Sansui AU719 protection relay repair....please help!

Discussion in 'Solid State' started by mcgreg66, Jan 2, 2018.

  1. mcgreg66

    mcgreg66 Member

    Messages:
    80
    Hi members,
    After infected by the Sansui virus I came across a AU719 in good cosmetic condition but won`t come out of protection........
    I checked a lot of things and took measurements but need some help of the professionals to interpretate and how to go on......
    - when powering on protection led keeps flashing
    - tried to set DC offset - left channel ok! (Incredibly sensitive to adjust!)
    - right channel jumping DC; sometimes staying around 0mV then jumping over 40mV
    - when trying to adjust DC relay starts trying to engage on and on but doesn`t stay

    Checked voltages from the schematic
    - PSU alright; all voltages little under schematic but i think ok! Probably different model series!
    - drivers; both channels get 55v over pin 10 fine!

    BUT now it starts
    RIGHT CHANNEL / LEFT CHANNEL
    TR16 - jumping 0-0,4v should be -0,55v. / Stable -0,57v!
    TR15 - 0,9v falling to 0 going up to 0,9v aso. / Stable 0,63v!
    TR14 - 0,03-0,05v should be 1,15v. / Stable 1,17v
    R38 - 0- - 30mV should be 1,15v. / Stable 1,22v
    So far I went....

    The Protector comes after the drivers......
    So I have for example 43-47v on pin 18 and 37-44v on the relay coil.
    For sure it stays in protection!

    Any suggestions!

    Many Thanks

    Gregor
     

    Attached Files:

    Last edited: Jan 2, 2018

     

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  2. mcgreg66

    mcgreg66 Member

    Messages:
    80
    Maybe better to move this to Exclusively Sansui :rolleyes:
     
  3. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
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    all pin voltages for power supply . protect circuit and main amp circuit should make it easier . . all in nice lists .
     
  4. mcgreg66

    mcgreg66 Member

    Messages:
    80
    Hey Pete,
    Thanks for replying!
    Here is what we need......

    PSU
    Pin01 41V
    Pin02 40V
    Pin03 41V
    Pin04 40V
    Pin15 32V
    Pin16 0
    Pin17 -32V
    Pin27 -18-18mV
    Pin28 -18-18mV

    PROTECTOR
    Pin09 55V
    Pin10 56V
    Pin11 -55V
    Pin12 -56V
    Pin13 0
    Pin14 0
    Pin18 42-46V
    Pin19 0
    Pin21 0,02V
    Pin22 -0,07V
    Pin23 0 but when the relay tries to engage 20V
    Pin24 0 “ “ “ 56V

    .............DRIVER LEFT / RIGHT
    Pin01 0/0
    Pin02 0/0
    Pin03 0/0
    Pin04 56,2/56,5V
    Pin05 0,63/-0,08V !!!
    Pin06 0,03/-0,06V !!!
    Pin07 0,01/-0,06V !!!
    Pin08 -0,575/-0,08V!!!
    Pin09 -56,2/-56,2V
    Pin10 56,2/56,2V
    Pin11 0/0
    Pin12 -56,3/-56,7
    Pin13 20/56V !!!
    Pin14 0,2/0,2V

    Left and right board have different numeration for Pin14 and 11 but they connect the same !
     
  5. petehall347

    petehall347 the brandy coffee man Subscriber

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    its looking to me like you need to be changing the fuse resistors on the driver boards .
     
  6. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
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    but then there is this
    protect
    Pin21 0,02V
    Pin22 -0,07V

    driver
    Pin13 20/56V

    maybe errors with your reading ?
     

     

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  7. petehall347

    petehall347 the brandy coffee man Subscriber

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    right channel has lost base voltages at outputs . pins 5 and 8 should be around +- 600mv
    have you been twiddling the bias pots ? vr02
     
  8. mcgreg66

    mcgreg66 Member

    Messages:
    80
    Yes it’s mV on Pin13 driver boards
    These have direct connection!!!
    Pin21 19mV connected to Pin13 17mV left channel
    Pin22 -71mV connected to Pin13 60mV right channel

    Bias current left channel 23mV
    ....................right channel no bias/not possible to adjust!!!

    I noticed after powered on for a while the relay is ticking like clock and I see it move little but only on left side for left channel....!!!
     
  9. mcgreg66

    mcgreg66 Member

    Messages:
    80
    I had a look for fuse resistors.....and there should none in AU719
     
  10. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
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    best sort the right channel first .
    check
    r36
    r42
    both 33 ohms
     
  11. mcgreg66

    mcgreg66 Member

    Messages:
    80
    R42 33,3ohm
    R36 34 ohm
     

     

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  12. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
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    base voltages
    tr13
    tr14
    see if they adjust with vr02
     
  13. mcgreg66

    mcgreg66 Member

    Messages:
    80
    TR13 -0,48v
    TR14 -0,55v
    No adjustment possible with VR02

    Left channel is
    TR13 1,8v
    TR14 -1,8v

    Thanks a lot that you go with me......
     
    Last edited: Jan 3, 2018
  14. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    26,190
    Location:
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    all voltages BCE
    tr10
    tr11
    tr12
     
  15. mcgreg66

    mcgreg66 Member

    Messages:
    80
    Ok....

    TR10 B-0,57v C-0,48v E-0,55v
    TR11 B 53v C2,5v E53,8v
    TR12 B -53,7 C-1,6v E-54v
     
  16. petehall347

    petehall347 the brandy coffee man Subscriber

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    r29 120 ohms .
    but tr10 base also bad .
    so first check voltages each side of r36

    mmmm .this is odd . tr11 voltages are throwing me off now .
     

     

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  17. petehall347

    petehall347 the brandy coffee man Subscriber

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    am thinking you got tr10 and tr11 mixed up .
     
  18. mcgreg66

    mcgreg66 Member

    Messages:
    80
    Ok I’ll check TR10 and 11 again

    R36 is 55v before and after
    R29 is 120 Ohm
     
  19. mcgreg66

    mcgreg66 Member

    Messages:
    80
    TR10B 53v C2,5v E53,8v
    TR11B-0,57v C-0,48v E-0,55v
    TR12 B -53,7 C-1,6v E-54v

    You’re right I mixed it up
    That’s how it is right
     
  20. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
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    Location:
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    r31 56 ohms
    check that first
     

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