NAD Marshall 6100LM

Racerxrated said:
A lot of those 90s amp manufacturers used plastic molex connectors instead of soldering directly . Marshall was one of them. They would get super warm and the plastic would melt. DSLs, 900s including the 30th Ann. Same issue that the Ampeg VL had.
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I was a Marshall dealer for many years, and I can confirm that I had LOTS of DSL’s come back melted moles connectors.
 
Wasn't there also an issue with the original DSL circuit boards becoming conductive, or am I thinking of a different Marshall?
 
Devin said:
Wasn't there also an issue with the original DSL circuit boards becoming conductive, or am I thinking of a different Marshall?
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Yes thats correct. It was the original JCM/DSL composite epoxy boards in the bias circuit would become conductive causing runaway bias drift due to too much heat over time.
Marshall fixed the DSL boards starting in 2005 and after.
You can still buy a revised DSL main board for like $200 bucks.
Not super complex to do.
There are those rare bird JCM-DSL-100's that don't have any issue.
50 watt DSL's didn't really have the same problems as the 100 watt.
Ive lucked out and had a 2006 & 2009.
 
Samhain said:
Yes thats correct. It was the original JCM/DSL composite epoxy boards in the bias circuit would become conductive causing runaway bias drift due to too much heat over time.
Marshall fixed the DSL boards starting in 2005 and after.
You can still buy a revised DSL main board for like $200 bucks.
Not super complex to do.
There are those rare bird JCM-DSL-100's that don't have any issue.
50 watt DSL's didn't really have the same problems as the 100 watt.
Ive lucked out and had a 2006 & 2009.
Click to expand...
I have a 2011 JCM2000 DSL. None of the issues that plagued the earlier batches are an issue with mine.
 
Racerxrated said:
Not without re-working the circuit?
5881-6L6-KT66.
6550-KT88-KT90.
AFAIK
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Had a jcm 900 mkiii 100watt came with el34 and wouldnt bias up cause it really came with 5881`s. Forums fav amp maker at the time told me it would work. I put em in and biased up perfect. Ran it for a few years like that
 
Yeah, those DSLs had the traces for the grids and screens running adjacent/parallel close to the tube socket because the pins are adjacent. Not usually a problem but as the board heated it got conductive and the positive screen voltage pulled the bias voltage less negative and the current would creep up. I changed the board for a friend but the new board still did it just not as bad (I can't verify that I got a board that was "new enough", it was claimed to be). Allegedly this issue gets worse as the board ages. If I had to guess I would think the molten molex connectors are just what happens when it finally melts. That one my friend had got surprisingly hot and tubes glowing cherry and all...but it never died.
 
SpiderWars said:
Yeah, those DSLs had the traces for the grids and screens running adjacent/parallel close to the tube socket because the pins are adjacent. Not usually a problem but as the board heated it got conductive and the positive screen voltage pulled the bias voltage less negative and the current would creep up. I changed the board for a friend but the new board still did it just not as bad (I can't verify that I got a board that was "new enough", it was claimed to be). Allegedly this issue gets worse as the board ages. If I had to guess I would think the molten molex connectors are just what happens when it finally melts. That one my friend had got surprisingly hot and tubes glowing cherry and all...but it never died.
Click to expand...
In my experience alot of melted molex type connectors involve user error like kids using attenuators and/or impedance mismatches. Those DSL's had some grounding issues with the 16 ohm /8 & 4 ohm jacks also.
There is an easy fix for that but again ive never had any problems with these amps at all.
All issues aside the JCM 2000 DSL-100 is an amazing sounding amp right out of the box.
A great platform.
 
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