Marshall DSL question

[Valvehead]

I find the Dsl schematic (jcm 2000 ) a bit confusing with all the connectors . Seems the switches are not labeled on the scem either.

Can someone answer this ---

when you switch from OD1 to OD2 , on the dirty channel, ( might be called "lead 1 " etc..) , what exactly is "switched in" to the circuit ? certain caps and resistors ? which ones ?

Id like to know exactly which ones---- I want to play with the OD2 sound

thanks in advance !

scem =

http://www.drtube.com/schematics/mar...61-02-iss1.pdf

[J M Fahey]

In my eyes that type of "schematic" is CRAP, and an absolute lack of respect for technicians.
It is NOT an amplifier schematic by any means, but a printout of the .SCH file used by the PCB design software.
It shows only what is actually on the PCB, not a working amp, nor, much worse, the interconnection between them.
Crazy !!!!!!!!!!!!!!
You will have to print in a *BIG* sheet of paper and pencil draw the actual connections yourself.

[Enzo]

I'll try when I get back to work in the coming week.

Yes, you need to learn to interpret this hodgepodge.

DSL and JCM2000 is not specific. BY your extensions, is this a DSL50?

If you look in the circuitry, you will see various things. There are relays, there are LDRs, there are JFETs. And there are plain old switches. At the various points in the circuit, a relay might select which volume control is active, while a JFET might switch different circuit paths into active states. The LDR might add or delete a resistance from a voltage divider. Any one of those could sweitch cathode bypass caps in and out.

[Gregg]

I find the Dsl schematic (jcm 2000 ) a bit confusing with all the connectors .

That's very mildly said and "crap" is not even close... Woe to you cloners

[Valvehead]

Ha , Im not cloning , just modding ..and when you look at the actual pcb the connectors arent "1 to 1" . As in Con 2 goes to Con 6 and so on..

Enzo, the DSL 50 and 100 are the same preamp I believe , both JCM 2000 model

[Enzo]

I know the similarities, sorry. Just a reminder to all that "JCM2000" doesn't tell us anything. That is about as specific as Chevrolet. The DSL line includes 201, 401, 50, 100, and for all I know maybe more.

SOme prints have noets by connectors. They say CON1 then next to it CN6 2-A4 or whatever, I really should go look. Each page is numbered by board, and each drawing has a letter/number grid for location on the page. The full schematic set on some of these includes a connector chart. It juwst lists connectors on each board, and where it goes.

[diagrammatiks]

are there even any tubes in there?

[J M Fahey]

Not *ON* the PCBs, so they won't care to draw them.
Stupid, isn't it?

[Jazz P Bass]

Actually, that schematic is part 1 of 4.
The tubes are shown on the page where they are located.
Really, what needs to be done by the OP is to sit down with the amp & the schematic & mark what switches & pots do what.
That is what is missing on the schematic.
The labels are on the circuit board.
They are simply not spelled out on the schematic as to there function.
Which sucks eggs.

[lowell]

I share in the OP's frustration every time I fix one of these.