sansui g8000

Discussion in 'Exclusively Sansui' started by maclvrbr, Oct 8, 2017.

  1. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    I see the speaker relays cannot work with out RL 03 correctly operating. I assume now what I have is a signal problem. After c;leaning the switches I now do not have either right or left signals from headphones , thanks for the guidance
     
  2. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    I have confirmed all relays are working correctly . Also the right channel does work but left channel is missing thanks.
     
  3. LBPete

    LBPete Rolling Along Subscriber

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    It sounds like it's in protection. The output signal passes through the MY4 relay before going to the two LY2 relays. These are the three relays grouped together on the power supply board. Next to these relays, there are two coils each with a big resistor in parallel. The amplifier output circuit passes through them before going to the relays. Measure the voltage between chassis ground and each of these resistors. That will give you a close approximation the DC offset voltage. If its higher than 100mV or so it will kick into protection. If it's not too high, you can adjust it down with the trimmers on the driver boards.

    - Pete
     
  4. LBPete

    LBPete Rolling Along Subscriber

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    You posted while I was writhing my last post. If you have normal sound from either channel, it's not in protection and the relay coil circuits are working. Do you have another amplifier or receiver that has pre-outs? Connect the pre-amp of the other amplifier to the amp of the G-8000. This will tell you if the channel drop is in the pre-amp or amp of your G-8000.

    - Pete
     
  5. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    Yes the receiver is not in protection red light blinks for a few seconds then green light appears solid, also Dim bulb is barely illuminated,, From preouts to auxillary of another receiver I still only have left channel with sound.
     
  6. LBPete

    LBPete Rolling Along Subscriber

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    No, not pre outs to aux. Move the connected/separated switch to separated and connect the pre out of the other amp to the Main in of the big G. This will bypass the pre-amp in the G. If that gives you sound from both channel, you know the amp section is good and the channel drop is in the preamp section of the G.

    Before you do that, have you jumpered across the pre-out/main-in of the G? This will bypass the connected/separated switch. Use the shortest RCA cables you have. This will test the connected/separated switch. If you get sound from both channels when you do this, the switch is the problem.

    - Pete
     
  7. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    I jumper ed the preout- main in connections still one channel operational. Connected a cd player to main in connectors of the G and still only one channel operational
     
  8. LBPete

    LBPete Rolling Along Subscriber

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    That brings us back to the relays. Do you have a small speaker a piece of speaker wire and a couple of alligator clips you can use for testing? If so, and you can carefully connect that test speaker to a point on a circuit board, go back and look at post #23. Connect one lead of the speaker to chassis ground and touch the other lead to each of the resistors mentioned in post #23. This will test the amp circuit up to the speaker relays. Be very careful when you do this, not to touch anything else.

    - Pete
     
  9. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    Thanks for the help, I did get sound from one set of resistors but did not from the other set.
     
  10. kevzep

    kevzep Its all about the Music Subscriber

    Have you tried some headphones? This will narrow down whether its the speaker relays or not.
    If you have not got audio in both channels then it is very likely in the power amp for that channel.
     
  11. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    I have used the headphones only one channel audible
     
  12. kevzep

    kevzep Its all about the Music Subscriber

    I think the problem is back in the amplifier. The relays are not the issue I'm thinking.

    Okay so we know the issue is in the power-amp, that narrows it down a lot.
    Have you measured the bias to see if theres current flowing though the circuit?
     
  13. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    I will check it, the manual states checking bias using TP+ and TP- for 16mv, I cannot find these test points, pg 12 of service manual, thanks
     
    Last edited: Oct 10, 2017
  14. dr*audio

    dr*audio Fish fingers and custard! Subscriber

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    TP + and - are on small terminal strips in the 2 rear corners.
     
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  15. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    Capture.JPG
     
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  16. maclvrbr

    maclvrbr AK Subscriber Subscriber

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  17. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    left rear bias .9 mv, right rear bias 0mv. Ideas? I also connected a cd player into aux input on G and did not get sound from either channel.
     
  18. LBPete

    LBPete Rolling Along Subscriber

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    The bias test point terminal strips get oxidized. It's sometimes hard to make a good connection. Scrape a shiny surface on them and test again. 0.9 mV is essentially zero so you probably are not getting a true reading.

    Did you have the connected/separated switch in the correct position? When you connect to the aux or any of the other normal inputs the connected/separated switch has to be in the connected position. If you connect to the main in that switch should be moved from "connected" to the middle position.

    In the various tests, when you get sound from one channel, is it always the same channel with sound?

    Here's a picture of the speaker relays on a G-9000DB. It's very similar to a G-8000. You see the gray covered coils with the big gray resistors with two red stripes on either side of them. The audio output from each channel of the amplifier passes through these coil/resistor combinations. Did you touch your speaker wire to the conductor of each of these resistors? When you say you got sound from one side, was it fairly normal sound?

    G9000DB Speaker Relays.jpg

    - Pete
     
  19. maclvrbr

    maclvrbr AK Subscriber Subscriber

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    yes Pete the sound was normal , as mentioned I only got sound from the resistor on the left sie closest to relay. No sound from the resistor on the right ( between the 2 relays), thanks for the help again. I did think the values were low and will recheck bias.
     
  20. LBPete

    LBPete Rolling Along Subscriber

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    If you didn't get sound at one of these resistors and you are feeding a signal into the "Main In" terminals, than the dropout is definitely in the amplifier for that channel. Get a good bias current reading and we'll go from there.

    - Pete
     

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