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Mesa Boogie 400 (NOT 400+) - anybody got a manual?

Discussion in 'Amps [BG]' started by dukeplaysbass, Dec 19, 2013.

  1. dukeplaysbass

    dukeplaysbass Supporting Member

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    Just picked up a Mesa 400 (not the later 400+).

    Great sounding amp, but switching on the EQ (from the swx in the front) kills output entirely.

    Anybody know why?

    And does anybody have a manual for this puppy? I've downloaded the 400+ manual from the Mesa website, but I hear tell of the original 400 manual out there. If somebody has a copy, I'd love to get it.

    Thanks!
  2. dukeisdog

    dukeisdog Supporting Member

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    Try plugging and unplugging a regular 1/4" cable into all of the jacks several times and report back. I'm no expert but I see a lot of people saying to try this while trouble shooting an amp.

    You're gonna love that 400 when you get it going 100%. The graphic EQ is great.
  3. MesaBoogie

    MesaBoogie Gold Supporting Member

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    Disclosures:
    Customer Service/Product Specialist: Mesa Boogie
    The "owners manual" for the Bass 400 is simply 4 typed pages - shoot me an email and I'll send a copy over. gnoble@mesaboogie.com

    Occasionally the switch gets "stuck" halfway and can be the cause of signal loss, but more likely its a component related issue.

    When the EQ is engaged, is there any hum? Does the hum change when the sliders are moved up and down? Or is there no signal at all? This is the more likely scenario, and will need to be seen by a technician.

    Let me know if you have any questions or need assistance in any way. Thanks!
  4. dukeplaysbass

    dukeplaysbass Supporting Member

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    Sent you an email! Thanks for the offer!
    When the EQ is engaged, there is a little hum, and it changes when the sliders are moved. But no signal from the bass.
  5. MesaBoogie

    MesaBoogie Gold Supporting Member

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    Disclosures:
    Customer Service/Product Specialist: Mesa Boogie
    I just sent you the manual - most likely its Q1 (the first transistor - MPSA-63) in the EQ circuit. Mesa part number is 520635.

    Let me know if I can help in any way. Thanks!
  6. Bassragerstitch

    Bassragerstitch

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    also maybe put some electric cleaner in the eq switch. I had this weird volume swell issue and found the switch was at fault, I put some electric cleaner in there and flipped the switch a few times... problem solved.
  7. MesaBoogie

    MesaBoogie Gold Supporting Member

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    Disclosures:
    Customer Service/Product Specialist: Mesa Boogie
    In some cases, yes - but this time its coming from straight from Mike B. Tell-tale sign that Q1 has failed. Thanks!

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