** The Marshall TSL122 JCM2000 Repair/Mods Page **

[Steve A.]

They should have really copped to the problem and replaced them all under warranty, right from the beginning. I think some of the other major manufacturers would have. I guess they don't figure it cost them much in sales, so if such a problem occurs again, it will probably be the same scenario.

Once Marshall learned of the problem I think that they should have extended the warranty on the boards a year or two- maybe even longer. And sent out bulletins to all of their authorized warranty stations telling them to replace the board under warranty if it had exhibited the problems. Once the warranty had expired I think it would have been a good faith measure to sell the new boards at a reasonable price with a minimum markup since they had already presumably made a profit selling the amp in the first place.

The damned MFA's look at the costs of repairing a particular model- "a full recall would wipe out all of the profits we made on sales of those amps!"- while they really need to look at the profits of their full line of amps which would certainly cover the cost of a recall. Not seeing the forest for the trees and all that...

Steve Ahola

[Ronsonic]

Just one more comment on these amps:

When you get one in the shop for any reason, Solder a jumper across the ground pins of the 16 Ohm output jack. Marshall was so afraid that someone would plug into the 16 and 8 Z jacks at the same time, they ran the ground through the normaling contacts of the 16Z jack. Those contacts cannot handle that current and eventually burn up creating an open-load situation.

[kirk5443]

Richie Hall just posted a link to this article over at the Tube Guitar Amp Builders group at Facebook. It seems that negative temp-coefficient resistors were used in the bias circuits for some of these amps causing a runaway bias problem after maybe an hour.

The Marshall TSL122 JCM2000 Repair/Mods Page

Steve Ahola

after servicing about 25 of these i have found that just fixing the bias drift issues does not repair these amps,the board material is so bad when it heats up the hv leaks into everything it can and causes several different issues ,also the components used are cheap and drift as well when they warm up.The bias fix works for a while but prolong use will produce other noticeable problems that are real head scratchers ,hums,buzz'z,popping etc...dont waste time repairing the board just replace it hotroxuk has them in stock still[couldn't find dsl boards though they do the same thing],but i still change the swamp resistors to the standard 5.6k which really helps the tone of these amps