42 is offline
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Basically, someone...an amp tech...needs to pull all the tubes and check them. If they're good, then open the amp, plug it in and turn it on. Then she or he will start checking voltages and eventually ferret out the problem. I should add that the actual first thing that happens after opening the chassis it to look for any black spots where the smoke got out.
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Old 08-10-2022, 02:05 PM
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Bob Womack Bob Womack is offline
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Be aware that some amplifiers have fuses inside that aren't mentioned in the instruction manual. My little Marshall JTM612 from 1995 finally blew an EL34 power tube in 2018, taking with it a couple of resistors and an internal fuse. It went HUMMMMMM... click. Silence. There was a burning smell as well. The tubes were dark. The EL34 looked like this when I pulled it:



Note the little dimple halfway up from overheating. I've got that one displayed in the control room of the studio where I work. New power tubes, components, and fees came to $124.50 at the best tech in the area. More, HERE.

Bob
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Old 08-10-2022, 07:32 PM
Rudy4 Rudy4 is offline
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Quote:
Originally Posted by jay42 View Post
Basically, someone...an amp tech...needs to pull all the tubes and check them. If they're good, then open the amp, plug it in and turn it on. Then she or he will start checking voltages and eventually ferret out the problem. I should add that the actual first thing that happens after opening the chassis it to look for any black spots where the smoke got out.
Note, "amp tech".

If you aren't schooled in electronics, NEVER open a tube amp and start poking around. There are LETHAL voltages present if the circuit is active, much more so than the standard solid state amp.

Be Forewarned!
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Old 08-19-2022, 08:03 PM
FoxHound4690 FoxHound4690 is offline
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Quote:
Originally Posted by Dru Edwards View Post
Any chance you were using an instrument cable rather than a speaker cable and blew the transformer? Or is it a combo amp?
It's a combo amp Dru
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Old 08-26-2022, 02:13 PM
gmr gmr is offline
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Even if the circuit is of and no AC is there, the capacitive voltages can be deadly too.
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Old 08-29-2022, 03:09 PM
maxtheaxe maxtheaxe is offline
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Quote:
Originally Posted by Rudy4 View Post
Note, "amp tech".

If you aren't schooled in electronics, NEVER open a tube amp and start poking around. There are LETHAL voltages present if the circuit is active, much more so than the standard solid state amp.

Be Forewarned!
Good advice! The capacitors store voltage for a LONG time (even unplugged) and there is a specific procedure to ground/drain them prior to working on amps. If you don't know it...leave it alone.
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