sansui 8000 blowing lights

Discussion in 'Exclusively Sansui' started by maclvrbr, Nov 10, 2017.

  1. ManyMoonsAudio

    ManyMoonsAudio AKA paul79 Sponsor Subscriber

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    I would say your bulbs are junk. Get some good ones from Dwojo.
     
  2. LBPete

    LBPete Rolling Along Subscriber

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    You're right, there's not much you can do other than change out the transformer. The concern is that all the transformer output taps are putting out too much voltage. That will stress components down stream.

    Are you reading these voltages on power supply board F-2808? If so, you should have 7.5 V AC at F03 and 43 V AC at F01 and F02. These values are both more than 20% higher voltage than the specification. The ratio of overage is almost identical for both of those values. That would make me very nervous.

    Check the A/C voltage on the fuses on the other power supply board, F-2807. If they are also 20% high, you either have a bad transformer or you line voltage is 20% high.

    - Pete
     
  3. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    The bulbs that went out are from him. The longer life bulbs are rated up to 14 acv.
     
  4. deltalight

    deltalight AK Subscriber Subscriber

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    What is your measured Line input voltage? It all starts here!
     
  5. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    will do thanks
     
  6. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    120 acv from wall outlet
     
  7. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    The other fuse voltages are from front of unit to back. yellow 40acv, 56 acv, 56 acv, 40, 54, 54.
     
  8. LBPete

    LBPete Rolling Along Subscriber

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    Without color or fuse number reference it's hard to tell what is what, but all of those voltages are too high. The yellow wires should be 32v, the brown, 45v and the blue 43v.
    Your values are actually higher than what is specified for a G-9000 and it has almost 50 watts more power output. Here's the power supply schematic for a G-8000. It contains the specified values for each of the transformer outputs.

    I've never seen anything like this so I don't have a good recommendation but at these voltages, stuff is going to over heat and fail.



    - Pete
     

    Attached Files:

  9. ManyMoonsAudio

    ManyMoonsAudio AKA paul79 Sponsor Subscriber

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    Damn strange situation here... Nice detective work there Pete!
     
  10. Robisme

    Robisme Sansui Enthusiast Subscriber

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    Well, he could always run it off a big variac.:biggrin:

    Rob
     
  11. ManyMoonsAudio

    ManyMoonsAudio AKA paul79 Sponsor Subscriber

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    Since it is a G-8000 and finding a transformer will be next to impossible, I sure would!
     
  12. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    Quite a learning experience here. After speaking with a tech friend he suggested revisiting the voltage selector plug which I did and found it was actually int he 100 v setting. After plugging it in the 120 volt section, I now have 7.6 acv feeding the lamps and the other voltages have dropped very close to the schematic voltages.
     
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  13. Robisme

    Robisme Sansui Enthusiast Subscriber

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    Well, that will do it.

    Pete was on the right track.

    Rob
     
  14. slimecity

    slimecity Super Member

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    Good spotting here Pete.
     
  15. slimecity

    slimecity Super Member

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    Yikes!

    Good spotting here too - hopefully it hasn't been on that setting for too long, as too much voltage can shorten life of components.
     
  16. LBPete

    LBPete Rolling Along Subscriber

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    It had to be something like the voltage selector. Just too weird for a transformer fault to raise all the output voltages by the same percentage. The difference between the 100V setting and the 120v setting is right around 20%, the same as the increase in output voltage.

    It's a good thing it blew the bulbs. Without that tip, you may have had catastrophic failure with this over voltage.

    - Pete
     

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