Marshall JCM 800 combo 4210, noise issue

Discussion in 'The Workbench' started by Ad1an_, Jun 3, 2020.

  1. Ad1an_

    Ad1an_ New Member

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    Hello,

    I recently purchased 4210 combo. It is an amazing amp and sounds beautiful, besides one issue that I found in it. It makes weird crackling / buzzing noise on certain settings. That weird noise appears only on Boost channel on following settings: Gain between 9,5 and 10; Volume between 7 and 9,5. On Volume set to 10 there is no problem. Also Master Volume only slightly increases level of that buzz, so on high MV settings it is still there but less noticeable.

    Please find below two videos with the problem




    Has anyone ever faced such thing? What could cause a problem ?
    All tubes are new, replaced two days ago.
     
  2. ampmadscientist

    ampmadscientist Well-Known Member

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    You need to clean all the pots and jacks.
    Spray cleaner INSIDE the pot and jack. Rotate several times.
    Use only lubricated non conductive cleaners.
    Deoxit G 100, Deoxit D100, LPS-1 are 3 cleaners that work really good.

    BE CAREFUL about which cleaners you use. DO not rely on a sales person to choose a cleaner.

    sales people are very likely to sell you the wrong types of cleaners because they know nothing about it. Watch out.
    Never trust what a sales person tells you.
    I warned you.
     
    myersbw, kinleyd and tallcoolone like this.
  3. tallcoolone

    tallcoolone Well-Known Member

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    Geez man, I’m a salesperson! We aren’t all out to get you!

    Good advice all the same :yesway:
     
  4. ampmadscientist

    ampmadscientist Well-Known Member

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    Sales people will tell you anything you want to hear. As long as they make a sale.
    And when your pots are destroyed by the wrong type of cleaner,,,that's your tough luck.

    I have seen this happen soooooo many times.
    Those who do not study history are destined to repeat it.
     
    Last edited: Jun 3, 2020
  5. dragonvalve

    dragonvalve Well-Known Member

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    Cleaner and lube together in an emergency although not the best situation.

    Try this below after spraying a straight cleaner:

    [​IMG]

    The better approach IMO is this 2-step process below:
    [​IMG]

    And THEN this:

    https://www.newark.com/electrolube/cg53a35sl/contact-treatment-grease-35ml/dp/57AC5786

    [​IMG]
    This is the grease they put in pots that creates that "hydraulic" dampened feel.

    When a cleaner is sprayed into a pot, it washes away the factory grease.

    I'm not a fan of all-in-one cleaner/lubes for this reason although it will do in a pinch.

    If you can do a better job it would be this way in a two-step-two product process.

    This Electrolube® electronic grease is being used in studio console mixers specially for faders to get back that "resistance" in the sweep AFTER dousing it with a straight cleaner WITHOUT lube.

    I personally would not use Deoxit as they've changed their recipe and pots and switches have been cutting out as it destroys the plastic.:hmm:
     
    Last edited: Jun 3, 2020
    Dwayne Eash likes this.
  6. Ad1an_

    Ad1an_ New Member

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    All pots and jacks has already been cleaned, so it must be something else. It is not the sound of scratchy pot. You can clearly see and hear it in 2nd video.
     
  7. dragonvalve

    dragonvalve Well-Known Member

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    I think this is the problem..:naughty:



    Don't know man, never heard that before out of an amp.

    You next to a 5G tower perhaps??

    [​IMG]



    [​IMG]
     
    Last edited: Jun 3, 2020
  8. myersbw

    myersbw Well-Known Member

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    AMS gave good advice. Still, just because you cleaned them doesn't mean the pot isn't defective. Showing the issue 'at the same place in the rotation' seems to point to a defective pot or a thorough cleaning.

    Sometimes folks do one of two things to pots...way too much of a cleaner (or the wrong cleaner/process) -or- just a one time squirt on a pot that's decades old and never cleaned...ever. And, if the latter, the lack of a 'good and proper' cleaning is just pushing a little debris around that's settled into the area of suspect on that pot.

    Take AMS' advice and explore proper cleaning process with the right products. If a repeat (and correct) cleaning shows no difference, consider swapping (or subbing out) the pot for another. Measure the pot with a DMM to see if you happen to have some DC voltage on there while opened up first.

    I don't know you're tech level...?...as to what you're capable of.
     

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