TSL 122 upgrade/repair

[Drewser141]

Aloha,

New poster, longtime marshall lover. I recently blew the PT in my TSL122. I ordered a new one from Paul at Mercury. I thought that as long as I'm in there I should drop in a new OT and choke (also from MM). My question is this: what else should I do while I'm in there. I was very happy with the sound of the amp before it blew so I'm not looking to soup it up anymore than the OT/PT/choke will already do. I just want to head off any potential problems before they happen.

Mahalo for all replies.

Drew
76 Strat
06 Les Paul Supreme
Broken TSL122

 

[trigmachine]

if its pre 2006 you may want to replace one of the boards (i cant remember which one) apparently they're notorious for for going tits up. Mine is getting done just now it has something to do with plate voltage and massive bias drift. Im also getting the fx loop converted from paralell to series

 

[plexifier]

Don't bother with a new OT if you're happy with the current sound. I wouldn't recommend MM for an OT anyway.

 

[Lederstrumpf]

If you have the version 5 mainboard, you might either want to replace it or fix it.
The first option might appeal to you if you live in the UK or have extra cash that needs a new home.

If you want to fix it yourself or give it to your tech, follow the advice of Fred Hullerum. I did.
The Marshall TSL122 TSL100 thermal bias drift repair page

 

[Drewser141]

Not in the UK so the repair yourself option looks attractive. Lots of great info! Mahalos to all. One more question, How can I tell what build my board is? Ser# 2004-05-2953B

 

[Drewser141]

I might have figured it out, could it be version 10 (set of numbers on the top)? and if so how much of this mod is already done? It looks like it has the new type resistors & R66 & R70 are 5k6 already. Maybe this will help the next guy too.

 

[Lederstrumpf]

I might have figured it out, could it be version 10 (set of numbers on the top)? and if so how much of this mod is already done? It looks like it has the new type resistors & R66 & R70 are 5k6 already. Maybe this will help the next guy too.

As far as I know, it was only the batch of version5 mainboards that were made of the wrong material, so your version10 mainboard should not have this issue.
I cannot confirm this, however.

 

[RickyLee]

Most important fix for that amp would be the Ground/negative buss on the speaker out jacks.

Do a search for it here at the Forum. Or someone else here might hopefully chime in with the link.

And as for the expensive Mercury output transformer, if you like the tone with the stock Dagnall OT, you might not think that Mercury is worth the $$. At least that is what I have read about quite a few people's experiences on the web.

Good Luck, and Welcome to the Forum!

 

[Drewser141]

Thanks Rickylee, I saw that one first. I wasn't going to do the OT but got a good deal on the package of PT/OT/Choke and since I'm into overkill...

I'm just thinking about the heat problem that seems to be inherent in the design of packin everything into the TSL122 box. When the PT fried, the front panel was too hot to touch-- it never got this hot before. So, how about adding a fan to suck out the heat? To add to my concern I saw a picture of a badly fried ver. 10 board when the R6 cooked (Laurence Wilkens). Too much heat, bad resistor?? Dunno but I'm tryin to avoid that too. So, to fan or not to fan...

 

[Lucifuge]

Most important fix for that amp would be the Ground/negative buss on the speaker out jacks.

Isn't that mod for the DSL's?

 

[RickyLee]

Isn't that mod for the DSL's?

Yes. It applies to the DSL100/50 amp as well as it has the same rear PCB speaker out circuit.

I have not looked at other models of DSL or TSL, but it might apply to some of those as well.

 

[Lucifuge]

Oh, OK... Guess I should check if my TSL has it as well.... I have read about it, but I figured it was just the DSL's that needed that mod....

 

[scat7s]

my buds tsl60 head has an arrangement like the dsl401.

its contigent on your connection to chassis ground via plastic connectors and nuts. its a cheap out from marshall.

hardline the speaker outs to ground. its just the smart thing to do while your in there.