HP L1702 goes on and off

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • dvorav
    Member
    • Oct 2008
    • 43

    #21
    Re: HP L1702 goes on and off

    Yes, the monitor all goes off. And it couldn't be turned on for a while (unless you unplug it and pug it in again with some delay). Seems strange.
    And also that buzzing noise, can't determine right direction, but it seem it is going from PSU board (maybe even from the small green board on it).
    Any clues?

    Comment

    • Qwertyco
      Member
      • Apr 2009
      • 18

      #22
      Re: HP L1702 goes on and off

      I have a 2005 L1702 with the same problems, but it seems to have a different inverter board to all your photo's.
      It was flickering on for a few seconds, then losing the backlight.
      Green light is on, and the image can be seen shining a bright light on the screen.
      I changed all 13 caps, and now I don't even get the initial flickering!
      Image is still visable, so just no backlights at all now.

      What do I do next?
      "Life is like a Dancing Monkey - Pretty amusing, until it starts to lob faeces at you"

      Comment

      • PlainBill
        Badcaps Legend
        • Feb 2009
        • 7034
        • USA

        #23
        Re: HP L1702 goes on and off

        Originally posted by Qwertyco
        I have a 2005 L1702 with the same problems, but it seems to have a different inverter board to all your photo's.
        It was flickering on for a few seconds, then losing the backlight.
        Green light is on, and the image can be seen shining a bright light on the screen.
        I changed all 13 caps, and now I don't even get the initial flickering!
        Image is still visable, so just no backlights at all now.

        What do I do next?
        Post good pictures of the power supply and inverter, both top and bottom. You will have to check the fuses.

        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

        • Qwertyco
          Member
          • Apr 2009
          • 18

          #24
          Re: HP L1702 goes on and off

          Originally posted by PlainBill
          Post good pictures of the power supply and inverter. . . . .
          PlainBill
          Thanks PlainBill,
          Can't seem to upload to the forum, so they are on photobucket,
          Here you are:
          Pic 1
          Pic 2
          Pic 3
          Pic 4
          The main fuse just below the power cable is Ok. I can't see another fuse anywhere on either board!

          Thanks,
          Mike Q
          Last edited by Qwertyco; 05-14-2009, 03:16 PM. Reason: wrong link
          "Life is like a Dancing Monkey - Pretty amusing, until it starts to lob faeces at you"

          Comment

          • Bobdee
            Badcaps Veteran
            • Jun 2008
            • 461

            #25
            Re: HP L1702 goes on and off

            Top of board to the left of 1st picture behind pair of caps, looks like 3 Amp fuse
            Those new caps on inverter look like Jamicon KT, if they are is the esr low enough for inverter???

            Comment

            • PlainBill
              Badcaps Legend
              • Feb 2009
              • 7034
              • USA

              #26
              Re: HP L1702 goes on and off

              Originally posted by Qwertyco
              Thanks PlainBill,
              Can't seem to upload to the forum, so they are on photobucket,
              Here you are:
              Pic 1
              Pic 2
              Pic 3
              Pic 4
              The main fuse just below the power cable is Ok. I can't see another fuse anywhere on either board!

              Thanks,
              Mike Q
              Oops, Bobdee caught it!! Well done.

              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

              • Qwertyco
                Member
                • Apr 2009
                • 18

                #27
                Re: HP L1702 goes on and off

                Thanks for the quick response Guys!

                I did wonder what that component was, it has a 'J801' number. (Jumper?)
                I'll check it tonight.
                If it has blown, can I replace it with another type of 'off board' fuse, as I don't know where I'd find one of those?

                The new Caps came from here:
                Caps LINK
                I'm afraid I don't know what ESR means!

                Please be aware that I'm just handy at soldering and replacing things.
                I have no electronics background, (in fact I'm an offshore piping engineer!)
                "Life is like a Dancing Monkey - Pretty amusing, until it starts to lob faeces at you"

                Comment

                • PCBONEZ
                  Grumpy Old Fart
                  • Aug 2005
                  • 10661
                  • USA

                  #28
                  Re: HP L1702 goes on and off

                  ESR = Equivalent Series Resistance.
                  Resistance is for DC.
                  The same property (resistance is not correct word for AC) in caps for AC is the sum of the effects of Xc and ESR.

                  As the AC frequency goes up, Xc goes up and ESR goes down.

                  ESR is measured [Rated] at 100 kHz where Xc is nearly zero.

                  100 kHz is close to the frequency of the noise created by the SMPS that these caps are there to filter out so ESR is what we look at to know how effective a cap will be at filtering out that noise.
                  .
                  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

                  • Bobdee
                    Badcaps Veteran
                    • Jun 2008
                    • 461

                    #29
                    Re: HP L1702 goes on and off

                    Originally posted by PCBONEZ
                    ESR = Equivalent Series Resistance.
                    Resistance is for DC.
                    The same property (resistance is not correct word for AC) in caps for AC is the sum of the effects of Xc and ESR.

                    As the AC frequency goes up, Xc goes up and ESR goes down.

                    ESR is measured [Rated] at 100 kHz where Xc is nearly zero.

                    100 kHz is close to the frequency of the noise created by the SMPS that these caps are there to filter out so ESR is what we look at to know how effective a cap will be at filtering out that noise.
                    .
                    Hello PCBONEZ
                    Can you help Me and Qwertyco out with this dilemma, I use these Jamicon TK from MAPLINS in Monitor P/SUPPLY without problems but never in the Inverter, due to reading members advice that you only use good Quality low ESR caps in Inverters, the D/Sheet for these caps is as follows



                    Can these work in the Inverter at all ???
                    If so any guesses as to how long they would last given that they are rated as Standard G/Purpose caps

                    I know a little about ESR and caps only what I have read in Forum but dont fully understand it,
                    Could this be Qwertyco problem ???
                    Would appreciate any info you can give.
                    Many Thanks
                    bob

                    Comment

                    • Bobdee
                      Badcaps Veteran
                      • Jun 2008
                      • 461

                      #30
                      Re: HP L1702 goes on and off

                      Originally posted by Qwertyco
                      Thanks for the quick response Guys!

                      I did wonder what that component was, it has a 'J801' number. (Jumper?)
                      I'll check it tonight.
                      If it has blown, can I replace it with another type of 'off board' fuse, as I don't know where I'd find one of those?

                      The new Caps came from here:
                      Caps LINK
                      I'm afraid I don't know what ESR means!

                      Please be aware that I'm just handy at soldering and replacing things.
                      I have no electronics background, (in fact I'm an offshore piping engineer!)
                      Hi Qwertyco
                      I doubt if that fuse is your probem, you say you still see image if that is so then that fuse will be ok due to it being input fuse for other board, cant see inverter fuse anywhere, was wondering if there is a fuse under that glue gunge lower down the board between those 2 caps or is it just a jumper
                      Plainbill and PCBONEZ will see you right, in the meantime check your solder joints for ring cracks with a good magnifying glass on the inverter transformers and anything on a heatsink resolder if needed
                      bob

                      Comment

                      • Qwertyco
                        Member
                        • Apr 2009
                        • 18

                        #31
                        Re: HP L1702 goes on and off

                        Thanks Bobdee,
                        I'll get my Lidl magnifying glass and Aldi soldering iron out this weekend.

                        There's nothing under any of the white globs, I removed it all after I took the photo's.

                        I seem to have made this worse by changing the caps!
                        At least I got 2 seconds of flickering image before!

                        Is it usual to have so many different boards in one model of monitor?
                        I've seen pictures of 3 different versions of the power/inverter in an HP L1702 so far!
                        "Life is like a Dancing Monkey - Pretty amusing, until it starts to lob faeces at you"

                        Comment

                        • Bobdee
                          Badcaps Veteran
                          • Jun 2008
                          • 461

                          #32
                          Re: HP L1702 goes on and off

                          Originally posted by Qwertyco
                          Thanks Bobdee,
                          I'll get my Lidl magnifying glass and Aldi soldering iron out this weekend.

                          There's nothing under any of the white globs, I removed it all after I took the photo's.

                          I seem to have made this worse by changing the caps!
                          At least I got 2 seconds of flickering image before!

                          Is it usual to have so many different boards in one model of monitor?
                          I've seen pictures of 3 different versions of the power/inverter in an HP L1702 so far!
                          Hello again
                          It may seem worse but its not realy, it is your inverter that has the problem and its never that hard to put it right, transistors, or soldering, fuses ect even CCFLs sometimes, never had a transformer die on me yet and I have a lot of repaired monitors under my belt,so they should be ok with luck.
                          But those jamicon TK caps on inverter may be your problem,I do say May (I dont know for certain myself) I am eager to find out myself on that one,have to wait for PCBONEZ to reply or another helpful member even, but PCB certainly knows his caps

                          No its not that unusual for more than one board be used in the same monitor, or for that matter you sometimes find the same boards in other monitors
                          Thats why some members put their board No in there post so as it can be crossed referenced with search box,so that if you cant find info on your particular monitor then you may find info on another monitor that uses your board by searching your board No (hope that made sense)
                          bob
                          Last edited by Bobdee; 05-15-2009, 06:04 AM.

                          Comment

                          • PCBONEZ
                            Grumpy Old Fart
                            • Aug 2005
                            • 10661
                            • USA

                            #33
                            Re: HP L1702 goes on and off

                            Originally posted by Bobdee
                            Hello PCBONEZ
                            Can you help Me and Qwertyco out with this dilemma, I use these Jamicon TK from MAPLINS in Monitor P/SUPPLY without problems but never in the Inverter, due to reading members advice that you only use good Quality low ESR caps in Inverters, the D/Sheet for these caps is as follows



                            Can these work in the Inverter at all ???
                            If so any guesses as to how long they would last given that they are rated as Standard G/Purpose caps
                            Yes the Jamicon TK are general purpose. General purpose caps often don't even have ESR shown in data tables and Jamicon TK does not show it.

                            The ~best~ thing to do is look up specs of old caps and then at least match those.
                            I say that because, where one design uses two middle grade caps, another design might use one high grade cap to do the same thing.

                            -Usually- LCD screens use caps about the grade of Panasonic FC but -occasionally- they use caps closer to Panasonic FM.
                            If you don't know what the old caps were for sure it is best to "fail up" and use something like FM or better.

                            Xc + ESR is Impedance.
                            Some data tables will say Impedance and some will say ESR.
                            The reason is at 100kHz [or occasionally 120kHz] the Xc is almost zero and so at the frequency used in the data tables ESR = Impedance almost exactly.
                            Some companies use 120kHz instead of 100kHz in their data sheets.

                            I attached tables for FC and FM.
                            Look at 1000uF 6.3v in both tables and compare.

                            ESR is given as Ohms at 100kHz and at 20°C
                            Higher Ripple is given as Milliamps at 100kHz and at 105°C
                            [ Some data sheets give ESR in Milliohms instead of Ohms. ]

                            ESR and Ripple are ratings for AC characteristics.
                            If it was DC instead then ESR would be Resistance and Ripple Current would be Amps.
                            -
                            ESR tells you how easy it is for the cap to pass Ripple.
                            [Less ESR is better]
                            The Ripple Current rating tells you how much it can pass without overheating.
                            [More Ripple Current is better.]
                            .
                            Attached Files
                            Last edited by PCBONEZ; 05-15-2009, 06:04 AM.
                            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

                            • PCBONEZ
                              Grumpy Old Fart
                              • Aug 2005
                              • 10661
                              • USA

                              #34
                              Re: HP L1702 goes on and off

                              What are the old caps?
                              I have data sheets for all sorts of hard to find caps.
                              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

                              • Qwertyco
                                Member
                                • Apr 2009
                                • 18

                                #35
                                Re: HP L1702 goes on and off

                                Big thanks for all this advice!
                                I'll check the old caps tonight, non of them showed any sign if distress, but I changed them all anyway.

                                Where can we buy small quantity good quality caps in the UK?
                                Maplins is my only source (but it's turned into a toy shop these days!)

                                . . . and for future search purposes, the inverter board is a PTB-1569 dated 10/21/'04
                                and number 6832156900-01
                                "Life is like a Dancing Monkey - Pretty amusing, until it starts to lob faeces at you"

                                Comment

                                • PCBONEZ
                                  Grumpy Old Fart
                                  • Aug 2005
                                  • 10661
                                  • USA

                                  #36
                                  Re: HP L1702 goes on and off

                                  This guide is pretty good. [Site owner is moderator here.]
                                  http://www.capacitorlab.com/where-to...tors/index.htm
                                  .
                                  Last edited by PCBONEZ; 05-15-2009, 07:04 AM.
                                  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

                                  • EGuevarae
                                    Badcaps Legend
                                    • Nov 2008
                                    • 1336
                                    • USA

                                    #37
                                    Re: HP L1702 goes on and off

                                    Originally posted by Qwertyco
                                    Is it usual to have so many different boards in one model of monitor?
                                    I've seen pictures of 3 different versions of the power/inverter in an HP L1702 so far!
                                    As usual as having one PSU/Inv board in many different LCD brands/models.
                                    There are 10 kind of people in this world: those that understand binary, and those who don't.
                                    • ASUS ROG Maximus IX Code
                                    • Intel Core i5-7600K 3.8GHz
                                    • 16gb GSKILL TridentZ RGB DDR4-3200
                                    • 1 M2 SSD + 2 WD Blue 1TB (Mirrored)
                                    • Windows 10 Pro x64
                                    • GeForce GT1050
                                      2 x Acer KA240H + 1 Vewsonic VP2130 21 (a cap replacement job )

                                    Comment

                                    • Qwertyco
                                      Member
                                      • Apr 2009
                                      • 18

                                      #38
                                      Re: HP L1702 goes on and off

                                      Typical old caps I removed are marked:

                                      CapXon
                                      470uF 35v
                                      KM 105c
                                      C514
                                      VENT
                                      "Life is like a Dancing Monkey - Pretty amusing, until it starts to lob faeces at you"

                                      Comment

                                      • severach
                                        Badcaps Legend
                                        • Aug 2007
                                        • 1055
                                        • USA

                                        #39
                                        Re: HP L1702 goes on and off

                                        ESR tables aren't necessary. Ripple current tables are sufficient.

                                        Jamicon TK are low ESR caps. They are used in SMPS power supplies by many manufacturers and are suitable for LCD SMPS where quality and long life are not an issue. I have some used Jamicon here with ESR that have similar ESR to good brands:

                                        Jamicon TK 2200uf 10v 0.02 ESR
                                        Jamicon TK 2200uf 16v 0.04 ESR
                                        Jamicon TK 1000uf 10v 0.08 ESR

                                        It would be nice to have better caps but the Jamicon probably aren't the problem.
                                        sig files are for morons

                                        Comment

                                        • Bobdee
                                          Badcaps Veteran
                                          • Jun 2008
                                          • 461

                                          #40
                                          Re: HP L1702 goes on and off

                                          Originally posted by severach
                                          ESR tables aren't necessary. Ripple current tables are sufficient.

                                          Jamicon TK are low ESR caps. They are used in SMPS power supplies by many manufacturers and are suitable for LCD SMPS where quality and long life are not an issue. I have some used Jamicon here with ESR that have similar ESR to good brands:

                                          Jamicon TK 2200uf 10v 0.02 ESR
                                          Jamicon TK 2200uf 16v 0.04 ESR
                                          Jamicon TK 1000uf 10v 0.08 ESR

                                          It would be nice to have better caps but the Jamicon probably aren't the problem.
                                          I have some new jamicons TK here that I recently purchased from maplins store
                                          they read 220uf 50v = 198uf 0.20 esr
                                          ..............100uf 50v = 90uf 0.44 esr

                                          And their 100uf 25v are a lot worse, also I find all of there caps are 10 per cent or more under capataince, I asume that he used one of these three on inverter
                                          This link of jamicon clearly show you that they are standard caps and not low impedance
                                          http://www.icd-sales.com/JamiconSeriesGuide.asp

                                          hope this may help, but I am not saying this is the problem only a possibility, I hold my hands up to not knowing
                                          bob

                                          Comment

                                          Related Topics

                                          Collapse

                                          • Chrissygizmo
                                            Can i use backlights from a diffrent model tv to work mine ?
                                            by Chrissygizmo
                                            Hi all , bit of a strange one for yous here lol , ive got a samsung ue49ru7300k , backlights need replaced , however ive got some backlights from another samsung tv , i will post photos of them .. the connectors are the same & everything so im guessing they could work...
                                            11-07-2024, 03:16 AM
                                          • dome1
                                            A1708 Weird boot behaviour
                                            by dome1
                                            Hello!

                                            This is my first post here.

                                            Recently i repaired my costumers a1708, 820-00875. Where U3200 was in short, it got replaced, device started working again without problems. Fastforward 4 months and it has problems with booting.

                                            Sometimes it shows apple logo, is stuck, then shows a crash screen
                                            Sometimes it just boots normally

                                            It wont allow me boot externaly, Tried 3 diffrent osx, Bigsur, Monterey, Ventura.

                                            From what i gather i assume bios is corrupted, but what programmer do i use? where do i begin? Any help is welcome...
                                            06-29-2023, 08:48 AM
                                          • playaskillz204
                                            Microsoft Surface Bios Administration password !
                                            by playaskillz204
                                            Hello I have a Surface 8 Pro that has a Administration lock on it and it wont allow me to reinstall the OS when i try to use usb recovery OS install it still wont install. I do happen to have a usb bios flash tool its CH341A programmer. would this be suitable for unlocking this Administration password if i backup the bios ? or do i need a diffrent programmer. im fairly new to this. is there another way to do this 😭 i can boot HirensPE usb but when i try custom windows 11 pro x64 install(Not from Ms) is blocks the Install. plz help with any info anyone can provide thank you 🙏...
                                            02-11-2025, 01:37 PM
                                          • 3aris
                                            TOSHİBA L505 V13 SHUTDOWN
                                            by 3aris
                                            TOSHİBA L505 V13 NSWAA LA-5322P
                                            İt s starting with fan windows loading or entering bios after 10-15 second fan rising after shutdown
                                            l tired 2-3 times bios dump diffrent codes
                                            1-TOSHIBA SATELLITE PRO L550 NSWAA LA 5322P REV 1.0
                                            2-SAT L505 LA-5322P
                                            01-15-2025, 09:11 AM
                                          • ebyte64
                                            Bios request for Acer P214-52-58CH
                                            by ebyte64
                                            Good day.

                                            I would like to request a bios for the following laptop?

                                            Model: Acer P214-52-58CH
                                            Model No: N19Q7
                                            S/N: NXVLHE0H11204BA27600
                                            SNID: 11201936276

                                            Symptoms: Laptop powers on but no picture on screen.

                                            I have already checked voltages and all is present. I have checked resistance on the coils to see if the chipset or cpu might be shorted. All resistances look normal. I have tried diffrent ram and I have reset the bios. I have also visually inspected the board to see if anything is burnt or if there are any traces of liquid...
                                            09-25-2024, 05:59 AM
                                          • Loading...
                                          • No more items.
                                          Working...