G6000 protection problem.

Discussion in 'Exclusively Sansui' started by anderslober, Oct 13, 2017.

  1. anderslober

    anderslober Yikes...not again!

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    Ok...I powered up without driver board. I had hoped this would close the protection relay. Sadly it didn`t. This must mean that the problem is somewhere in the protection circuit and not the driver board(previously tested in another unit).

    IF everything is a-okay, shouldnt the relay click without the driver board installed? I have read this on a couple of threads here on AK. Please confirm......thanks.

    Just for info....the outputs are brand new and tested mj21193\21194`s.

    I have a feeling its some small friggin diode or resistor messing things up......any ideas?
     
  2. anderslober

    anderslober Yikes...not again!

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    Man...I am conundrummed......with driver board installed, I have about 5mv both sides...measured at relay. With driver board out...I have about 300mv bothe sides...measured at relay....what gives?

    All voltages are normal and stable......just no friggin relay click. Everything looks and measures normal. I also changed the relay to a relay that I knew was fine.....still no click.

    Scratch head....
     
  3. slimecity

    slimecity Super Member

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    I cant speak for your amplifier however this has definitely been occurring on the sansui X1 I am working on. Remove the driver boards and the speaker relay clicks in (otherwise I am also having issues setting DC offset at the driver stage, once these boards are put back in).
     
  4. anderslober

    anderslober Yikes...not again!

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    With driver board out.....no relay click. That is my problem. The driver board works for aure, as it was tested in another g6000 that I had.

    So I have a problem somewhere else. I also disconnected all the power supplies to rf, eq, tone........still no relay click.

    So I am thinking the problem is somewhere in the main powersupply/protection board.....
     
  5. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Have you checked for the correct voltages in the protection circuitry - especially to the relay coil ?

    Sorry Anders, I don't know the G-6000 well enough to know if you should get a relay 'click' with the driver board removed.
     
    Last edited: Nov 10, 2017
    slimecity likes this.
  6. anderslober

    anderslober Yikes...not again!

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    Hi John....yes checked...seems ok.

    My power indicator light is out. It is a small green led. Tested with diode test...both way are `ol`.

    Does that tiny green led really run on 48v?..??
     
    Last edited: Nov 10, 2017
  7. anderslober

    anderslober Yikes...not again!

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    I am measuring 48v at the relay diode zd605.....is this correct? The relay is a 24v dc relay......

    My tuning signal meter doesnt budge......but the tuning works fine....stereo light comes on when tuned to a station.
    I have tweaked vr11 on tuner board a bit.....no joy.
     
    Last edited: Nov 10, 2017
  8. anderslober

    anderslober Yikes...not again!

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    Any ideas guys? Check above post about relay voltage........

    Thanks.
     
  9. kevzep

    kevzep Its all about the Music Subscriber

    I have a few mins now, I'll have a look at the schematic.....I wouldn't think you'd see 48VDC on a LED......
     
  10. anderslober

    anderslober Yikes...not again!

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    Hi Kevin.....yes, it seems like quite a bit of voltage on a tiny green led power light.

    I disconnected all that I could from the PS board.....RF, tone, phono....all connections associated with power. Also no driver board. Still no relay click. I dont get it. I also desoldered ALL tr`s on the PS board.....ALL tested a-okay. Voltages are fine.

    Pre-relay voltage is about 3-400mv both sides......I just cant figure where this volatge comes from. The relay is a 24vdc relay, but voltage both sides of the relay diode is 48vdc....is this correct??
     
  11. kevzep

    kevzep Its all about the Music Subscriber

    Whats the voltage across the relay coil?
     
  12. anderslober

    anderslober Yikes...not again!

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    Isnt that what I am measuring at the diode?48vdc........
     
  13. kevzep

    kevzep Its all about the Music Subscriber

    Yes it is. Okay that's high.
    I only have a G7000 schematic I am assuming its the same board. Just to be clear, its the speaker output relay? Not the soft start relay?
     
  14. kevzep

    kevzep Its all about the Music Subscriber

    And no, I do not think the Power/protection LED should be running on 48VDC. It looks like it runs from a 30VDC supply through a 15KΩ resistor.
    There's a lot of MV12 diodes in there too, check all those and/or replace them with 1N4148 in series...
     
  15. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Yep, regulated 30V from the series regulator whose 'pass' transistor is TR605 (on F-2858) and then through that 15K resistor. If you are seeing 48V there then maybe you should check the regulator output voltage as it may not be regulating at all. Kev is correct again, there is an MV-12 (D609) located in that regulator which would cause that kind of problem if it was defective. (2 x 1N4148 in series would be the replacement). ;)

    BTW: There are some horrendous errors in that area of the schematic, just one is C609 (10µF 63V) associated with the protection circuit, which is shown reversed - but may be OK on the PCB itself. :)
     
    kevzep likes this.
  16. kevzep

    kevzep Its all about the Music Subscriber

    There are horrendous errors on that schematic.
    I am thinking there is a regulation issue, and I think its whats root of the issues with the protection as well.
    Just get in there and change out those MV12's, there could also be a shorted transistor in there too....
    You'll just have to systematically work through it.
    These sort of faults are no fun at all, and can also be very frustrating....

    Let us know how you get on...
     
  17. anderslober

    anderslober Yikes...not again!

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    ALL mv12`s changed to 1n4148`s in series.
    This unit (g6000)has no soft~start relay. So, the 48vdc is measured at both ends of the relay diode.(brand new also).

    I will check all the tr`s again.........

    The power led is powered through 2 big white resistors(r602/603).....not at all through pin36.....I have tested the resistors...they are good. It is factory. I will take a photo.

    There are MANY mistakes in the SM! Typical Sansui! On g6k scat there is only 1 big ceramic resistor r603.....but in my g6k there are 2! R602/603. Just like a g7k!

    Is anyone out there with a g6000 or g7000 willing to pop the hood and snap some good ps board photos? Maybe a wire has been swapped or something.....?
     
    Last edited: Nov 20, 2017 at 2:55 AM
  18. kevzep

    kevzep Its all about the Music Subscriber

    Right, okay I am not even looking at the right schematic. In this case I actually do not have one...
    I would probably be more help if I was looking at the right one...
    Do you have a copy you can post here?
     
  19. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Last edited: Nov 20, 2017 at 3:18 PM
  20. Zeacon69

    Zeacon69 Sansui-G-

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    yes if all is well the relay will click and power light will turn on without the driver card , I have done it to mine
     

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