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Monitor Benq Q7T$

Discussion in 'Datasheets, Manuals and Component Identification' started by newton, May 30, 2010.

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  1. newton

    newton

    5
    0
    May 18, 2010
    Hello,
    Pls.
    I would need the electrical schematic of this monitor:
    Benq Q7T4
    someone can help me?
    Thanks
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,500
    2,840
    Jan 21, 2010
    Google tells me it's here.

    Incidentally, this appears to be the same monitor as the one I used for a "trial run" of replacing the CCFL tube on my laptop (which I have now completed -Yay).

    One thing I'd be aware of is that the various generations of the device have slightly different methods of attaching the plastic cover. The manuals almost always show screws and the back just lifting off. In my case there were no screws, just plastic clips.

    If you have one with the plastic clips, the best way of opening them up without damaging the housing is to cut small pieces of stiff thin plastic (I used pieces from a soft-drink bottle) and slip them in between the bezel and the back cover. The clips pop open and you can slide the pieces of plastic around to remove the rear cover. You need a couple of the bits of plastic to prevent the clips from snapping back as you start.

    edit: It's also interesting to note that there appear to be several common faults with these monitors (according to google). It may be that they're just very common, but either way, you may find that your fault is mentioned along with the fix. (What is the fault?)
     
    Last edited: May 31, 2010
  3. newton

    newton

    5
    0
    May 18, 2010
    Thanks for the service manual and the instructions provided
    The problem with this monitor is as follows:
    after I press the power button lights come on for a few seconds and then go off immediately.
    Now run the controls and after I tell you...
    Thanks
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,500
    2,840
    Jan 21, 2010
    There is a fault reported where dry joints on the inverter board and capacitor failure lead to one or more transistors failing. Apparently it gives the power on for a few seconds then off symptom.

    I read this whilst looking for the manual, so take it with a grain of salt. Google a bit and you may find someone who's repaired one with the same symptoms. It may save you some fault-finding effort.
     
  5. newton

    newton

    5
    0
    May 18, 2010
    Hello Steve,
    I did some checking and found the following components broken:

    - Fuse PF801 (3A, 125V) open
    - Q805, Q812 (Mosfet IRFU 9024AN) shortcircuited
    - Q808, Q809, Q815, Q816 (2SC5707) shortcircuited

    I solved the problem by changing all the components of the list above.

    Warning: You must make new welds on C824, C826 (0.22uF 160V), otherwise the fuse (PF801) would open new.
    Thanks
     
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