Shorted 6060

Discussion in 'Exclusively Sansui' started by rotco, Jun 14, 2018.

  1. rotco

    rotco Member

    Messages:
    76
    Hi everyone
    please, i need your help with this one.
    i will say first that i'm an amateur, but have basic knowledge and experience which i got mostly from you guys.

    i just done cleaning and maintaining Sansui 6060 which was work absolutely fine.
    as last step, i just wanted do to the Bias adjustment as described in the S.M
    Mistakenly, while touching the resistors leads with the DMM probes, i also touched the chassis and then the two fuses got burned. (F603, F602) (250V, 5A)
    1. While the fuses are off from the board, i turned on the receiver, it powered on, but the protection relay didn't "click".

    I hope tomorrow i will find new fuses in the store,
    but i really think that something went bad and the new fuses will auto-burned while i will turn the receiver ON.

    I have a Dim Bulb Tester, i will use it. if i will find the receiver is shorted, which test can i make in order to find which components got died?

    thanks

    B.T.W is there any chance that nothing got damaged and if i'll put new fuses the receiver will play again?
     

     

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  2. Tom B

    Tom B AK Subscriber Subscriber

    Messages:
    1,345
    Location:
    Bay Ridge, Brooklyn New York
    While I would hope that all will be fine after replacing the fuses, in reality those 2 fuses are the ones supplying primary DC to the output transistors and driver board. They usually pop when output transistors short.
     
  3. rotco

    rotco Member

    Messages:
    76
    Unfurtunatly, i couldn't hold my self andwait to get new fuses, i was so curious if something went wrong or maybe everything just fine exept the fuses themselfs.

    So, i wrapped the fuses with aluminium foil, and powered ON the receiver thru a Dim Bulb Tester with 60W lamp in series. (My wall power system is 220v)

    It turned ON, but after about 10 seconds or less i notice a SMOKE! (I know i did stupid thing) and i turned it OFF immedietly.
    The smoke raised from the middle area of the vertical board (F-2647)
    I couldnt notice exactly where from, and couldnt notice burn smell from specific area or see a signs of black "burn" spot.

    I feel really lost..

    What do i need to do?
    Start by tacking off the output transistors and check them? If they are shorted, replace and hope that will solve the issue?
     
  4. Tom B

    Tom B AK Subscriber Subscriber

    Messages:
    1,345
    Location:
    Bay Ridge, Brooklyn New York
    Foil wrapping fuses, as you found, was the worst thing you could have done. You probably had shorted outputs, and now you may have a number of other components bad.
    I would suggest you find a good component level technician familiar with vintage gear to fix your unit.
     
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  5. rotco

    rotco Member

    Messages:
    76
    But!!
    I used a DBT!
    I thought it should protecting me!
    Limit the current... And in any case i have a short.. So.. What could have happen?
    The current will move thru the short and nothing bad will happen!
    Thst what i thought.. At least..
    My only suspect is.. That there was no short.. And while i used the aluminium foil.. Then i couse one to happen!
    But.. Again.. Why the DBT didnt saved me in that case?!
     
  6. rotco

    rotco Member

    Messages:
    76
    Hi guys

    i came back working on this receiver.
    i installed new 5A fuses and connect it thru DBT, i've got short (Light bulb was fully ON).
    so i disassemble the Driver circuit board (F-2647) and now i haven't got short (Light bulb was almost OFF)
    not sure if i can conclude from it that the culprit is in the F-2647 board ( i wish cause it's a simple board),
    but for some guess I mostly suspect the four (output) TO-3 transistors.

    i rather take measurements on live, rather than take them off the board and check them outside.
    maybe someone can help me determine the correct voltages on their leads to verify?

    or maybe you recommend to take them out and check if they are shorted?

    Thanks sansui 6060 F-2648 schematics.JPG sansui 6060 F-2648 diagram.JPG sansui 6060 output transistors.JPG
     

     

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