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DELL 2007FPB - black screen - power diode is green - backlight is purple/amber :)

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    #1

    DELL 2007FPB - black screen - power diode is green - backlight is purple/amber :)

    Hello everyone, i got, a problem with my LCD, suddenly the screen goes black one day and i'ts stay way . The backlight from specific angle is purple/amber ( hard to figure out which colour it is ), the power on diode is green, and everything seems ( i say seems ) to be ok. I just replaced all capacitors to new ones, measure the resistance of the tranformers, and they are like the new ones.

    One thing is strange but in electronic nothing is strange , that from lcd logic board ( the PCB attached to the LCD ), i hear strange noise from L1 ( 470 ) part, like it has some kind of short curcuit/transformer damaged noise. http://obrazki.elektroda.pl/7538632000_1346320971.jpg

    I had also measure voltage of that logic board, and measurements are extremely strange, and i do not know what causes that kind of abnormal readings :

    With power off, with power cable attached :

    VGH - 3,3V
    VGL - 0V
    VGM - ?
    VLCD - 0
    VCC - 0
    VIN - 1,8 and it falls

    With power on with power cable attached :

    VGH - 0,13V
    VGL - 4,1V
    VGM - ?
    VLCD - 4,99V
    VCC - 8,34V
    VIN - 18,37V

    If anyone got some kind of tip to direct me what do i have to chedck and what o have to replace to be able to work in frony of my LCD, i will be appreciated.

    Best regards

    Thomas

    The other photos of inside of that LCD :

    http://obrazki.elektroda.pl/6251092200_1346320973.jpg
    http://obrazki.elektroda.pl/3115375600_1346359505.jpg
    http://obrazki.elektroda.pl/1209913500_1346359507.jpg
    http://obrazki.elektroda.pl/3416521700_1346359509.jpg
    http://obrazki.elektroda.pl/3513090000_1346359511.jpg
    http://obrazki.elektroda.pl/5415896500_1346359513.jpg
    http://obrazki.elektroda.pl/2920540900_1346359515.jpg
    http://obrazki.elektroda.pl/2419529000_1346359517.jpg
    Tags: None
    #2
    Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

    1) Follow my instructions below exactly on how we want pictures posted.

    2) See

    https://www.badcaps.net/forum/showthread.php?t=20531
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      #3
      Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

      Hello, again here are the better quality photos :





      Attached Files

      Comment

        #4
        Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

        Originally posted by madfreak View Post
        Hello everyone, i got, a problem with my LCD, suddenly the screen goes black one day and i'ts stay way
        If you plug in a computer displaying your favourite wallpaper, does the image come on briefly and then disappear?
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          #5
          Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

          Originally posted by retiredcaps View Post
          If you plug in a computer displaying your favourite wallpaper, does the image come on briefly and then disappear?

          Hi the backlight from specific angle is purple/amber. But to be less specific it's black, all the time, and it do not show the osd menu and etc.

          Comment

            #6
            Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

            Originally posted by madfreak View Post
            it's black, all the time
            Okay, if the backlight does not come on at all and the power LED is green, then the problem is likely in the inverter section. I circled 6 mosfets which I believe are SP8M3.

            http://pdf1.alldatasheet.net/datashe...OHM/SP8M3.html

            If correct, test to see if the 6 mosfets are shorted or not following the procedures in my guide (section mosfets)

            https://www.badcaps.net/forum/showpo...4&postcount=19

            Note to tom66 and selldoor. If you are wondering, how the heck could I read that given the OP's photo, I have the exact same monitor in my "to do" pile and am reading my inverter board with a 10x loupe.
            Attached Files
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              #7
              Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

              Hello, in first i want to thank You for trying to help .

              I am just after measurments of those mosfets, and they do not have shorten pins.

              But what i had notice, after Your tip i measure other parts, and. in picture that i attached i point 2 eeproms.

              The 1 eeprom have a shorted pins 1/2, 1/3, and 2/3, i compare those measurments to the 2nd eeprom that i circled which is i think good.

              Tell me if it is possible that this eeprom chip is really damaged ? And what i have to do to replace it, and because it's an eeprom memory so i have to after replacing it flash it i think but i can be wrong.



              Cheers

              Thomas
              Attached Files

              Comment

                #8
                Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                Hello, in first i want to thank You for trying to help .

                I am just after measurments of those mosfets, and they do not have shorten pins.

                But what i had notice, after Your tip i measure other parts, and. in picture that i attached i point 2 eeproms.

                The 1 eeprom have a shorted pins 1/2, 1/3, and 2/3, i compare those measurments to the 2nd eeprom that i circled which is i think good.

                Tell me if it is possible that this eeprom chip is really damaged ? And what i have to do to replace it, and because it's an eeprom memory so i have to after replacing it flash it i think but i can be wrong.

                1st one : ST 24C02RP ( in bottom line K823G )
                2nd one : 25x40VN1G ( in bottom line 0821 )



                Cheers

                Thomas
                Attached Files
                Last edited by madfreak; 09-06-2012, 04:45 AM.

                Comment

                  #9
                  Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                  Originally posted by madfreak View Post
                  The 1 eeprom have a shorted pins 1/2, 1/3, and 2/3, i compare those measurments to the 2nd eeprom that i circled which is i think good.

                  Tell me if it is possible that this eeprom chip is really damaged ? And what i have to do to replace it, and because it's an eeprom memory so i have to after replacing it flash it i think but i can be wrong.

                  1st one : ST 24C02RP ( in bottom line K823G )
                  2nd one : 25x40VN1G ( in bottom line 0821 )
                  1) When comparing two totally different part numbers, you cannot assume they have the same pinouts.

                  2) If you look at the datasheets, you will notice that.

                  http://pdf1.alldatasheet.net/datashe...25X40VDAC.html

                  http://pdf1.alldatasheet.net/datashe...4C02RB1TR.html

                  3) For ST 24C02RP, pins 1, 2 and 3 are the chip enable inputs. If you look at figure 1 on the datasheet, it looks like they are supposed to be shorted together.

                  4) Now it is possible that the eeprom is corrupted which is causing your problem, but I have no way of testing that. The one possibilty might be to dump the eeprom and compare it with a known good eeprom, but that is beyond my skills and patience level.
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                  Comment

                    #10
                    Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                    1) On the inverter board, the pwm chip is OZ946GN (at least on mine).

                    http://pdf1.alldatasheet.com/datashe...2/OZ964GN.html

                    2) Refer to the datasheet for pinouts.

                    3) Pin 6 is GND.

                    4) What are the DC voltages for the other 19 pins using pin 6 as GND (or a ground screw)? List them all like so

                    pin 1 = 1.234
                    pin 2 = 0.003
                    etc

                    5) You will need steady hands on such a closely packed IC because you don't want to short out the component.
                    Last edited by retiredcaps; 09-06-2012, 05:46 PM.
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                      #11
                      Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                      I am curious, what do you see on the back and on the front of the panel when look at it in a dark room?
                      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

                        #12
                        Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                        Ok . After 1,5 h of tries to solder thin wire to 6 PIN, i finally did it . (safety first ).

                        Here are my measurments :

                        PIN 1 - that is strange pin i got different readings, first when i push power on button and connect to that pin multimeter it shows 1.8V and it drops slowly to 1.6V, then after some time ( for ex. 1 minute ), it shows 2.5V and it show it all the time

                        PIN 2 - 0.63V-065V

                        PIN 3 - 2.56V

                        PIN 4 - 4.86V

                        PIN 5 - 5.16V

                        PIN 7 - 3.23V

                        PIN 8 - 0.56V

                        PIN 9 - 1.2V

                        PIN 10 - 1.45V

                        PIN 11 - 2V

                        PIN 12 - 2.63V

                        PIN 13 - 1.5V

                        PIN 14 - 1.39V

                        PIN 15 - 1.15V

                        PIN 16 - 0V

                        PIN 17 - 0V

                        PIN 18 - 0V

                        PIN 19 - 2.61V

                        PIN 20 - 2.02V


                        If that chip is damaged i will be so happy, because it's cheap as hell , but i think that it will not be so easy .

                        Cheers

                        Thomas
                        Last edited by madfreak; 09-06-2012, 11:23 PM.

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                          #13
                          Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                          I am curious, what do you see on the back and on the front of the panel when look at it in a dark room?
                          I see that the backlight is on because light is coming from back of the lcd, but screen is violet/amber/purple its some kind of combination of those colours ( it's one color but it's hard to figure out which tone )

                          Comment

                            #14
                            Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                            Originally posted by madfreak View Post
                            PIN 3 - 2.56V
                            From a quick cursory glance, the pwm chip is working correctly given the voltage readings above. Pin 3 is enable and the pwm chip is "ON" when the voltage is greater than 2V.
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                              #15
                              Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                              Maybe it is important, but after playing of source button, i change the source from 1-4, and...

                              on source 1 and 2 the lcd acts the same way purple-ish screen, but when i change it to 3 or 4 its shutting down the backlight and the screen is completely black ( just like the famous "2 sec to black" ).

                              Comment

                                #16
                                Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                                U8 is a voltage regulator on the t-con or panel board.

                                Test it and report your results and the part number of it.
                                Last edited by retiredcaps; 09-06-2012, 11:44 PM.
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                                  #17
                                  Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                                  I got such a bad eye sight , from those whole years in front of computer. U8 is on back of that board with DVI, VGA etc ports ?

                                  It is 8 PIN. - ATMLH810

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                                    #18
                                    Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                                    See attached picture.
                                    Attached Files
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                                      #19
                                      Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                                      Part number RT9164A in bottom line 18GLAHU04

                                      From top to bottom as it is on that picture.

                                      PIN 1 - 0.83V - 0.84V

                                      PIN 2 - 0.67V - 0.68V

                                      PIN 3 - 0V
                                      Last edited by madfreak; 09-07-2012, 12:18 AM.

                                      Comment

                                        #20
                                        Re: DELL 2007FPB - black screen - power diode is green - backlight is purple/amber

                                        It seems like it is the problem, am i thinking correct ?

                                        It should show me 1.8V not those small measures ?
                                        Last edited by madfreak; 09-07-2012, 12:24 AM.

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