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    HP L1740 Lcd inverter/power board

    I have four HP L1740 monitors that have failed recently. Each has the same problem. Powers up normally, displays (windows desktop) for a couple of seconds and then goes black. I have diassembled three of monitors all three inverter/power boards have blown caps. I am going to order the following caps from mouser.com:
    470 uf 50V, 140-ESRL50V470-RC (XICON)
    1000 uf 50V, 661-EKY500ELL102MM2 (UNITED CHEMICON).
    2200 uf 25V, 647-UPW1E222MHD3 (NICHICON)
    1000uf 16V, 647-UPJQC102MPD (NICHICON)
    1000uf 25V, 647-UPM1E102MHD (NICHICON)

    The inverter/power board p/n is T50P062.00 Rev:2 I have been trying to find any information on these boards, assembly, schematics, etc. Also this is my first attempt at repairing these monitors. If I can repair them, 2 of the 4 monitors are mine to keep. The other two are for company spares.
    Hope I am on the right track in replacing these blown caps.
    thanks,
    George

    #2
    Re: HP L1740 Lcd inverter/power board

    Welcome George!

    Original caps brand, series, & dimensions (DxH in mm), please. HOw many of each value? What is max height you can go?

    Pics are always a plus!

    I question a couple of the choices, but I'd need to see the originals info first. The PJ is a General Purpose cap and the ESR on a few looks a touch too high.

    Also, resolder the transformers at all pins and check the C5707 transistors. Any heat damage or discoloration of the board around them would make them suspect.

    Toast
    Last edited by Toasty; 10-28-2009, 04:29 PM.
    veritas odium parit

    Comment


      #3
      Re: HP L1740 Lcd inverter/power board

      All capacitors are CapXon:
      470uf 25V 10mm x 9mm (3 each)
      2200uf 10V 10mm x 12mm (2 each)
      1000uf 25V 15mm x 12mm (1 each)
      1000uf 10V 10mm x 9mm (1 each)
      1000uf 6.3V 8mm x 9mm (1 each)

      I think there is only 1 Transistor on here and checked for shorts, none found.
      don't have digital camera right now so no pictures at the moment.
      thanks.

      Any recommendations on replacement caps would be very helpful.
      I am going to order enough capacitors to repair the four inverter/power
      boards. Also any info on who makes these invertors????
      Last edited by George Ortiz; 10-28-2009, 05:17 PM.

      Comment


        #4
        Re: HP L1740 Lcd inverter/power board

        Series is on the side opposite the values. Right near the temperature markings. Similar looking to this:

        KF 105°C -or- KM(M) 105°C

        KF & KM would be the series.

        Toast

        EDIT: Inverters are made by several. Usually marked on the board. FSP is one maker.
        Last edited by Toasty; 10-28-2009, 05:37 PM.
        veritas odium parit

        Comment


          #5
          Re: HP L1740 Lcd inverter/power board

          Toasty all caps are KF 105 C......

          Comment


            #6
            Re: HP L1740 Lcd inverter/power board

            Your dimensions don't match the Capxon data sheet. If you are in the USA I suggest Digikey. All of the following match the Capxon dimensions and are in stock. They will ship the following order for under $3.00 via first class mail.

            470uf 25V (3 each) P12388-ND Panasonic EEU-FM1E47 @ $.50 ea *
            2200uf 10V (2 each) P12357-ND Panasonic EEU-FM1A222 @ $.76 ea
            1000uf 25V (1 each) P12379-ND Panasonic EEU-FM1E102 @ $.76 ea
            1000uf 10V (1 each) P12353-ND Panasonic EEU-FM1A102 @ $.50 ea
            1000uf 6.3V (1 each) P12340-ND Panasonic EEU-FM0J102 @ $.37 ea

            Unit quantity. There is about a 25% discount for quan. 10


            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


              #7
              Re: HP L1740 Lcd inverter/power board

              Your first cap choice, the 470@50, is 13x25mm where the original is a 10x9mm. Can you go 25mm high?

              I asked back in the beginning how high can you go...?

              Toast
              veritas odium parit

              Comment


                #8
                Re: HP L1740 Lcd inverter/power board

                Originally posted by Toasty
                Your first cap choice, the 470@50, is 13x25mm where the original is a 10x9mm. Can you go 25mm high?

                I asked back in the beginning how high can you go...?

                Toast
                Note his 4:14 post. The original is 470 @ 25.

                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


                  #9
                  Re: HP L1740 Lcd inverter/power board

                  READ his FIRST post.

                  THEN go here:
                  http://www.mouser.com/ProductDetail/...vOCbYUtA%3d%3d

                  "Dimensions: 13 mm Dia. x 25 mm L"

                  I WAS working on this when you posted. AGE before BEAUTY....

                  veritas odium parit

                  Comment


                    #10
                    Re: HP L1740 Lcd inverter/power board

                    Ok on the panasonic caps, but one question? Can I install caps that approximately double the voltage???? I have seen several lcd repairs on youtube and read about other repairs, that the replacement caps are double the voltage than the original caps.

                    Comment


                      #11
                      Re: HP L1740 Lcd inverter/power board

                      The caps don't set or change the voltage, the circuit does.
                      The voltage marked on a cap is the caps limit.

                      If you have a piece of wire that's rated for [limited to] 250v can you safely use it on 120v?
                      - Same idea.
                      .
                      Mann-Made Global Warming.
                      - We should be more concerned about the Intellectual Climate.

                      -
                      Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

                      - Dr Seuss
                      -
                      You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                      -

                      Comment


                        #12
                        Re: HP L1740 Lcd inverter/power board

                        Originally posted by George Ortiz
                        Ok on the panasonic caps, but one question? Can I install caps that approximately double the voltage???? I have seen several lcd repairs on youtube and read about other repairs, that the replacement caps are double the voltage than the original caps.
                        You can, but I don't recommend it. Using higher voltage caps makes it more difficult to find replacements that will fit in the available space. Also, your higher voltage (and higher cost) cap will gradually reform itself to the lower voltage.

                        The original caps did not fail because the voltage was too high, they failed because the ESR (equivalent series resistance) rose as the cap aged. Eventually the capacitor overheated and popped it's top from the power it was dissipating. Panasonic FM series and similar low ESR caps from other reputable manufacturers have a much longer life expectancy.

                        PlainBill
                        Last edited by PlainBill; 10-29-2009, 12:11 PM.
                        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


                          #13
                          Re: HP L1740 Lcd inverter/power board

                          I agree.

                          There is nothing -wrong- with using a higher volts caps, it's just that it makes things harder [fitting and on your wallet] and there aren't any benefits due to the higher voltage rating.

                          If you run a 50v cap in a 16v circuit the chemistry going on inside the cap changes the thickness of the oxide layer on the aluminum to be consistent with 16v.
                          [This is called reforming, as in reforming the oxide layer.]
                          That thickness is the primary characteristic the voltage rating is based on. When it adjusts to a thickness for 16v you no longer have a 50v cap, you have a 16v cap. If you then put the reformed to 16v cap into a 50v circuit the thinner oxide layer will allow excessive currents and overheat the cap most likely to the point of it failing quickly.

                          When you see an over rated cap [higher voltage than needed] the usual reason they did that is that higher voltage caps tend to be bigger [physically] and physically bigger caps [of some given grade] have lower ESR.
                          - They didn't go up in volts for the volts, they went up for the bigger can size.
                          It's the el'cheapo way to get better ESR.
                          The two ways usually used to get better ESR:
                          - Use a physically bigger cap. [The el'cheapo way]
                          - Use a better grade of cap.

                          You are much better off using a better grade than you are going to a higher voltage.
                          For screens Panasonic FM is an excellent choice.
                          In fact [for screens] Panasonic FC or Nichicon PW are better grades than what was originally in there maybe 80-90% of the time.
                          But if you can't find the specs for the old caps to be sure FC or PW are good enough replacements then defaulting up to Panasonic FM or better is the way to go.
                          Oddly, Panasonic FM is often less expensive than FC or PW.

                          .
                          Mann-Made Global Warming.
                          - We should be more concerned about the Intellectual Climate.

                          -
                          Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

                          - Dr Seuss
                          -
                          You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                          -

                          Comment


                            #14
                            Re: HP L1740 Lcd inverter/power board

                            thanks everybody for you input and help. I am going to order from digikey
                            enough capacitors to repair all four monitors and then have enough in hand to repair another two if they (most likely will) fail. Thanks again for your help!!!!!!!

                            Comment


                              #15
                              Re: HP L1740 Lcd inverter/power board

                              All,
                              Finally was able to get a picture of one of the inverter/power supplies.
                              George
                              Attached Files

                              Comment


                                #16
                                Re: HP L1740 Lcd inverter/power board

                                Originally posted by George Ortiz
                                All,
                                Finally was able to get a picture of one of the inverter/power supplies.
                                George
                                Just a suggestion
                                It seems that you may have a problems on the back of this board judging by those burn marks, (hope I am wrong)
                                Post a picture of the back of this board (without flash please if possible)
                                BTW Your board is a Philipps I believe and dmbj is a Benq, this monitor must use both boards
                                Bob

                                Comment


                                  #17
                                  Re: HP L1740 Lcd inverter/power board

                                  Bobdee,
                                  would you happen to have any techincal information on this Philips inverter/power supply board or where I could get it. Real hard to find.
                                  Thanks,
                                  George

                                  Comment


                                    #18
                                    Re: HP L1740 Lcd inverter/power board

                                    Originally posted by George Ortiz
                                    Bobdee,
                                    would you happen to have any techincal information on this Philips inverter/power supply board or where I could get it. Real hard to find.
                                    Thanks,
                                    George
                                    Afraid not, sorry this board is new to me
                                    Suggested a picture of back of board because it sounds like faulty inverter or CCFLs, and the dark heat area is probably the mosfets the members helping you will need to see the other side

                                    Comment


                                      #19
                                      Re: HP L1740 Lcd inverter/power board

                                      Originally posted by Bobdee
                                      Afraid not, sorry this board is new to me
                                      Suggested a picture of back of board because it sounds like faulty inverter or CCFLs, and the dark heat area is probably the mosfets the members helping you will need to see the other side
                                      Right, the discoloration is extreme, but could be nothing more than the result of running for an extended time with failing caps. Unless the traces have actually lifted from the substrate it is possible to replace any shorted transistors.

                                      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


                                        #20
                                        Re: HP L1740 Lcd inverter/power board

                                        PlainBill,
                                        I checked on the other board that I have at home. This is my prototype repair board.
                                        It has the same discoloration as the board I have here at work (the one photograhed here). There is another board with the same burn marks. All have blown caps.
                                        Looks like running for extended time with failing caps. There are no circuit board tracks lifted on the other side of the boards.
                                        Last edited by George Ortiz; 11-04-2009, 10:12 AM.

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