No sound out of MX110 tuner

Discussion in 'McIntosh Audio' started by joss2178, Jan 5, 2017.

  1. joss2178

    joss2178 New Member

    Messages:
    18
    Found a few web pictures for similar model, that have the C28 cap installed, so I am gonna continue investigating.

    I am wondering, at TP2, I am always getting 0v, whenever I am at a strong radio frequency or not.

    For TP1, I get only negative voltage, around -10v for strong radio frequency and around -0.6v for nothing.

    Those voltage seems ok ?
     
  2. joss2178

    joss2178 New Member

    Messages:
    18
    Finally got some sound! I found in part my problem.

    In the latest version of mx110z, they replaced resistor R42 2.2k with a Zener diode (it is written 758 on it). This diode seems dead. If i test with a resistor, i get music! So now I am wondering if I should put back a working Zener diode?

    Also, maybe it is the cause of my diode being blown out but on the 6cs6, instead of getting around 29v on pins 1,2 and 7, I get around 130v. I am not sure why it is that high and where to look for. Pin 6 of v8, is around 90v. Pin 5 of v6 is around 130v. My psu have been recapped and test around 10% higher.
     
  3. joss2178

    joss2178 New Member

    Messages:
    18
    In fact, my voltage tests on the 6cs6 were before replacing the dead Zener diode with a resistor (only put 1.1k for now). With the resistor I am getting around 17v. Yeah, so my problem should be solve.
     
  4. joss2178

    joss2178 New Member

    Messages:
    18
    So - if I put back a Zener diode 758, will it die because of the 10% increased voltage of the psu (recapped, new Silvio on rectifier) ?

    On the latest mx110z schematic, voltage at 6cs6 should be 10v, not 29v for the first mx110z version.

    So should I consider putting dropping resistor on psu to go to original voltage?
     
  5. joss2178

    joss2178 New Member

    Messages:
    18
    Ok - read more about Zener diode. It is used as a voltage regulator in the MX110z context, so putting a 10v zener (the 758 that was in) will max out voltage to 10v, exactly the specs of latest schematic. So just ordered some of them, will let you know when I get them.
     

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