The dsl joey mod thread

Discussion in 'The Workbench' started by TwinACStacks, Apr 5, 2010.

  1. Cascadem

    Cascadem New Member

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    Last edited: Aug 28, 2016
  2. guitardude57

    guitardude57 New Member

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    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.
     
  3. 6StringMoFo

    6StringMoFo Well-Known Member

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    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)


    Front Board:

    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.


    Mainboard:

    NOTE: THESE MODS AFFECT ALL CHANNELS/MODES

    C9 replace with 1000pf (.001uf) 500V
    C12 replace with 1uf 63V
    -----------------------------------------------------------
     
  4. 6StringMoFo

    6StringMoFo Well-Known Member

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    Aye, Marshall sent me all their schematics hah. I'm doing the mods now.
     
  5. johan.b

    johan.b Well-Known Member

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    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.
    j
     
    Last edited: Feb 6, 2017
  6. Stamminen

    Stamminen New Member

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    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

    Thanks!

    http://www.ebay.com/itm/322359203629?_trksid=p2060353.m1438.l2649&var=511281869560&ssPageName=STRK:MEBIDX:IT
     
  7. dslman

    dslman Well-Known Member

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    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.
     
  8. dslman

    dslman Well-Known Member

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    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.
     
    RickyLee likes this.
  9. Razvan S.

    Razvan S. New Member

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    Hello

    I have been lurking for some time on this thread. I would like to thank Joey for his work, it is priceless!

    I want to add here, the 60-00 version transcription from the thread version with the Notation changes.
    Note the modifications in bold with yellow.
    PLEASE correct me if I am wrong, but I have already rechecked and everything looks right(LE: rechecked now, I can assure that everything is OK :) ):


    I did a simple comparison, and here is transcription for the 100W 60-00 version (from the one in the thread, the 60-02 version), for the Tube (main) board.


    The FRONT board, is the same. So no changes there.


    I want to mention that I did no mods to my amp, and I honestly think it sounds great as is, even at low volumes; however I see that on the 60-00 version, there are some changes and this would suggest why it is sounding better “stock”. The 10K being stock (recommended 5k6 by the guys here) instead of the 220K stock on the schematic. Also, C46 is missing entirely.
    Maybe in the future I will try out some stuff, and jumper everything.
    I have a 2009 Model.

    In brackets I have mentioned with "was'' the notation which is for the 60-02 version, and in the front for the 60-00 version.


    Frontboard(no changes)

    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 ****
    C12 Lower to 150pf or REMOVE (I removed it)
    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.


    Mainboard:

    NOTE: THESE MODS AFFECT ALL CHANNELS/MODES for 60-00 version:

    C4 (was C9) replace with 1000pf (.001uf) 500V

    C7 (was C12) replace with 1uf 63V


    Now if You find that the overall texture of the amp is, or has become too dark:

    Mainboard:

    Replace R18 (was R30) (470k)with 68k to 220k resistor this will Decrease the Fizziness and the OVERALL GAIN as well and also brighten the Amp. I personally Piggybacked, (using a pair of test leads), a range of resistors across the Legs of R18 (was R30) from 82k to 1M and decided I liked 1M the Best. This brought the Value of R18 (was R30) to 320k. I then soldered it in place across the legs of R18 (was R30). This way it is easily changed if I decide on a different value without pulling the PIA Mainboard!!! This particular Mod is pretty much season to taste. One of the Techs or Myself can figure out what value you need for "Piggybacking", or you can try and figure it out yourself:

    R1XR2 Divided By R1+R2= the Total resistance of Both Resistors combined. Use the Value of R18 (was R30) (470)k for Resistor1 and the resistor You want to try as the value for Rresistor2. (Try: 82k, 120k, 220k, 330k, 470k and 1m)

    Also if You find that the Green CRUNCH Mode is too boomy especially with the deep switch engaged:

    Frontboard(NO changes here for notations, because they are the same!)

    C8 replace with .001uf to .0022uf (I used .0015uf)

    Here's a link: http://www.mouser.com/ProductDetail...EpiMZZMsh%2b1woXyUXjyBw8LYChpgf%2bpPFAhHPmAM=


    THESE ARE THE EXTENT OF THE ORIGINAL MODS.


    Now THIS is the "while You are in there" section of the Mods that SHOULD be performed.

    C46 if You have one (this does not exist in the 60-00 Version!!). This is an underspeced Cap that apparently is to prevent parasitic oscillations. It can short out and Take out the board it's on, as well as your OT. Either CUT it OUT or replace it with a +1000V version of the same value (22pf). I say "apparently" because I have heard nothing about anyone experiencing oscillations after removing this cap completely.

    Change out the Grid Blockers on the Mainboard. Most versions have 220K in place, replace with a more normal "Marshall" value 5k6 resistor. I'm of the understanding Alan Bradley Carbon Comps are suited quite well for this, I used regular +/- 5% carbon films from Radio Shack that I had on hand.

    The locations for these are: R55 (was R7), R70 (was R10), R58 (was R66), R62 (was R70)

    (ironically, mine were all 10K (??weird) on the 60-00 version, which is close to 5k6 and I wouldn’t bother changing these, if you have the same on the 60-00 version)

    Also because of frequent run-away biasing problems That appear to be temperature related, Upgrade the Bias resistors. I suggest a more temperature-stable precision metal film 1/4 to 1W, PRP or Vishay Dale.
    Here is a link for the PRPs: Sonic Craft High-End DIY Audio Parts

    The locations and Values of the Bias resistors are: on the Mainboard
    R60 (was R68) 33K
    R71 (was R77) 10K
    R59 (was R67) 220K
    R61 (was R69) 220K


    One last preventive measure, On the rear of the chassis the speaker output jacks should have separate grounds installed. the 4&8 ohm jacks are grounded through the 16 ohm jack, (which Bypasses via an open/close contact), the 4&8 Ohm jacks when the 16 Ohm is used. Sometimes this contact doesn't close because of Dirt etc. so when You are plugged into the 4, 8, or Both, the Amp is actually seeing No load at all and: Bye-Bye OT and Maybe more. If You use only the 16 Ohm jack this is not a concern. This can be accomplished by soldering a short piece of wire to the shoulder of W6 Ground connection and to one of the metal bands on either the 4 or 8 ohm jack that is closest to the inside rear surface of the Chassis. When this is done however there will be no auto disconnect. ALL 3 jacks will be active ALL the time. Please DO NOT try and run 3 Cabs at the same time!!!

    Now for the FUN Stuff:

    Replace the OT and Add a Choke.

    Add a 3H Choke at the R63 (was R71) Resistor (270R 7Watt) on the Mainboard. Remove R63 (was R71) and connect the two wires for the choke in its place. You can mount it behind the power Trans at the Rear of the Chassis. You will need to swing the Powerboard out of the way for drilling. TIP: Because this resistor is mounted with a LOT of solder, (and I was a little afraid of overheating and lifting the traces), I simply snipped the body off the Legs and soldered my wires directly to the leg remnants. Very un-professional and very effective.

    A MAJOR sound Modification is the replacement of the puny Stock Dagnall OT. JCMJMP has drop in replacements on: Marshall DSL
    Also they are available from Mercury Magnetics, I believe Jon deals in these. Because I had a deal fall into my lap, I used a replacement for a 100 Watt Plexi: a Dagnall C1998 or the Later version C2668. These you can find on Ebay or VERY good Clones from Marstrans or Metro Amp.
     
    Last edited: Sep 28, 2017
    dslman likes this.
  10. Razvan S.

    Razvan S. New Member

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    BTW guys, wouldn't the 3H Choke make the amp kind of loose? Wouldn't a 5H or even a 7H be better?
    Thanks!
     

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