CCFL to LED Backlight Conversion - Backlight on when powered off.

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Lonfyre
    New Member
    • Oct 2016
    • 4
    • United States

    #1

    CCFL to LED Backlight Conversion - Backlight on when powered off.

    Well here's going to be an interesting one for a first post.

    I recently installed a CCFL to LED Conversion kit I picked up off eBay to repair a monitor found in my alley. After a few weeks of waiting for my brother's help to solder the wires to the PSU (integrated Inverter, AOC 22LVWk), I finally have the monitor working with a few quirks that I'd like to sort out and I'm looking for a little help in the right direction.

    1. When the monitor is "off" (always on power supply, no switch) the backlight turns on full blast and gives me a white screen.
    2. Brightness settings are odd. Below 30% is effectively monitor off, and going from 95 to 96 results in a sudden brightness spike. If you go over 96%, the screen starts making a whining sound.

    Originally with how it was originally wired, the backlight would turn off if the monitor had a signal, but I changed this by switching the ENA and DIM lines.

    The points we picked out to solder were found via the service manual (which includes schematics), but I feel we may be a bit off. Any advice that can point me in the right direction to solving this would be greatly appreciated.

    Points Soldered:
    -VIN is soldered to C823 positive terminal
    -GND is soldered to C823 negative terminal
    -DIM is soldered to P802 pin 7 (more accurately, soldered directly to the corresponding wire)
    -ENA is soldered to P802 pin 8 (like above, done due to issues with potentially bridging pins)

    eBay Link to LED Kit

    Service Manual on Docslide
    Last edited by Lonfyre; 12-18-2016, 02:08 AM. Reason: Additional Info Provided
  • Dumah Brazorf
    Senior Member
    • Jun 2013
    • 179
    • Italy

    #2
    Re: CCFL to LED Backlight Conversion - Backlight on when powered off.

    Originally posted by Lonfyre
    Originally with how it was originally wired, the backlight would turn off if the monitor had a signal, but I changed this by switching the ENA and DIM lines.
    ???

    Comment

    • stj
      Great Sage 齊天大聖
      • Dec 2009
      • 30953
      • Albion

      #3
      Re: CCFL to LED Backlight Conversion - Backlight on when powered off.

      upload the manual here & i'll help.

      Comment

      • Lonfyre
        New Member
        • Oct 2016
        • 4
        • United States

        #4
        Re: CCFL to LED Backlight Conversion - Backlight on when powered off.

        Originally posted by Dumah Brazorf
        ???
        On the instructions supplied in the eBay listing, ENA is listed as the backlight on/off and DIM is listed as the brightness control. With how we soldered the lines before hand, the backlight would be off the whole time. Swapped them in the connector to the controller/inverter supplied for the LED backlight and it suddenly worked.


        Originally posted by stj
        upload the manual here & i'll help.
        I've attached the service manual to this reply, and thank you very much for the help.
        Attached Files

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #5
          Re: CCFL to LED Backlight Conversion - Backlight on when powered off.

          Your dim control line of your monitor may be using PWM dimming instead of Analog dimming.
          Never stop learning
          Basic LCD TV and Monitor troubleshooting guides.
          http://www.badcaps.net/forum/showthr...956#post305956

          Voltage Regulator (LDO) testing:
          http://www.badcaps.net/forum/showthr...999#post300999

          Inverter testing using old CFL:
          http://www.badcaps.net/forum/showthr...er+testing+cfl

          Tear down pictures : Hit the ">" Show Albums and stories" on the left side
          http://s807.photobucket.com/user/budm/library/

          TV Factory reset codes listing:
          http://www.badcaps.net/forum/showthread.php?t=24809

          Comment

          • Lonfyre
            New Member
            • Oct 2016
            • 4
            • United States

            #6
            Re: CCFL to LED Backlight Conversion - Backlight on when powered off.

            I'm including an exact link to the kit I purchased, in hopes that it may be a little more helpful.

            Updated Link to exact kit purchased.

            Comment

            • stj
              Great Sage 齊天大聖
              • Dec 2009
              • 30953
              • Albion

              #7
              Re: CCFL to LED Backlight Conversion - Backlight on when powered off.

              remove L901 & L902 so you arent wasting power driving the unused invertor.

              your power points are good,

              leave the dim wire unconnected for now.
              so if i read right, the power signal was originally inverted. (lights on in standby, lights off when running)
              so try connecting your lights-on wire to pin1 of the OZ9936 lamp driver chip.

              Comment

              • rups
                New Member
                • Dec 2016
                • 2
                • china

                #8
                Re: CCFL to LED Backlight Conversion - Backlight on when powered off.

                LED Backlight Kit 這个套件亮度是反向控制的。

                Comment

                • rups
                  New Member
                  • Dec 2016
                  • 2
                  • china

                  #9
                  Re: CCFL to LED Backlight Conversion - Backlight on when powered off.

                  Df6113 databook
                  Attached Files

                  Comment

                  Related Topics

                  Collapse

                  • Document Archive
                    Design of CCFL Backlight Inverters with Frame & Bar Cores
                    by Document Archive
                    Design of CCFL Backlight Inverters with Frame & Bar Cores

                    Summary

                    Portable devices, such as notebook computers and personal digital assistants are developed rapidly nowadays, which places an increasing demand on display technology. The LCD with cold cathode fluorescent back lighting satisfies the requirements on display performance, size and efficiency.

                    The backlight inverter plays a crucial role in supplying the power to the lamps of these flat-panel displays.

                    The frame and bar ferrite cores, described in this brochure, are especially designed...
                    10-07-2024, 04:26 AM
                  • triplefour
                    UN65TU700DF picture and sound but no backlight. BL tests ok but repl. PSU didnt fix!
                    by triplefour
                    this tv is throwing me for a loop. do samsung tvs no longer have the backlight self test feature built into the power supply?
                    i tested the backlight with my LED tester and it lights up both strips. one of them reads 100v and the other reads 63.7v.
                    unplugged mainboard from power supply but left backlight plugged in, and then plugged psu wall power in. expected to see backlights light up but see nothing.
                    according to how ive diagnosed in the past, this would almost always be a bad power supply. replacement power supply was cheap like 20$ from ebay. but still i get not even...
                    09-13-2023, 10:43 PM
                  • ttmi100x
                    HANNSG Hi221 -- 2 secs to black feat. CCFL flicker & "burn" marks on power board
                    by ttmi100x
                    Greetings everyone,


                    I have a HANNSG Hi221 monitor that exhibits two seconds to black issues (backlight goes off, display is still on as confirmed by shining a flashlight on it) with some additional oddities...


                    The monitor failed on me with a standard "2 seconds to black" some time ago prompting me to initially replace most of the electrolytic capacitors (some of them were bulging/leaking).
                    Things kinda sorta worked for a night, then the problem returned along with some flickering and "buzzing" noises.

                    Upon closer inspection...
                    07-31-2024, 06:36 PM
                  • Comp_Pro
                    No Backlight Macbook A1990 820-01041
                    by Comp_Pro
                    Hello all,

                    Am trying to figure out this backlight issue with this A1990 Macbook Pro.

                    Tests performed:

                    There is no backlight even with a good screen.
                    Backlight IC is receiving the correct support voltages.
                    Fuse F8400 ok
                    Current sense resistor R8400 ok
                    Backlight IC is receiving 3.3V on enable pin.
                    Backlight IC receiving voltage from PPBUS_G3H, aprox 12.5V.
                    Backlight IC receiving 5V from PP5V_G3S
                    Backlight IC BKLT_SCL and BKLT_SDA both measure 0.545V diode mode to ground
                    I2C_BKLT_SCL and I2C_BKLT_SDA both measure...
                    05-06-2024, 10:23 PM
                  • DanPoka
                    Guide me through repairing a Dell p2210f LCD ccfl backlight monitor
                    by DanPoka
                    I bought this p2210f dell monitor to fix. Schematic is the same as p2210.
                    Behaviour is that monitors comes on but then backlight switches off almost instantly. If I look with flashlight I can still find the "No signal message". So definitely a backlight issue. Trying to advance the issue I proved that the protection circuit is switching off the backlight by shorting out C3 and resistor to disable the INL chip then re enable by removing the short.
                    This is where it gets interesting. When I disassembled the monitor to solder leads on c3 capacitor I noticed the backlight flickered...
                    02-15-2025, 05:05 AM
                  • Loading...
                  • No more items.
                  Working...