AU 20,000 No Power

Discussion in 'Exclusively Sansui' started by sansuilove, Aug 1, 2017.

  1. Overundr1

    Overundr1 AK Subscriber Subscriber

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    2,246
    Location:
    Mississippi
    Need verification before you do this, measure across the two yellow terminals but wait for confirmation from others before this step!
     
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  2. sansuilove

    sansuilove Active Member

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    229
    228 Vac when unit turned off
    231 Vac when unit turned on
     
  3. sansuilove

    sansuilove Active Member

    Messages:
    229
    Hipocrates :
    Yes . That's how I found out R01 is bad.
    Which makes me think - what feeds it that can make it fry?
    Concerning S702 - I get 180Vac at it on both sides doesn't matter if switch is up or down
    o_O
    What's the best way to check it? I checked continuity and it beeps when it's at 'on' position

    Regarding the inrush circuit - would love to hear from you what's that and how to test it
    Thanks
     
  4. w1jim

    w1jim I can fix it but good... Subscriber

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    I believe the "K" refers to the resistors characteristics and 3.9 ohm is correct.
     
  5. Hipocrates

    Hipocrates AK Subscriber Subscriber

    Messages:
    960
    Location:
    Costa Rica
    I don't know on that amp but in general terms is a circuit to limit the initial current demand of the transformer.
    In this case... and Looking the schematic I'll start with C701, which is a 0.01 safety cap, after you already found than R01 an R02 were bad.

    the tricky part here is this. (why does voltages are not close to your readings) Let's wait for the new resistors and what others have to say.

    AU20K.PNG
     
  6. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Location:
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    Personally I would want to know the voltages across the all the windings, powered-on, with nothing connected, all the yellow markings on the secondary side, as per Hipocrates' post above. I would also want to verify that both primaries are OK.
     
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  7. sansuilove

    sansuilove Active Member

    Messages:
    229
    There are 2 groups of wires coming out of the transformer
    These are the primaries I believe?
     

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  8. sansuilove

    sansuilove Active Member

    Messages:
    229
    From the "harmonica terminal" there comes brown wire #4 - it has 228Vac which seems ok per schematic
    But yellow wire #2 which seems as should be the same (both going to R01/R02 on F-2511)
    It gives only 30Vac)
     

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