JVM 205h HELP!

Discussion in 'Marshall Amps' started by predsednikov.sin, Jun 11, 2019.

  1. predsednikov.sin

    predsednikov.sin New Member

    Joined:
    May 29, 2019
    Messages:
    8
    Likes Received:
    3
    hi, first of all sorry for my english ,but il try my best.i need help from JVM owners,ex owners or somebody who knows marshall amps well.

    recently i purchase a used jvm.And it sounds awesome..cleans,dirt,texture.But,after an hour of playing PT gets louder.Its that 50 or 60 hz mechanical buzz in PT area..between PT and phase inverter.It works flawlesly on the output,but something is buzzing.

    Should i panic or thats normal on JVM?

    Cheers from Novi Sad :)
     
    Mitchell Pearrow likes this.
  2. Len

    Len Well-Known Member

    Joined:
    Sep 13, 2009
    Messages:
    985
    Likes Received:
    748
    My JVM215C didn’t have any problems like that.
     
    predsednikov.sin and tce63 like this.
  3. pedecamp

    pedecamp Well-Known Member

    Joined:
    Dec 7, 2009
    Messages:
    12,606
    Likes Received:
    8,027
    How do you know its the PT making the noise? Did you clean all the tube sockets, inputs and pots, put new tubes in it and bias? Since its used I'd take it to a tech to give it a once over if you cant do it yourself, it will be well money spent on your investment, they can check everything inside and make sure the previous owner didnt do any funky mods to it.
     
  4. scozz

    scozz Well-Known Member

    Joined:
    Jul 20, 2008
    Messages:
    1,253
    Likes Received:
    2,416
    ^This is very good advice!

    Unless you’re an amp guy,....and your obviously not or you wouldn’t be asking. :D

    Find a good amp tech in your area and give them a call or email. :cool:
     
  5. predsednikov.sin

    predsednikov.sin New Member

    Joined:
    May 29, 2019
    Messages:
    8
    Likes Received:
    3
    well,thing is i know something about tube heads :).I owned H&K switchblade ,Crappy bugera 6262 but this is my first Marshall.

    Tech said that the amp is in perfect condition,everything is like new and original,voltage is good,he measured tubes (original ,stock marshall tubes ,10 years old) and they are perfect .He said that screws on PT have been loose,and that he tighten him but said something that new models of PT are welded and it can be better.

    Before we went to the tech ,soon as i switch power on it stars buzzing.After the tech session it starts buzzing after 45 min....1 hour of playing.And that is whats confusing me.I read something about old electrolites,old filter caps may be the problem...but i guess that tech wolud see that .
     
  6. pedecamp

    pedecamp Well-Known Member

    Joined:
    Dec 7, 2009
    Messages:
    12,606
    Likes Received:
    8,027
    I think you need to take it to a different tech. Caps etc. arent old in a JVM, my 2204 is 37 years old and has all original caps etc.
     
  7. predsednikov.sin

    predsednikov.sin New Member

    Joined:
    May 29, 2019
    Messages:
    8
    Likes Received:
    3
    second opinion,thats the plan.

    i am confused because there is no hum or weird noises in speakers.

    i know that PT can be noisy,but no idea how much is loud.

    thanks guys,
     
  8. MonstersOfTheMidway

    MonstersOfTheMidway Well-Known Member

    Joined:
    May 1, 2008
    Messages:
    4,701
    Likes Received:
    2,068
    @OP: What you are describing is not normal.

    The problem/issue could be lots of things are thing point: it could be a tube; it could be a component that isn't soldered correctly; it could be a capacitor that is failing; lots of things that are probably best left to a tech to check out (maybe try a different tech).

    Based on the description, I'd say it might be heat related because it seems to happen only the amp has been on for a while.

    What year is your JVM?

    *Check to see if you have fuses at FS3 andFS4 on the pcb.
     
    predsednikov.sin likes this.
  9. predsednikov.sin

    predsednikov.sin New Member

    Joined:
    May 29, 2019
    Messages:
    8
    Likes Received:
    3
    Exactly,when he heats up it starts buzziing around PT or phase inverter.

    i will find different tech.

    made in 2009
     
    EADGBE likes this.
  10. EADGBE

    EADGBE Active Member

    Joined:
    Dec 13, 2009
    Messages:
    385
    Likes Received:
    187
    10 years is old for today's tubes. Yes take it to an amp repairer and see what he says. He may have to leave it on for a while to figure out what the problem is. Good luck!
     
  11. Sacalait

    Sacalait Active Member

    Joined:
    Oct 15, 2012
    Messages:
    82
    Likes Received:
    232
    Location:
    South Louisiana
    I have a JVM205H for six years now and no problems at all.
     
  12. mickeydg5

    mickeydg5 Well-Known Member VIP Member

    Joined:
    Sep 30, 2011
    Messages:
    21,176
    Likes Received:
    8,861
    Location:
    US of A
    You mentioned the PT and PI area which also includes the power tubes.

    Did you try retensioning the tube socket prongs for those tubes for better seating?
    Also get a good lubricating contact cleaner and apply it to all tube pins and socket prongs as well as jack contacts.

    Make sure the PT secondary filament/heater center tap is clean and has a good connection.
     
  13. MonstersOfTheMidway

    MonstersOfTheMidway Well-Known Member

    Joined:
    May 1, 2008
    Messages:
    4,701
    Likes Received:
    2,068
    Another thing you can look at is how you are supplying power to the amp.

    *Try using a different amp at the same power outlet to see if the same problem happens or not
    *Try using the amp at a different power outlet to see if the problem goes away or remains.
    *If you're using extension cords or power strip, try using a different extension cord or different power strip (or disconnect any extension chord and/or power strip) to see if the problem goes away or remains.
    *Remove any pedals/effects from the signal chain while you are testing different power sources; at this point you just want to test the amp with a guitar and not the effects.

    The source of the problem might not be the amp. Trying some of the things I mentioned above are quick, easy, and probably won't cost you any money and are relatively safe procedures.

    Heater fuses at FS3 and FS4

    Since it was made in 2009, you might want to check the pcb at FS3 and FS4 ("FS3" and "FS4" should be printed directly on the pcb). If you pcb has fuses at FS3 and FS4, you might want to get a tech to remove the fuses and the fuse holder, then replace those components with a solid wire. Several years ago a service bulletin was issued from Marshall that explains the procedure and materials needed. At this point it's a little hard to tell whether the fuse holders at FS3 and FS4 are the culprit behind your noise issues, but it's at least a good thing to look at.

    Why remove the fuse holder at FS3 and FS4? In the past, some early production Marshall JVM amps experienced a failure at FS3 and FS4 that sometimes resulted in burning/charring of the pcb at those points. Some owners experienced warning signs before the failure (such as noise) and some owners detected nothing until a sudden failure occurred. FS3 and FS4 are heater fuses, but the fuses were usually not at fault-it was the fuse holders/clips that were the problem in most cases.

    I want to stress that not all JVM amps suffered damage that had fuses at FS3 and FS4, and only early production JVM amps were equipped with fuses at FS3 and FS4. I'm not sure when the production change was made to remove FS3 and FS4 (maybe some time in 2009), but a JVM amp made in 2009 might have those heater fuses, so it's worth looking into. I have a stock JVM410H made in 2007 that has heater fuses at FS3 and FS4 yet I've never in my 12 years of ownership experienced any kind of problem with the amp, so I left the heater fuses in (I later learned it might have bee a bad batch of heater fuse holders that were the culprit, so I figured I got a good set).

    So, yes, I suggest taking the amp to another tech and see what he/she finds. I know it can be frustrating having to shop around for techs, but it's worth it the effort and finding a great tech is so valuable.

    Good luck with your amp. Let us know what you learn.
     
    predsednikov.sin likes this.
  14. predsednikov.sin

    predsednikov.sin New Member

    Joined:
    May 29, 2019
    Messages:
    8
    Likes Received:
    3
    another tech said that amp is fine :wallbash:."quality build amp,with low working hours.

    Thing is,that in Serbia its easier to find submarine tech than amp tech....and Nikola Tesla lived in my area .

    tell me that i am crazy
    this buzzing strart after an hour.
     
  15. Heavy101

    Heavy101 Member

    Joined:
    Mar 14, 2016
    Messages:
    79
    Likes Received:
    31
    Location:
    S.E. Michigan
    First of all, you aren't crazy, that is a pretty good buzz.

    Second of all, when the amp is scoped and gets a clean bill of health
    be relaxed that it isn't a faulty transformer.

    This can happen with 50 watt PT Marshall transformers, the
    answer is to decouple the transformer from the chassis by using
    Nylon Spacers (3mm) for each bolt.

    If you contact Marshall and are persistent they will send an aluminum
    ring spacer to an authorized technician but it may or may not ever
    happen, see you are in Europe so you have a better chance of getting
    the spacer.

    From Marshall's perspective the amp isn't faulty, these amps are made
    for stage amplification and one would normally never hear the buzzing
    at the volume these amps are meant for. Turn it up to 5 and see if you
    can still hear the buzz?
     
    Last edited: Jun 14, 2019
    rrguitar1 and predsednikov.sin like this.
  16. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member

    Joined:
    Jul 2, 2018
    Messages:
    6,930
    Likes Received:
    9,484
    Location:
    Moreno Valley CA
    Welcome to the forum
     
  17. fifteenohms

    fifteenohms Well-Known Member

    Joined:
    Sep 30, 2010
    Messages:
    1,071
    Likes Received:
    534
    Location:
    Los Angeles, CA
    I like that nylon washer decoupling idea.

    I suspect by this sound clip the tranny is arcing to ground somewhere.

    If the chassis is out of the cabinet, place on a table or board and inspect the transformer and octal sockets for spark arcs or plasma light.
     
  18. predsednikov.sin

    predsednikov.sin New Member

    Joined:
    May 29, 2019
    Messages:
    8
    Likes Received:
    3
    i'm a curious type of guy..and i like to experiment.But,if i start to disassembling it on my own....he is gone :).I will try to find 3rd TEch.Those two guys/tehc said the same:"perfect condition ,only that physical buzzzz":wallbash::wallbash:..btw. both techs are building very good bassman amps,custom tube amps...old school techs.

    i really appreciate your help..
     
  19. predsednikov.sin

    predsednikov.sin New Member

    Joined:
    May 29, 2019
    Messages:
    8
    Likes Received:
    3
    im in EU but im not in EU..it's complicated :) ...so ,ordering from marshall is not an option.You are right ,You are right ,i can't hear it when i play on 1 but somethimes when i play on very low voume i can hear it.

    i can get used to that sound , but im afraid of burning the amp:).
     
    Heavy101 likes this.
  20. Heavy101

    Heavy101 Member

    Joined:
    Mar 14, 2016
    Messages:
    79
    Likes Received:
    31
    Location:
    S.E. Michigan
    You could get one of the two technicians to put the nylon spacers
    in, tell them the buzzing drives you nuts and want to put it to an
    end for your own piece of mind.

    Mention that Marshall will send aluminum rings when requested
    and using nylon spacers would be an improvisation.

    If the first two won't then you'll have to find a third tech, hopefully
    it won't come to that though.

    Good Luck
     
    Mitchell Pearrow likes this.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice