Marshall sv20 5 watt setting not working

[Revcaster]

Hi, after playing live for 35 years i have finally gone back to a Marshall! The sv20 in my opinion is a great amp, like Marshalls of old. Im just wondering if anyone has had this problem, as the 5 watt mode is not working(no sound) and its not a biggie' as i would only use the 20 mode live, but never the less, it should work. Cheers

 

[scozz]

I’m surprised no one has come by yet, maybe this bump will spark something.

Have you posted in “The Workbench”? If not you should, you’ll certainly get a response there.

 

[purpleplexi]

Power tube. Bet you.

 

[JohnH]

It wouldn't seem to be a tube if 20W mode is OK. I'd be a bit careful though, without knowing the cause, in case the no sound in 5W is some connection or switch issue that means there's no load on the amp output, which is a bad thing.

 

[BlueX]

Do you still got warranty for the amp? If yes, I would claim that to get the problem fixed.

The problem might get worse (depending on cause). Even if you don't use the 5W mode it might effect re-sale value in the future.

 

[Plexi4Ever]

Can be a loose contact on the 5w/stby/20w toggle switch. Alternatively an issue in the powerscaling circuit that provides the selectable B+ voltage to the EL34's. I don't think it will be expensive to fix. Best to have an amp tech to look at it if you're not experienced with amp repair (high voltage inside)

 

[purpleplexi]

Had the same thing in my 40CR. Took it to Marshall as I'm quite near. Without even plugging it in the tech said ' it'll be a tube'. And he was right.
The logic is that the 5 watt setting uses half a tube so if it's partly gone you don't notice in full power mode because it's masked by the rest of the tube (and the others) working. But when you go to 5watt the tube can't deliver so you get nothing. Logical when you think about it. If you swap the power tubes around it will work. Not at it's best but it will work. If it does you know it's a tube. Better yet remove one tube and put a known good one in. If that doesn't fix it swap the good one for the other one.

If that doesn't fix it I'm talking rubbish. Has been known. Incidentally they told me that before they checked the tubes they put in a new switch which didn't fix it but they had some dodgy ones in the 40 CRs so they did it anyway.

 

[JustGaryLee]

just reseat your tubes, if it dont work send it back cause it shouldnt be any issue they are pretty much very new well within warranty specs.I have one been playing it for about a year no issues, hope you get it figured out. Just a heads up the 5w setting is still LAF....there is no bedroom mode with these. I run mine with an attenuator for bedroom level times.

 

[Revcaster]

This is a very loud f...ker, and the 5 watt mode is working now as in my haste to try it out,i didnt realise that it is a 3 position switch!! Really stupid hey? Anyway thanks. BTW, its as loud as a JCM 50 combo that i had in the 80's,and has the same smell

 

[BlueX]

in my haste to try it out,i didnt realise that it is a 3 position switch

Yeah, the middle position of the LOW/HIGH switch doesn't make much noise, if that's what you meant. Glad you sorted out the problem!

 

[JustGaryLee]

poodoo!

 

[Gene Ballzz]

This is a very loud f...ker, and the 5 watt mode is working now as in my haste to try it out,i didnt realise that it is a 3 position switch!! Really stupid hey? Anyway thanks. BTW, its as loud as a JCM 50 combo that i had in the 80's,and has the same smell

D'oh!

Just Teasin' & To The Forum,
Gene

 

[nevermind]

This is a very loud f...ker, and the 5 watt mode is working now as in my haste to try it out,i didnt realise that it is a 3 position switch!! Really stupid hey? Anyway thanks. BTW, its as loud as a JCM 50 combo that i had in the 80's,and has the same smell

A lesser man would have never posted such a foible! Thank you for letting other SV20 owners know what was up...

For S&Gs, here's mine:

 

[scozz]

Ok, now we all know that @Revcaster is a standup guy who sucks up up when he makes a mistake!

(to all you perverts out there “suck it up” means he takes responsibility,… nothing else you sicko’s)!

Welcome to the forum Revcaster!

 

[purpleplexi]

Yeah I think I might have just slunk off to another forum.....