SANSUII BA-3000 PROBLEMS

Discussion in 'Exclusively Sansui' started by pppoffice, Aug 30, 2017.

  1. vigman

    vigman SUBSCRIBER

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    I guess my point here is it's good on the board, at the device so every bit down stream needs to match with minimal V loss.
    Under load it will turn to heat and go POOF!
     

     

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  2. pppoffice

    pppoffice AudioBear

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    The reason that the voltage on the pin marked -60V on the 2512 board is fed from the positive side of C-04 on the 2512 board whereas the first pin on the right opposite the 2508 board and the third pin where the bricks are mounted are alll DIRECTLY connected to the output of the 2508 board. There were no cold solder joints and the pins were squeaky clean.
     
  3. pppoffice

    pppoffice AudioBear

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    And I forgot to say that the voltages on the pins directly connecting to the 2508 board on the 2512 board were BOTH -67.6 VDC
     
  4. vigman

    vigman SUBSCRIBER

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    C-03 / 04 are still part of the unregulated +/- 68 volt PS.. I'm not understanding your point
     
  5. pppoffice

    pppoffice AudioBear

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    My point is that the spot where it is marked -60 does not directly lead to the pin coming out of the 2508 board nor either of the other two pins that do connect directly to the 2508 board. This spot marked -60 comes off of the positive side of C-04. The positive side of C-04 does not go directly to the same spot on the 2508 board where the other two pins do go. It just isn't a reading off of the same spot and it won't be exactly the same. I checked the other 2508 board and the same amount of difference in the negative voltages was there on that board too.
     
  6. vigman

    vigman SUBSCRIBER

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    Mike you said this...
    "The big caps were +62. 6 VDC and -62.4 VDC.
    The 65 volt section was +67.7 VDC on pin 3 and -62.5 VDC. "

    notice the 2 neg voltages are bang on.. i think you are taking the board ( 2512 ) measurements in the wrong place....
     

     

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  7. vigman

    vigman SUBSCRIBER

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    The traces marked +/- 60 lead back to the BIG CAPS and have NOTHING to do with the reg board...
     
  8. pppoffice

    pppoffice AudioBear

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    Mike, we have been taking voltages from all over the 2512 board. Sometimes you want the reading off of the pin opposite the 2508 board then sometimes you mention and show the third pin from the rignt over where the bricks get connected and then also the spot marked 60 (+_). What I am saying is that if I measure the negative voltage where it is marked -60 the reading will be different than if I measure dthe 60/65 volts on the pin directly on the other side of the 2508 board and the other pin that ISN"T marked 60. I guess I just don't know WHERE you want me to take the 60/65 volt readings from. You had said that there must be a problem because the voltage on the two pins that connect to the 2508 board were different and they really aren't. The difference is if I take that reading from where it is marked 60 on the 2512 board.
     
  9. pppoffice

    pppoffice AudioBear

    Messages:
    516
    Location:
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    Yes but that is where the board is marked +_ 60V.
     
  10. pppoffice

    pppoffice AudioBear

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    In a nut shell, the voltages from the pins that connect to the 2508 board are the same.
     
  11. pppoffice

    pppoffice AudioBear

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    I'm headed home for dinner. I should be back by about 18:30 hours.
     

     

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  12. vigman

    vigman SUBSCRIBER

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    Well there is no ACTUAL +/- 60... it's +/- 68 AKA the RAW unregulated power supply Like the +/- 85 that feeds the reg board input.
    When you measure the +/- 60 you are on the BIG CAPS....
    60 & 65 are NOT the same point....
    I will provide another mark up
     
  13. vigman

    vigman SUBSCRIBER

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    4,015
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    2512 #4 J.jpg
    Does this make things clear ( er ) ?
     
  14. pppoffice

    pppoffice AudioBear

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    Mike, I know where you are talking about the points/pins that are in direct contact with the 2508 board. I learned that only when you started asking me take voltage reading there. See if this makes sense to you from a novice point of view. When I take B+ or B- voltages I take them on the 2512 board where it is marked +85 and -85. When I take 35 volt readings I take them on the 2512 board where it is marked +35 and -35. When I take 60 volt readings I take them where it is marked on the 2512 board +60 and -60. I have been taking these voltage readings from these points on the 2512 board from the very beginning. Not until you started trying to figure out where the positive 65 volts was did you start having me take readings on pins that are NOT marked but instead are pins on the 2512 board that are directly connected to the 2508 board AND thru resistors on the 2508 board that go to TR-05 and TR-10. Can you now understand WHY I have been taking these voltages from the points/pins that I was taking the voltages. At least to me it is logical to think of taking these voltages from where they are clearly marked on the 2512 board. END OF SUBJECT!!
     
  15. vigman

    vigman SUBSCRIBER

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    MIke tell me the voltages you get with 2508#2 using the +/- 65 as outlined.
     
  16. pppoffice

    pppoffice AudioBear

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    In the future, if you will say where you want a voltage taken from, as you started doing when we were working on the 2508 board, I will be sure to take the voltage you want from the point/pin that you want the voltage taken.
     

     

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  17. pppoffice

    pppoffice AudioBear

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    I will head over to the shop and retake those readings. The last time I took them and gave them to you they were +67.6 and -67.6 VDC.
     
  18. vigman

    vigman SUBSCRIBER

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    Location:
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    You are correct TR-10 & 11 are tied directly to the +/- 68 volt rails, that is how the back half of the driver board is powered up.
     
  19. pppoffice

    pppoffice AudioBear

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    Location:
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    +67.569 VDC and -67.573 VDC.
     
  20. vigman

    vigman SUBSCRIBER

    Messages:
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    Location:
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    What I understood was this
    Mike you said this...
    TR-05 Emitter is +67.6 VDC. TR-10 Collector is -67.6 VDC. Voltage drop across ZD-01 is 14.62 VDC.
    THEN
    "The big caps were +62. 6 VDC and -62.4 VDC.
    The 65 volt section was +67.7 VDC on pin 3 and -62.5 VDC. "

    What you and I need to KNOW is all the voltages make it to the 2507 correctly.
    I want these amps to sing for you without smoke escaping.
    It is critical that we come to an understanding how this amp works, where to test & how to test.

    We did 3 full pages on this thread chasing something that in all probability was working.
    So I will be PAINFULLY precise from here on out
     

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