Jcm2000 dsl100

[lowell]

Hey all,
Amp owner would like to add a footswitch to this amp to control the channel two "mode" switch. He said the footswitch could be run from the reverb jack on the back. Looking at the schem I'm having a hard time decoding marshall's switching diagram with their "con" connectors. Where do these "CON" symbols connect to...?? I think the switching circuit with CON4 is the channel circuit being that it has LEDs. Am I right or is that controlling channel switching and mode switching? Can someone explain where CON4 is connected to and shed some light on this circuitry? I think once I'm shown how these CON symbols are connected I might be able to take it from there.

[bnwitt]

If you look carefully at each schematic you will see that each connector has a note saying where it goes to and what other schematic the other connector is on. For instance, on the schem you posted connectors 3 and 6 go to connectors 6 and 5 on schematic JCM2-60-00. That being said it appears there is a discrepancy in the notes on the connector your reference. The note says that connector 4 on the 61 drawing goes to connector 5 on the 62 drawing. Strangley though the note on connector 5 on the 62 drawing says it goes to connector 2 on the 61 drawing not connector 4. You have the amp, that's the best way to figure it out. trace the footswitch jacks. The circuit section with the LED's is part of the switching circuit as is the section to the right and the section at the top right on that schem.


The thing that gets confusing in the set of schems on this amp is the file names don't always match the drawing numbers on the sheets. Suffice it to say that you ignore the last two numbers. The drawings are 60, 61, 62, 63, and 64

[lowell]

ok thanks for your help. I'll have the guy bring it in so I can get in there and poke around to get my bearings.

[Enzo]

The schemastic refers to sw1 sw2 sw3, etc. The front panel has names for them. Until we see the amp to find out what the hell number switch "mode" might be, it is tough to guess.

[Pedro Vecino]

sw1 is clean/crunch mode.
In clean, 1a redirects R7 to gain pot and 1b close R9 (R2 direct to ground)
In crunch 1a redirects R12/C7 to gain pot, 1b is open (R9 is active) and 1c adds a extra capacitor between gain pot leads

sw3 is lead/lead with boost
in lead, 3b reduces value in gain pot (1M+150K paralleled=130K)
in lead with boost, 3b assign original value in gain pot (1M) and introduces a capacitor between central pin and ground to tame the highs
3a introduces a 1uF cap (C13) in V1b (paralleled to cathode resistor) for lead boost

sw4 is the "shift" procedure.
In off is standard Marshall tone stack: 470pf in treble, 33K slope and 22n in mids
In on: 235pf in treble, 101K slope and 11n in mids

sw5 is active "deep" mode. When close R43, this mode is on.

Sorry for my poor english

[Enzo]

Thanks, that helps. But whwich one is lowell referring to of that list.

Your English is fine.

[Pedro Vecino]

Hello. CON 4 goes to CON 5 in rear PCB (to switching jacks):
http://www.drtube.com/schematics/mar...jcm2-62-02.pdf

I dīont know if I have understood well, but itīs not possible to accede to a selection of the lead modes across footswitch. For it itīs necessary to automate the selector sw3 (three lines) across relays (a lot of work).
Regards