Discussion in 'The Workbench' started by TwinACStacks, Apr 5, 2010.
I have a DSL 40C here, with the board DSL 100-60-00 Series one. Has the single large board. Have you a schemo and mod list for this creature? All my schemos for the DSL stuff does not really match up.
Someone has the resources to translate?
My Main board is a JCM2-60-00 ISS20
My front board is a JCM2-61-00 ISS345
Looking to translate this components.
JCM2 60-02 iss5 (Tube) AND JCM2 61-00 iss1 (Front)
NOTE: THESE MODS AFFECT THE RED LEAD 2 MODE ONLY (removing C12 will also darken Lead 1)
1M Resistor from Wiper to Ground on Vr3 **** (DONE)
C12 Lower to 150pf or REMOVE (I removed it) (DONE)
C10 replace with .0022 uf
R20 Remove and JUMPER
**** These can be bridged on the other side of the Board. Find the 4 Pins that are the Actual Pot terminals, (Not the Two Board mounting pins), follow the Traces. The inner one that has R19 on it is the WIPER, the outside one that connects to Con 5 pin 2 is the Ground. ( Using your meter set to continuity works well here) Solder your 1M across these 2 pins leaving the legs long, then bend flat to board using a piece of electrical tape attached to the board to insulate the leads from accidentally shorting out to any other exposed solder connections. Electrical splicing tape works quite well here as it adheres to the board better than vinyl electric tape.
NOTE: THESE MODS AFFECT ALL CHANNELS/MODES
C9 replace with 1000pf (.001uf) 500V
C12 replace with 1uf 63V
Aye, Marshall sent me all their schematics hah. I'm doing the mods now.
Another thing you can do is increase r21 (referring to old schematics) on the pot board to 470k-1M. It's originally 150k and it cuts low end in od1 to keep things focused. But it's too much and makes the bass eq knob ineffective and the channel thin compared to green channel. Increasing it restores the low end and makes the bass knob effective again. You can cut it out all together, but bass will be very compressed and fuzzy. .some might like that though. ..choosing value is a balancing act and some compromise will have to be accepted, but it's about restoring the low end that was lost where as the c12 mod is compensating by cutting the high end too..i preferred it this way, but someone else will have to try and say what they think.
Quick question guys, I'm planning on doing the C12 mod on my 2003 DSL50 once I decide to open her up. Finding the red channel to be to brittle like everyone else.
Instead of clipping it completely I'd like to replace it with a different value. I don't know much about caps, but is this what I should be buying? Link is to an eBay seller. If I need a different kind of cap let me know.
I'm planning on possibly trying a 68pF, 100pF or 150pF
Sorry you didn't get an answer, I don't get to this thread much any more, and looks like I'm not the only one.
The answer to your question is yes. I went with a 331pf cap in mine. Tried several values as well as clipping it--which sucked the sting and gain out of the amp.
Mine is a DSL50 also.
Here's a added safety touch for the ohm selector switch on the 2K DSLs,
I saw a video where the tech. had a problem with the switch , since it is only connected by the solder pins.
After he repaired the amp he put some hot glue around the outside of the switch and the chassis, for more stability. This may be splitting hairs, but I did the same.
Should be a bit more sturdy when using the switch.
20170430_111751_1493577492614 by dslman posted Apr 30, 2017 at 2:39 PM
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