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A85/P85 - Intermittent Problem

Discussion in 'Arcam Owners' Forum' started by keiths, Dec 27, 2004.

  1. keiths

    keiths
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    Hi All,

    I have experienced the following problem very occasionally for the last 2 years - today was the first time it's happened for about 6 months.

    When playing vinyl, the P85 suddenly shuts down and the A85 mutes displaying the message "DC OFFSET CHECK CONNECTIONS". After waiting a few seconds and powering back on, I can always play the same record at the same volume without problems.

    Relevant hardware is Michell GyroDec, Rega RB300 (re-wired with the Incognito kit), Sumiko Blue Point 2 MC cartridge into Musical Fidelity X-LPS phono stage into Arcam A85 and P85 bi-amping Mission 753s.

    I have checked all connections and used a multimeter to check continuity and there are no shorts anywhere from cartridge tags through to the Audioquest cables from the phono stage to the A85.

    Any ideas what could be causing this?
     
  2. JH1

    JH1
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    Keith,

    Don't know the answer, but I have a CD192 and a Chord DAC 64 on trial this weekend and after I connected up the DAC between my CD player and the amp, my amp shut off momentarily and displayed the same message. I thought I'd made a wrong connection or something but all was correct and it then reset itself and worked fine!! I hasten to add that everything was turned off whilst I made the connections, it was just after I powered back up again that it did this!!???
     
  3. ANDY_DUTTON

    ANDY_DUTTON
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    The A85 has a quite sensitive DC offset detector, this is to protect not only the amplifer but also your speakers from being damaged. This can occasionally be set off by very low fequency noises. Things likely to cause this are power on thumps (or even slow DC settling of Servos, which you can't hear but you would be able to see the speaker bass drive units slowly moving) from any equipment attached to the A85. Also this could be set off by a record deck that has a good low frequency response if the deck gets jogged or even if the floor the player is on bounces.

    It would also be possible to set this off with very badly recorded material if it has extreemly low frequency noise in it.

    Regards,
    Andrew
     
  4. keiths

    keiths
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    Thanks Andrew. The turntable is on a Target stand on a suspended floor. Maybe I need to look at isolation from the floor - maybe a wall shelf or similar.
     

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