Anyone get the SC20 loop fix implemented?

[Kutt]

Curious if anyone has actually had the "official" Marshall warranty / tech bulletin fix for the FX loop volume drop on the SC20 implemented.

Please don't turn this into a pissing match thread about "it isn't a problem" or "it stops when you turn it up louder" or "use a boost in the loop" or "I don't use mine and you don't need to either" or "I don't see what the problem is" etc etc etc...

Just straight up would like to know if anyone had the fix done and what the result was. Looked like @fer1991 was going to get his done but then radio silence.


Thanks!

 

[paul-e-mann]

Curious if anyone has actually had the "official" Marshall warranty / tech bulletin fix for the FX loop volume drop on the SC20 implemented.

Please don't turn this into a pissing match thread about "it isn't a problem" or "it stops when you turn it up louder" or "use a boost in the loop" or "I don't use mine and you don't need to either" or "I don't see what the problem is" etc etc etc...

Just straight up would like to know if anyone had the fix done and what the result was. Looked like @fer1991 was going to get his done but then radio silence.


Thanks!

Do you know if I bought one today is the problem fixed?

 

[Kutt]

Do you know if I bought one today is the problem fixed?

I do not know. I bought one brand new factory sealed last summer and it was not fixed, though Marshall claims the overall issue was fixed long before my purchase.

I suspect when they state it's "fixed" they are referring to the fact that there is a Tech Bulletin / official Marshall document on what needs to be done, not that the factory is shipping them as such. Just a guess.

 

[Moony]

though Marshall claims the overall issue was fixed long before my purchase.

Where do they claim that?
Do you have a link?

That would also help to find out when the supposed flaw was fixed.
You can see the production date of your amp at the serial number.

 

[Kutt]

Where do they claim that?
Do you have a link?

That would also help to find out when the supposed flaw was fixed.
You can see the production date of your amp at the serial number.

They claim it right here. I also recently obtained a copy of the Marshall Tech Bulletin and it is dated February of 2019, so they had a remedy in place from the beginning.

 

[Moony]

@Kutt


Thanks a lot for the screenshot!
That's very interesting!

So it would be a smart move to buy amps which are produced after July 2021.

 

[Kutt]

@Kutt


Thanks a lot for the screenshot!
That's very interesting!

So it would be a smart move to buy amps which are produced after July 2021.

Possibly. I am still not convinced that the fix went into production. It may only be a Tech Bulletin that is implemented upon customer request via an authorized tech. The Bulletin I have is dated from early 2019. So they knew what/how to fix it way back then but I have read of no known amps from the factory with that fix in place.

 

[Moony]

So they knew what/how to fix it way back then but I have read of no known amps from the factory with that fix in place.

If there's a real issue with the fx loop I don't think Marshall would continue to keep producing the amps that way.
They would fix it like they did with other models too.
But it also seems that not everyone has a problem with the fx loop so if only a minority really complains about it they probably will not change anything in production.

If I wanted to buy a SC20 I would reach out to Marshall and ask them about it.

 

[fer1991]

Curious if anyone has actually had the "official" Marshall warranty / tech bulletin fix for the FX loop volume drop on the SC20 implemented.

Please don't turn this into a pissing match thread about "it isn't a problem" or "it stops when you turn it up louder" or "use a boost in the loop" or "I don't use mine and you don't need to either" or "I don't see what the problem is" etc etc etc...

Just straight up would like to know if anyone had the fix done and what the result was. Looked like @fer1991 was going to get his done but then radio silence.


Thanks!

Hi, sorry for the delay, I did indeed took the amplifier to the service. Things went south when the service was just horribly. Really poorly job done when they changed three resistors for these values: R36 220k, R38 27k, R103 470k.

The job was so poorly done that I just researched for the original values and reinstalled everything back to original specs. I posted everything in the official thread.

The Official Marshall Studio Classic Thread Sc20

@ fer1991 ,This was my original post and ended up getting a "newer" SC20 head. Still has the same volume drop and pop when MV is set low say around 1-2. However when using an attenuator in this case a Torpedo Captor X and have the attenuation on mid setting then there is no discernible pop or...

www.marshallforum.com

Lately I've been changing speakers, cabs, and remember that I freaked out at that moment and I would like to try the fix again, but... I'm not unsoldering any resistor anymore till this becomes another one experience and with better results.


The R103 it's soldered to the treble potentiometer.. maybe that's why I heard everything more trebly? is necesary to change that resistor that looks away from the fx loop? maybe now I would like the audio change? So many questions and diners ready. Hope this helps

 

[Kutt]

Hi, sorry for the delay, I did indeed took the amplifier to the service. Things went south when the service was just horribly. Really poorly job done when they changed three resistors for these values: R36 220k, R38 27k, R103 470k.

The job was so poorly done that I just researched for the original values and reinstalled everything back to original specs. I posted everything in the official thread.

The Official Marshall Studio Classic Thread Sc20

@ fer1991 ,This was my original post and ended up getting a "newer" SC20 head. Still has the same volume drop and pop when MV is set low say around 1-2. However when using an attenuator in this case a Torpedo Captor X and have the attenuation on mid setting then there is no discernible pop or...

www.marshallforum.com

Lately I've been changing speakers, cabs, and remember that I freaked out at that moment and I would like to try the fix again, but... I'm not unsoldering any resistor anymore till this becomes another one experience and with better results.


The R103 it's soldered to the treble potentiometer.. maybe that's why I heard everything more trebly? is necesary to change that resistor that looks away from the fx loop? maybe now I would like the audio change? So many questions and diners ready. Hope this helps

Very interesting, thanks. The values you posted sound correct. I wonder if the problem was with the poor work by your technician, or if the modifications themselves cause a worse sound quality even if installed professionally. I can't tell from the Service Bulletin if R103 is associated with the treble potentiometer or not:

 

[mark123]

This uncovers a separate but tangentially related issue. Marshall desperately needs to fix their authorized repair network. I've heard more bad experiences than I've heard good. fer1991 and I have had bad experiences with an authorized Marshall repair tech.

The one I used (Tonetronix in Hubbard, Ohio) did not fix the issue and charged me for a warranty repair. I fixed it myself. I would have done it without taking it to them but it was still under warranty. Live and learn.

 

[fer1991]

@Kutt Hey Kutt, thanks for this images, because I thought that at first. I inmediately blamed the quality job, and since they wouldn't show me that information (they shared the values but I just had to trust them) I had my doubts about tryin it again. But, not for me yet. These amps here are really hard to get (you have to get it from another country) and I don't want to screw it up. Please let me know if you try them or know about someone who does.

The R103 it's soldered to the leg of the vr103 (the green pot) and that's the treble pot. R36 and R38 looks close to the fx loop, but I just know how to use a soldering iron, I have no knowloge about circuits.

@mark123 you have it right, I just couldn't believe what they've done. Three resistors, and looked like it was made while beeing drunk.