New Dsl20hr, And A Problem...

Discussion in 'Marshall Amps' started by JuSu, Feb 19, 2018.

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  1. tce63

    tce63 Well-Known Member Gold Supporting Member

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    :welcome: to the forum
     
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  2. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member VIP Member

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    :welcome: To the best amp forum there is ! Cheers Mitch
     
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  3. Matt_Krush

    Matt_Krush Well-Known Member

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    Mine has that same noise.
    It's not tubes. Been there done that.

    A noise gate in the loop does not stop it....its in the power amp stage after the pre-amp.
    I've had mine past the 'return' to where I bought it time frame, but it is under warranty.
    I should just break down and send it in.
     
  4. scozz

    scozz Well-Known Member Gold Supporting Member

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    I can relate to that! I’ve got some hearing loss and tinnitus in both ears.
     
  5. solarburnDSL50

    solarburnDSL50 Well-Known Member Platinum Supporting Member

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    For sure. Make them fix it. You deserve a fully working amp. I have no doubt they will.
     
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  6. scozz

    scozz Well-Known Member Gold Supporting Member

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    Sounds like a microphone in the wind.

    Why are there so many, (or it seems like a lot), of these Dsl20 amps with problems?
     
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  7. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member VIP Member

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    :shrug:
     
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  8. RobV

    RobV Member

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    I must have got a good one, I don't have that wind, just a little tube noise I have heard in numerous amps when turning them up, I am actually putting in some EHX's for power & JJ's in the Pre I have tomorrow. No issues with emulated out and headphones work perfectly. $400 dlvd for a new 1 was a good deal :)
     
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  9. Sixstring63

    Sixstring63 New Member

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    It’s not tubes guys. I have one on the bench right now with that same popping crackling noise. It is in the ultra gain stage and has something to do with the crazy volume pot routing via shielded cables. I have changed out anything that would induce that noise on a normal amp with no luck yet. I have the schematic since I do some repairs for a Marshall dealer but they leave out the digital daughter board for the loop and emulated headphone jack. I think that’s t where most of the issues are. I have the dealer trying to get more info to get this thing off my bench and working right. They went off the cliff with changing the topology of this POS compared to the DSL 15’40’100 layouts. Just stupid layout that obviously didn’t work well. The schematic I got from them is DSL15M-60-02-v6, the amp is -60-00-v7 so that shows how many revisions they have done, and it still doesn’t show the factory fix that somebody posted before and after. I’ve modded the hell out of my DSL40 with ease, this bastardized thing is like nothing I’ve encountered. Plain and simple piss poor design on their part. Once again trying to improve the mousetrap. If it ain’t broke, don’t fix it.
     
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  10. mickeydg5

    mickeydg5 Well-Known Member

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    I do not want to hear about their 3rd world cheap crap!
     
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  11. tce63

    tce63 Well-Known Member Gold Supporting Member

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    I had a DSL20HR without any issues, EU version.

    And :welcome: to the forum.
     
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  12. Sixstring63

    Sixstring63 New Member

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    You are one of the lucky ones. From what I’ve been reading people had more issues than not had issues with this model. Once I get it figured out I will share my findings. Traced the noise from second gain stage for ultra channel to loop send. Clean channel is dead quiet. Return loop signal is quiet too. Cheesy dual layered pcb makes impossible to trace it properly without pulling the board to which you can’t power it up out of the chassis. Pretty much a cheap throw away amp if it fails. That’s why I play old Marshall’s and a Friedman SB50. Reliable and easy to maintain with no crazy mp3 input nonsense.
     
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  13. Sixstring63

    Sixstring63 New Member

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    You hit the nail on the head there Bro! My DSL 40 sounded like ass when I first got it. Modded it to my liking. Just bought it for small gigs we do one in while where I don’t have room for my big rig. This 20 is a nightmare layout. Strangest design I’ve seen.
     
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  14. mickeydg5

    mickeydg5 Well-Known Member

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    I should not have bashed it that badly but has anyone noticed more complaints about the new DSL series?
     
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  15. Sixstring63

    Sixstring63 New Member

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    Update! Finally got it figured out. Cap C4 (10nf) coupling cap from V1b to V2a was the culprit. It was throwing me off because the noise was showing up a bit at the grid of V1b too. The DC voltage at V2a was very high at about 11v and that kept telling me something was goofy, the voltage was negative to the cathode so I thought it was what they were after with a 8.2k cathode resistor with no bypass cap. I also replaced C9(1.5nf) in parallel with a 470k resistor that makes up a voltage divider with another 470k going to the grid of V2a. Both of these caps tested fine in circuit and out along with my old Heathkit cap tester at 400v. Little sob sure didn’t work in the circuit. Now I had about a grid DC of 0 and a cathode voltage of about 2.3vdc at V2a. Right in the same range of the other stages. Good lesson learned to trust my first instinct of the issue. I did upgrade quite a few parts that were revised to the newer schematic I got from Marshall. Thing really screams now. Funny thing is they would not give up the channel wiring factory fix that a member posted before and after shots on another thread. I asked the dealer I do work for to get the service bulletin and procedure, but all they sent was the two 1 meg resistor change in the resonance circuit. I found that in another post and tried that first thing. Anybody that has crackling, rustling and popping on the ultra gain channel of one of these change the parts I have listed. Should do it, especially if you have quite a positive dcv on V2a grid. More of these amps than not have these noise issues. Must have got a bad run of 10nf caps on this production time frame. All good other than a lot of time wasted. My fault, should have seen it sooner. Sometimes the stuff that is in front of your nose is the hardest to see.
     
    Last edited: Jun 28, 2019
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  16. Krisztian Nagy

    Krisztian Nagy New Member

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    Wow good job, congrats!
    Could you share this old schematic of DSL15M-60-02-v6?
     
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  17. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member VIP Member

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  18. scozz

    scozz Well-Known Member Gold Supporting Member

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    Yeah, I've been talking about that for months! And the majority of the models too, the 100, 40, and the 20, I haven't heard too many problems with the 5, and I haven't heard about any problems with the 1.

    Last year just about this time, I was all ready to pull the trigger on a Dsl20h. Then I thought I'd wait till after the New Year and NAMM,....to see what, if anything, Marshall would be releasing. Well I can't tell you how happy I am that I did that, I bought a SC20h!
     
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  19. mickeydg5

    mickeydg5 Well-Known Member

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    I
    I guess its that great quality control they are on top of according to their business ethics.
    So how good is Euro-Union when you can send your manufacturing to the back hills of Vietnam getting things made for tuppence on a pound. Or is that part of the reason for Brexit?

    SC20h MADE IN ENGLAND
    Does anyone have to say more?
     
    Last edited: Dec 6, 2019
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  20. Armando

    Armando New Member

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    please can you share more of this work, some pictures will be appreciated

    Thanks.
     

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