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BD 701s Convergence Output Failure Points?

Discussion in 'Projectors, Screens & Video Processors' started by krasle, Jan 14, 2005.

  1. krasle

    krasle
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    Hi,

    I have 2 BD 701s projectors, both of which are faulty.
    Up until last week, my main BD 701s had been working rather well.
    The convergence was not what it used to be and seemed to drift a
    bit. Last week, the unit stopped working. When I power the unit
    on, all the leds on the front panel flash on and off and it sounds
    like it tries to turn on repeatedly, but fails. I happen to have
    a second BD 701s and the service manual as well. The second 701s
    has a problem, in which all the green leds come on, but the orange
    led also comes on and I get no picture.

    By swapping out boards, I was able to determine that swapping the
    Convergence Module (OUTPUT) R762455 would also swap the two problems
    I described. It would seem that the problem with both projectors is
    this board. I think using the service manual, I can identify the
    parts well enough,and I wanted to try replacing the most likely sources
    of failure. I was hoping someone could give me some guidance as
    to which components I are the most likely to be failing so that I
    can try replacing them. The best I could find on the internet was
    that possibly the zener diodes may be bad.

    Additionally, I have a 40 MHz 2-channel oscilliscope That I could
    use to check any signals on the board. Unfortunately, the service
    manual does not give a lot of guidance for troubleshooting. Are there
    any points I might check to better determine where the failure is?

    Any help would be much appreciated.

    Regards,

    Darin Krasle
    krasle hotmail.com
     
  2. joflo

    joflo
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    Hi,

    i have some troubles myself with this board.
    It is difficult to identify the broken channel as it is protecting and cut-off the power what it is a good thing :)

    In my case was the green OPAMP.I would go changing first all three OPAMP - TOxxx and then i will take the second step - for the board it's causing flashing.

    2nd step after reparing the fault i replaced all active parts and capacitors - my god what a stability on convergence.

    What version do you have all MOSFET or transistor + MOSFET?

    Joflo
     
  3. krasle

    krasle
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    Hi Joflo,

    It sounds like a place to start now. Replacing all the active parts must have
    gotten pretty expensive, huh? My board would appear to have transistors and
    MOSFETs in the driver stage. I haven't checked the numbers, but I assume the
    8-pin DIP packages (chips) near the connectors are the opamps. Did you
    incrementally test the board, or just after swapping the components? Do you
    think the drift was in the active components or the capacitors?

    Thanks for your answer,

    Regrads,

    Darin Krasle
    Regards
     
  4. joflo

    joflo
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    ~ 70 Euro to change the essential.

    There are some components i was unable to find , but it did not matter.

    If you want more details PM, because the matter will becam technical and i do not hink peoples are very interested.

    BR,
    Joflo
     

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