Sansui G7000 tuner problem

Discussion in 'Exclusively Sansui' started by anderslober, Mar 31, 2018.

  1. anderslober

    anderslober Yikes...not again! Subscriber

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    Hi again Forum,
    I have a g7k here that needed a total recap. All is done, except the big caps...they will have to go too.

    Anyway.....as always the darn tuner is giving me a hard time...all voltages are fine. Tuner is recapped. All caps orientation double checked and rechecked.

    It can tune.....but reluctantly. When I put my finger on TP1 and tune......everything is normal...stereo light comes on....signal meter works....all is good. When I remove my finger from TP1.....signal meter goes dead and stereo light doesnt work...and there is only sound if FM mute is OFF.

    I have not touched anything on the tuner except the caps. The frontend is absolutely filthy with nicotine...

    Any good ideas
     

     

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  2. anderslober

    anderslober Yikes...not again! Subscriber

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    I have bought some big cans....NCC....screw mount....but they came with no screws!:-( What size is standard...m5...m6?......8mm long...? Thanks...
     
  3. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    I think you will have to find this out by trial and error, as it could be anything around those sizes. Measure the depth of the screw hole carefully - then you'll have the length. Then try known screw sizes in the threads which should screw in with fingers only (i.e. no forcing) - until you find one that fits perfectly. :) This is of course unless you know someone with some thread gauges, who should be able find out almost immediately, no matter what the thread size is. ;)
     
  4. anderslober

    anderslober Yikes...not again! Subscriber

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    John...how are ya`? I wont be needing the nice caps that I bought....because the g7k has friggin` dual caps. I have do make a construct now.........

    The unit has low-level hum, independent of volume......so I think the big caps have to go. I have checked all grounding.....and its fine.

    Any ideas on the tuner issue? Tuner works fine...IF my finger or a probe is on TP1......
     
    Last edited: Mar 31, 2018
  5. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Not really, sounds like it could be an adjustment, but what exactly I couldn't say - the changed electrolytics could have altered many settings.
     
  6. Kale

    Kale Super Member

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    I think that 3sk41 is bad.... and about restoring dual caps, please look at my web site, article "Sansui G701 Receiver"... there you will find interesting pictures about restoring G701 (G7000), and how I did restoration on main dual-caps.
     
    Last edited: Mar 31, 2018
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  7. anderslober

    anderslober Yikes...not again! Subscriber

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    Kale...whats the link to your website?
     
  8. Kale

    Kale Super Member

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    Please look at inbox of your PM
     
  9. anderslober

    anderslober Yikes...not again! Subscriber

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    3sk41....any subs?
     
  10. anderslober

    anderslober Yikes...not again! Subscriber

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    Woooowwww Kale......amazing work by you, as usual! I will attempt your method....
     
  11. kevzep

    kevzep Its all about the Music Subscriber

    Anders!! Great to see you here again.

    Yes I agree with Kale that the FET will be bad, and you are able to get it working again by loading it down with your finger.

    I do not think it will be an adjustment, of all the tuners I have aligned, which is quite a lot now, the IF adjustment is normally very good, unless someone has been in there fiddling.
    Even if its off a bit, it will not have as dramatic effect as you are having.

    I have a G7000 on the bench with a Tuner fault as well. If you wouldn't mind, would you be able take a voltage reading on Pin 11 and Pin 12, (orange and red), they are right at the front of that tuner board. (front of the G7000).
    Also could you take a picture of the termination of Pin 11 and 12 on the Copper Track side of the board.
    This one I have here is a mess.....
    I'd really appreciate if you could do that.

    I'll look up a sub for the 3SK41 in the meantime.

    Also, did you replace the four 100Ω resistors on the EQ board which are in line with the +/- DC supplies? They are fusible and go hiΩ which stops the Phono inputs working.
     

     

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  12. kevzep

    kevzep Its all about the Music Subscriber

    Anders, there are some NOS 3SK41's on the Bay at the moment, they are in the US, and I believe they will probably be the real article. Still got 7 available....
     
  13. anderslober

    anderslober Yikes...not again! Subscriber

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    Hey Kevin.....yes....I can do that. Tomorrow. Its night now here in Denmark...

    I will get a new FET....I hope its just that.

    Yes..I definitely replaced the 4 fusibles on the EQ board.

    Next will be a big can operation like Kale`s.
     
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  14. dr*audio

    dr*audio Fish fingers and custard!

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    Be sure to take antistatic precautions when replacing that mosfet! Wear a grounded wrist strap, short the pins together with a wire if possible, until it is soldered in. If not possible to short the pins, solder the Source, then Drains then Gates.
     
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  15. kevzep

    kevzep Its all about the Music Subscriber

    Excellent advice Warren!!
     
  16. anderslober

    anderslober Yikes...not again! Subscriber

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    Antistatic band..check. Darn expensive those 3sk41´s!

    Kale....how did you `glue` the new caps in the cans?
     

     

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  17. anderslober

    anderslober Yikes...not again! Subscriber

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    B8E09D87-6681-4552-9522-1F1487311882.jpeg Kevin....Pin11 and Pin12 are co-connected by the same red wire. I have 12.5vdc. Both pins of course.
     
  18. anderslober

    anderslober Yikes...not again! Subscriber

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    Kevin...trace side of pin11/12....enjoy. Original config...no changes from me at all. DC915E86-5FE1-4A29-AD32-1A35C1A02CBA.jpeg
     
  19. Kale

    Kale Super Member

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    With just few dots of silicone glue for electronic....

    I am going to put pictures of restoring dual caps here...

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  20. kevzep

    kevzep Its all about the Music Subscriber

    Thanks Anders,I really appreciate you taking the time to do that for me, interesting, your one is a bit different than the one I have here, but it did tell me what I need to know...
    Mine had the main tuning capacitor trimmer caps shorting out on the shield that surrounds it....
    That was tricky to find...
    Then we have this situation where the tuning is out by about 6mhz, cant adjust it down, so now I have to chase this fault around .....
    Fun fun fun!!

    I like the way Kale did those multi-caps, very impressive.....
     

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