- Dec 13, 2007
- Reaction score
Older Marshalls are a dream to work on. AND they sound great.
I honestly haven't played a S.J.
But, I do own an early 84 2204 (I say early because it has vertical input jacks. 84 they switched over to horizontal) I learned all that good stuff here
I love the damn thing.
But, it is soooooooooo LOUD
Having board-mounted pots is ok (chassis-mount would be easier for service/replacement), since pots don't make heat.
Yeah. The lessor evil then the two others. Pots are pretty stable beasts and usually clean up pretty well.
The switch to on board pots came as soon as you saw horizontally mounted jacks on 86 JCM's They are mounted that way because they are on the board (and of course it's cheaper for the machine to make) My Studio 15 has this too. Thank god the tubes are chassis mounted. Otherwise I would not own the amp.
That said, because the input jack was board mounted it was nearly impossible to find a replacement for it. Hence another problem when part supplies dry up with these older amps.. Board mounted stuff requires exact replacements while chassis mounted stuff does not..
But the big picture is with the JMP/JCM you are left with an amp that is very simple and easy to service.. Hence a life long friend that needs no replacement.
Reissue amplifiers, along with most any post 2006 constructed electronics device is constructed using lead-free (RoHS) solder. This stuff is good for nothing! It has zero pliability, excessive reaction to temperature changes, poor adhering properties, requires excessive heat to flow (which damages components), and it is unstable.
I was talking with the former head of TC Electronic Service Denmark who was repairing a TC1210 Chorus about issues concerning lead-free (RoHS) solder. He said to me; "Once the solder material becomes unstable, there is no stopping the process. New surface sealers (conformal coatings) have helped mitigate the process, but is a temporary solution at best. Expect an 8 to 10 year life span out of most RoHS constructed products, maybe more, often less..."
I did some research, and discovered that back when solder was first being developed, lead was added for the specific purpose of stabilizing the material. They call this destabilization process "tin whiskers". It's an interesting read...
Hard-Won Knowledge Mitigates Effects Of Tin Whiskers | Components content from Electronic Design
The reason for banning the use of lead solder in the UK was purely political. The compounds used to construct a simple alkaline battery are infinitely more toxic to the environment compared to lead solder. America has not banned the use of lead solder yet, but if you want to sell products abroad, you must adhere to the RoHS directive.
Here's the article I was referring to...
You can rebuild a hand-wired amplifier using leaded solder. With PCB designed amplifiers, you are stuck with the lead-free solder. I totally rebuilt my Cornford RK100 using Kester lead solder. The only remaining RoHS solder is on the back of the pots.
I dig the JCM, but I just love the (Tom Scholtz) LED clipping option of the Jubilee! You can turn the LED's off, for valve only clipping.