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Hi All
A bit of a long story that i wont get involved in at present.
JCM2000 DSL with JCM2-60-00 main board and JCM2-61-00 Control board
From marshall DSL100_Valve_PCB_Issue_1..pdf JCM2-60-00
JCM2-60-02 (2001) valve amp iss7.pdf JCM2-60-02
Question .. How many versions are they of this JCM2-60-00 Board. My board clearly states in the far right hand top corner that it is a JCM2-60-00
But my component ref don't match up
But they do match up with JCM2-60-02
Ie on my board
R71 is a 270R 7watt but the schematic for JCM2-60-00 is 10k
R9 & R6 are 1R 2 watt but the schematic for JCM2-60-00 the same resistors are R54 and R68
So it looks like ive got different version of this board ??? Does anyone had this issue, and have the correct schematic
The Customer said he turned it on and it was very low volume. Gave it to a friend ( not a amp tech ) Who changed the valves and still low sound. I beileve at this point
he started to muck around with the wiring. When i got it. It had no sound. I did put the cables back in the correct places ( I think) Found 100k open on V3
That has got the Full sound back. Found that somebody had changed one of the 22k bias pot for 1k and Both cathode 1R resistors were 0.68R and 0.22R.
I think the wiring is correct now,( used wiring from JCM2-61-00 )?? Just want to confirm.. Its got an odd fault. Sounds distorted and if you up the gain it makes a sort of very fast motorboating sound
Biasing is all good Though the marshall way of checking and my Bias meter ( 36ma per tube )
all tubes swapped out
Im going to check it out later and see whats what and get some Volatge reading on here
any help or assistant would be gratefull.
BBB
A bit of a long story that i wont get involved in at present.
JCM2000 DSL with JCM2-60-00 main board and JCM2-61-00 Control board
From marshall DSL100_Valve_PCB_Issue_1..pdf JCM2-60-00
JCM2-60-02 (2001) valve amp iss7.pdf JCM2-60-02
Question .. How many versions are they of this JCM2-60-00 Board. My board clearly states in the far right hand top corner that it is a JCM2-60-00
But my component ref don't match up
But they do match up with JCM2-60-02
Ie on my board
R71 is a 270R 7watt but the schematic for JCM2-60-00 is 10k
R9 & R6 are 1R 2 watt but the schematic for JCM2-60-00 the same resistors are R54 and R68
So it looks like ive got different version of this board ??? Does anyone had this issue, and have the correct schematic
The Customer said he turned it on and it was very low volume. Gave it to a friend ( not a amp tech ) Who changed the valves and still low sound. I beileve at this point
he started to muck around with the wiring. When i got it. It had no sound. I did put the cables back in the correct places ( I think) Found 100k open on V3
That has got the Full sound back. Found that somebody had changed one of the 22k bias pot for 1k and Both cathode 1R resistors were 0.68R and 0.22R.
I think the wiring is correct now,( used wiring from JCM2-61-00 )?? Just want to confirm.. Its got an odd fault. Sounds distorted and if you up the gain it makes a sort of very fast motorboating sound
Biasing is all good Though the marshall way of checking and my Bias meter ( 36ma per tube )
all tubes swapped out
Im going to check it out later and see whats what and get some Volatge reading on here
any help or assistant would be gratefull.
BBB
.. Whats your thoughts on the mainboard i have?
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