need help with a gateway lp2407/fpd2484

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  • chetreynolds
    chet
    • Aug 2010
    • 77

    #1

    need help with a gateway lp2407/fpd2484

    I have a gateway lcd that will not turn on . I have 135vdc at the filter cap .The esr values on all caps are ok to insure no parallel I removed the caps for measurment . I have inspected the circuit boards with an eye loop and found no bad joints . It has a switchless control does anyone know how to check this switch or bypass it on the main board /
  • PlainBill
    Badcaps Legend
    • Feb 2009
    • 7034
    • USA

    #2
    Re: need help with a gateway lp2407/fpd2484

    Originally posted by chetreynolds
    I have a gateway lcd that will not turn on . I have 135vdc at the filter cap .The esr values on all caps are ok to insure no parallel I removed the caps for measurment . I have inspected the circuit boards with an eye loop and found no bad joints . It has a switchless control does anyone know how to check this switch or bypass it on the main board /
    Define 'turn on'. Is the power supply producing normal voltages? As far as the switch, usually it is monitored by a processor on the signal card.

    Note my signature. Assisting without benefit of adequate pictures is difficult.

    PlainBill
    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

    Comment

    • chetreynolds
      chet
      • Aug 2010
      • 77

      #3
      Re: need help with a gateway lp2407/fpd2484

      there are no indicator lights the only voltage that I can check is the raw input voltage which is 135vdc . Trust me pictures will not help I have examined every connection with an eye loop and removed every cap and measured its esr all are less than .5 ohms . I suspect that there is no on signal from the front panel but I dont know howm to test it . It is a switchless device.

      Comment

      • pedro
        Senior Member
        • Dec 2009
        • 199
        • AUSTRALIA

        #4
        Re: need help with a gateway lp2407/fpd2484

        Originally posted by chetreynolds
        I have a gateway lcd that will not turn on . I have 135vdc at the filter cap./
        That is not right unless your line voltage is about 95V AC. It *may* indicate a failed diode in the main bridge rectifier. Unless/until the DC voltage across the main (filter) cap is correct I wouldn't be looking further downstream. Others may see this differently.
        Friends don't let friends buy Samsung ....

        Comment

        • PlainBill
          Badcaps Legend
          • Feb 2009
          • 7034
          • USA

          #5
          Re: need help with a gateway lp2407/fpd2484

          Originally posted by chetreynolds
          there are no indicator lights the only voltage that I can check is the raw input voltage which is 135vdc . Trust me pictures will not help I have examined every connection with an eye loop and removed every cap and measured its esr all are less than .5 ohms . I suspect that there is no on signal from the front panel but I dont know howm to test it . It is a switchless device.
          The power supply is always on - or at least the 5V standby portion.

          But since you know more than I do, fix it yourself.

          By the way, you should be asking yourself why the input voltage is 135VDC.

          PlainBill
          For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

          Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

          Comment

          • chetreynolds
            chet
            • Aug 2010
            • 77

            #6
            Re: need help with a gateway lp2407/fpd2484

            sorry if I offended you .

            Comment

            • jetadm123
              Badcaps Legend
              • Feb 2010
              • 2169

              #7
              Re: need help with a gateway lp2407/fpd2484

              I think one of the main problems here is lack of photos. You may think they are unimportant, but since we're not sitting next to you or looking over your shoulder, it's hard to follow what's going on. Members need good focused photos to suggest what components to test. And they need to see photos of YOUR boards, since there are probably different revisions/configurations out there. And finally, I agree with pedro and PlainBill that the 135V across the main cap is a problem.

              Comment

              • PlainBill
                Badcaps Legend
                • Feb 2009
                • 7034
                • USA

                #8
                Re: need help with a gateway lp2407/fpd2484

                Originally posted by chetreynolds
                sorry if I offended you .
                Let me explain my insistence on pictures. First of all, Gateway does not build these monitors; rather they are designed and built by one or more companies in China. As a result an FPD2484 can have one of several different power supplies, LCD panels, and even signal cards. Telling someone to measure the voltage across C10 (start up capacitor in one design) would be meaningless if in his version C10 was a line noise suppression cap.

                Even in the case of a single power supply, I would have to first locate a picture of the power supply (schematics are very hard to come by for Gateway products), then identify the critical points to measure.

                PlainBill
                For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                Comment

                • retiredcaps
                  Badcaps Legend
                  • Apr 2010
                  • 9271

                  #9
                  Re: need help with a gateway lp2407/fpd2484

                  If you are in the USA, your mains are 120V AC. Voltage across the main filter capacitor is 120V AC x 1.414 = roughly 165V DC.

                  0.5 ohms ESR depending on the uF, voltage, diameter, and height of the cap can by too high.

                  For example, a Panasonic FR 1000uF 25V cap has an ESR of 0.018 ohms according to

                  http://search.digikey.com/scripts/Dk...name=P14425-ND
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                  Comment

                  • chetreynolds
                    chet
                    • Aug 2010
                    • 77

                    #10
                    Re: need help with a gateway lp2407/fpd2484

                    The voltage at the filter cap was a typo it is 185vdc .I rechecked the esr readings of the caps and all read 0 ohms with my .
                    Attached Files

                    Comment

                    • retiredcaps
                      Badcaps Legend
                      • Apr 2010
                      • 9271

                      #11
                      Re: need help with a gateway lp2407/fpd2484

                      Originally posted by chetreynolds
                      I rechecked the esr readings of the caps and all read 0 ohms
                      What type of ESR meter do you have?
                      Last edited by retiredcaps; 02-15-2011, 01:40 PM.
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                      If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                      We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                      Please do not post inline and offsite as they slow down the loading of pages.

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                      Comment

                      • chetreynolds
                        chet
                        • Aug 2010
                        • 77

                        #12
                        Re: need help with a gateway lp2407/fpd2484

                        it is a homemade meter made from instructions from http://ludens.cl .

                        Comment

                        • retiredcaps
                          Badcaps Legend
                          • Apr 2010
                          • 9271

                          #13
                          Re: need help with a gateway lp2407/fpd2484

                          Originally posted by chetreynolds
                          The voltage at the filter cap was a typo it is 185vdc .
                          Hmm, I think I deleted my response by mistake.

                          Is that 185V DC? If yes, it still seems off from the traditional 165V DC.
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                          If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                          We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                          Please do not post inline and offsite as they slow down the loading of pages.

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                          Comment

                          • chetreynolds
                            chet
                            • Aug 2010
                            • 77

                            #14
                            Re: need help with a gateway lp2407/fpd2484

                            Its 185 but I am using an isolation transformer that 133vac out

                            Comment

                            • jetadm123
                              Badcaps Legend
                              • Feb 2010
                              • 2169

                              #15
                              Re: need help with a gateway lp2407/fpd2484

                              Disregard

                              Comment

                              • PlainBill
                                Badcaps Legend
                                • Feb 2009
                                • 7034
                                • USA

                                #16
                                Re: need help with a gateway lp2407/fpd2484

                                Originally posted by chetreynolds
                                Its 185 but I am using an isolation transformer that 133vac out
                                That explains the voltage. The isolation transformer is a nice touch, wish I could find mine (how can someone lose an isolation transformer?)

                                I'd like a picture of the daughter board if possible. I realize that's pretty cramped. What is the part number of the IC?

                                PlainBill
                                For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                                Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                                Comment

                                • chetreynolds
                                  chet
                                  • Aug 2010
                                  • 77

                                  #17
                                  Re: need help with a gateway lp2407/fpd2484

                                  The chip is
                                  synapac
                                  t1007 0541
                                  amn371-12
                                  The sharing of your expertize is greatly appreciated . My wife has malcurlar degeneration and this large screen would be a great help for her ,
                                  Attached Files

                                  Comment

                                  • PlainBill
                                    Badcaps Legend
                                    • Feb 2009
                                    • 7034
                                    • USA

                                    #18
                                    Re: need help with a gateway lp2407/fpd2484

                                    Originally posted by chetreynolds
                                    The chip is
                                    synapac
                                    t1007 0541
                                    amn371-12
                                    The sharing of your expertize is greatly appreciated . My wife has malcurlar degeneration and this large screen would be a great help for her ,
                                    Sorry, I wasn't clear. The daughter board is the board mounted vertically on the main power supply. That contains the SMPS controller, which is the next area to be investigated.

                                    PlainBill
                                    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                                    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                                    Comment

                                    • chetreynolds
                                      chet
                                      • Aug 2010
                                      • 77

                                      #19
                                      Re: need help with a gateway lp2407/fpd2484

                                      I should have known I seem to be fixated on the power switch because I have no clue on how to test it .
                                      I made a stupid mistake when unsoldering the board after hearing 3 load pops I reliazed that I forgot unplug the power and dischard the filter cap I may be getting to old for this . I cant see any burnt areas are cracked parts so maybe the is no uncoverable damage .
                                      Attached Files

                                      Comment

                                      • darnwalls005
                                        New Member
                                        • Feb 2011
                                        • 2

                                        #20
                                        need help with a gateway lp2407/fpd2484

                                        i also need help with a gateway lp2407. the diode at marker d851 on the main power supply board got burnt out and was trying to identify the specifications on it so i can replace it

                                        i cropped a picture of the diode in question
                                        Attached Files

                                        Comment

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