Problem with DSL 401 Overdrive

Discussion in 'The Workbench' started by ALan189, Oct 16, 2012.

  1. ALan189

    ALan189 New Member

    Joined:
    Oct 16, 2012
    Messages:
    7
    Likes Received:
    3
    Hi guys,

    I'm new here and I hope you can help/advise!

    I have a Marshall JCM 2000 DSL 401 which is amazing and has never let me down. Slight problem however...

    I have noticed the other night that my amp will not enable the OD2 mode. The red light comes on etc but before it used to be louder and with lots more gain but now there seems to be no difference between OD1 and OD2.

    I have tried switching via the foot pedal and with the physical button on the amp. Both enable the OD2 mode (with red light on) but with no actual sound difference.

    Any help on this would be appreciated.

    Thanks,
    Alan
     
  2. thrawn86

    thrawn86 Well-Known Member

    Joined:
    Aug 6, 2009
    Messages:
    6,722
    Likes Received:
    1,762
    Possibly a loose connection in the amp itself if it's not the jack doing it. Otherwise, maybe you've got a preamp tube going on you. V1 and V2 positions have a lot to do with the gain stages in the 401.

    I'll let the real experts chime in.
     
  3. ALan189

    ALan189 New Member

    Joined:
    Oct 16, 2012
    Messages:
    7
    Likes Received:
    3
    Thanks for your response.

    Anyone else got any input?

    Thanks,
    Alan
     
  4. scat7s

    scat7s New Member VIP Member

    Joined:
    Nov 19, 2010
    Messages:
    13,874
    Likes Received:
    7,292
    thats the first thing to eliminate.

    a preamp tube. i cant remember the signal path in the 401, but it sure does sound like one triode in one of your preamp tubes is dead.

    get a new 12ax7 and put it in V1 slot. no help? put the original tube back in V1 and your new tube in V2. etc...until you either find/solve the issue or eliminate a tube it as the issue.

    seems likely it would be v1 or v2...
     

Share This Page