Hanns-g HG281DJ stuck on self test after changing caps

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  • waigy
    Senior Member
    • Nov 2009
    • 93
    • UK

    #1

    Hanns-g HG281DJ stuck on self test after changing caps

    I had similar problems to user "usbdevice" in the hanns g mega thread here :
    https://www.badcaps.net/forum/showth...=11329&page=18

    It was taking longer and longer for the monitor to warm up (only up to about 5 or 10 minutes), but once it was warmed up it would work perfect all day.
    I could trick it into warming up quicker by pressing ctrl/alt/del and keeping the windows task manager window open.

    So I was taking a gamble when I decided to take it apart.
    I tried changing C80 and C83 as advised by a few people, I found a few 100u 16V caps in a sound blaster live.
    I know they are not great caps, but I thought I would try them first to see what happened.

    Since then all I get is the screen changing from one solid colour to another eg. red 2 seconds, blue 2 seconds.
    But I found out by accident that the monitor does the same thing if both C80 and C83 are not fitted.
    So I reckon I'm not managing to solder the caps in properly.
    I've tried lots of times now putting different caps in (I have 4 from the sound blaster) and the originals.

    I can usually fix anything, though I'm not a trained electrician.
    I was going to buy one of the repair kits, but I reckon it would be too big a job for me with my equipment.
    Does any one sell complete boards with decent caps or would any of the badcap members consider the repair if I posted the board?
  • selldoor
    Slow Learner
    • Dec 2010
    • 7870

    #2
    Re: Hanns-g HG281DJ stuck on self test after changing caps

    Are you trying it with a known source (working pc not in standby) Some monitors
    default to the self test when they cant find a source - check cable from pc.
    Please update your profile with country and mains voltage
    Please upload pictures using attachment function when ask for help on the repair
    http://www.badcaps.net/forum/showthread.php?t=39740

    Comment

    • waigy
      Senior Member
      • Nov 2009
      • 93
      • UK

      #3
      Re: Hanns-g HG281DJ stuck on self test after changing caps

      Yes the source is fine.
      I have another monitor plugged in, when I switch on the hanns-g my other monitor switches off.
      Normally if there was a graphics source problem the sreen would display "signal out of range" or similar.
      I can't get any text on screen including the hanns-g on screen menus.

      Comment

      • selldoor
        Slow Learner
        • Dec 2010
        • 7870

        #4
        Re: Hanns-g HG281DJ stuck on self test after changing caps

        What does it do when connected as sole monitor using the cable connected to the other monitor. Do you have a multimeter.
        Please upload pictures using attachment function when ask for help on the repair
        http://www.badcaps.net/forum/showthread.php?t=39740

        Comment

        • waigy
          Senior Member
          • Nov 2009
          • 93
          • UK

          #5
          Re: Hanns-g HG281DJ stuck on self test after changing caps

          It does the same when it's the main monitor.
          I have a multimeter, but I would prefer to look for a replacement board rather than making this into a marathon research and repair session.
          I know the repair kit would fix it, but just changing those two caps was tricky enough.

          Comment

          • selldoor
            Slow Learner
            • Dec 2010
            • 7870

            #6
            Re: Hanns-g HG281DJ stuck on self test after changing caps

            ok I have just skimmed parts of the big thread and if your ps board has the original caps, most of them will probably need replacing.
            Only thoughts on a replacement board would be that if it has not had the caps replaced they may well need replacing soon. Also the problem could be with the ps board or the logic board or both. If you cant get boards post pictures as in post3 of that big thread and do the checks as listed by retiredcaps.
            Please upload pictures using attachment function when ask for help on the repair
            http://www.badcaps.net/forum/showthread.php?t=39740

            Comment

            • waigy
              Senior Member
              • Nov 2009
              • 93
              • UK

              #7
              Re: Hanns-g HG281DJ stuck on self test after changing caps

              Replacement main boards seem to be impossible to find for these.
              I've spent ages searching and only found suppliers in the USA who are out of stock.

              Anybody fancy a wee winter project replacing the usual suspect caps on my main board with decent caps?

              Comment

              • waigy
                Senior Member
                • Nov 2009
                • 93
                • UK

                #8
                Re: Hanns-g HG281DJ stuck on self test after changing caps

                I hope I'm not breaking the forum rules by asking another member to repair this for me.
                Can some one let me know if I am.

                I'm just going round in circles taking out the caps removing the solder and resoldering them, but I don't have the best of equipment and I've already lifted one trace a bit so I'm not going to do any more on it myself.

                Out of all the times I've resoldered the caps I reckon I must have got a good connection at some point, so I reckon the problem could be something else now.
                Last edited by waigy; 11-01-2012, 09:57 PM.

                Comment

                • selldoor
                  Slow Learner
                  • Dec 2010
                  • 7870

                  #9
                  Re: Hanns-g HG281DJ stuck on self test after changing caps

                  You could try posting decent pictures to see if we can see anything wrong.
                  The caps from the SB may not be good - what make /series - for a power supply they need to be good quality low esr.
                  We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

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

                  Examples of what is needed
                  https://www.badcaps.net/forum/attach...1&d=1290283049

                  https://www.badcaps.net/forum/attach...7&d=1280167246
                  Please upload pictures using attachment function when ask for help on the repair
                  http://www.badcaps.net/forum/showthread.php?t=39740

                  Comment

                  • waigy
                    Senior Member
                    • Nov 2009
                    • 93
                    • UK

                    #10
                    Re: Hanns-g HG281DJ stuck on self test after changing caps

                    Hi selldoor

                    Thanks for answering again, it seems that I am going to have to try and repair this as it has been impossible to find parts online and by contacting hanns-g direct.
                    There are a few sites in USA selling the main board for 22 dollars which would be great but they are all out of stock.
                    I've contacted them all to ask if they are getting it back in stock.

                    So far I have only tried to change 2 caps but I haven't had any success doing that as I only have a soldering iron (no solder sucker etc.).
                    I have lifted one of the traces slightly so the thought of changing lots of caps is making me think I will just ruin the board.

                    The soundblaster caps have this on them :
                    wincap r85sm(m) -40 to 85 degrees c 100u 16v

                    I will take photos very soon and upload them.

                    Comment

                    • waigy
                      Senior Member
                      • Nov 2009
                      • 93
                      • UK

                      #11
                      Re: Hanns-g HG281DJ stuck on self test after changing caps

                      Here are the pics, I should be able to get them slightly sharper when the sun comes up tomorrow.
                      Attached Files
                      Last edited by waigy; 11-03-2012, 03:23 PM.

                      Comment

                      • waigy
                        Senior Member
                        • Nov 2009
                        • 93
                        • UK

                        #12
                        Re: Hanns-g HG281DJ stuck on self test after changing caps

                        Measurements taken when switched on and hdmi connected to pc with the monitor doing the self test thing.

                        The huge capacitor on the power board.
                        400v

                        CN7 starting with the black wire :
                        2.73v
                        -.002
                        4.95v
                        4.95v
                        -.002
                        12.17

                        CN5
                        brown 4.91v
                        black 4.91v

                        CN4 and 3
                        Red wire first
                        4.74v
                        -.002
                        -.002
                        0.6v
                        0.99v
                        1v
                        1.64v
                        0.94v
                        0.6v
                        0.96v
                        0.96v
                        1.66v
                        0.97v

                        C80 and c83 with original caps soldered back in
                        measured with multimeter black cable on earth

                        c80 3.17v
                        c83 1.59v

                        All of the caps on both boards look fine and no fluctuating measuments.

                        Comment

                        • waigy
                          Senior Member
                          • Nov 2009
                          • 93
                          • UK

                          #13
                          Re: Hanns-g HG281DJ stuck on self test after changing caps

                          Other symtoms.
                          When I plug my video camera into the hdmi port, I get the same results as connecting the pc.
                          The monitor power light changes from amber to blue, but it only ever shows the self test thing eg. solid colours for 2 seconds each.
                          It will stay like that for ages, I thought maybe leaving it on like that for a long time might change things once it was proeprly warmed up, but no.

                          The solid colours look perfect with no bad pixels or off colour patches, it just isn't showing any input eg. text, images or on screen menus.
                          Last edited by waigy; 11-03-2012, 09:03 PM.

                          Comment

                          • waigy
                            Senior Member
                            • Nov 2009
                            • 93
                            • UK

                            #14
                            Re: Hanns-g HG281DJ stuck on self test after changing caps

                            Can anyone see any problems with the voltage readings and images I have posted?

                            I'm going to buy a solder sucker or braid and attempt to change all 20 caps on the main board, though I'm not too confident about it.

                            Comment

                            • selldoor
                              Slow Learner
                              • Dec 2010
                              • 7870

                              #15
                              Re: Hanns-g HG281DJ stuck on self test after changing caps

                              Ok - Have you tried connecting it via the vga socket?

                              On the Main board I would replace the original 2 caps and
                              close by them there look what appear to be 2 voltage regulators U7 and U8. One looks like it may be 1.8 v and the other 3.3v but cant be sure.
                              Look at this guide:
                              https://www.badcaps.net/forum/showthread.php?p=261329
                              and test the regulators.
                              Looking at the list of voltages it is hard to tell though
                              I would guess the 400v is ok with PFC the 12 volt looks ok
                              but all the low valtages are on the low side 5v 3.3v and 1.8v are common. If the 3.3and 1.8 are derived from the 5v then it follows if that is low they all will be. After reading retiredcaps guide see if you can find any other regulators ( one for the 5v ) and test them. If it outputting less than 5v it may not be faulty - it could be an adjacent capacitor pulling it down.
                              Use a 40watt iron if you have it and use solder with lead
                              in it - the unleaded is sometimes difficult. You will also need some flux even If you are using solder with flux in, it sometimes dries out.
                              Please upload pictures using attachment function when ask for help on the repair
                              http://www.badcaps.net/forum/showthread.php?t=39740

                              Comment

                              • waigy
                                Senior Member
                                • Nov 2009
                                • 93
                                • UK

                                #16
                                Re: Hanns-g HG281DJ stuck on self test after changing caps

                                Hi selldoor thanks again

                                I have tried the vga socket, it gets the same results.
                                I will order the caps/solder braid later today so I will have a few days wait where I can do more testing/measuring etc.
                                Even if the caps are not the fault I'm assuming that it's still a good idea to have them all replaced with high quality caps?
                                Last edited by waigy; 11-05-2012, 07:40 PM.

                                Comment

                                • waigy
                                  Senior Member
                                  • Nov 2009
                                  • 93
                                  • UK

                                  #17
                                  Re: Hanns-g HG281DJ stuck on self test after changing caps

                                  Here is my caps shopping list (main board only)

                                  12 of 10uf 25v 4x7mm 105c
                                  5 of 100uf 16v 5x11 105c
                                  3 of 470uf 16v 8x11.5 105c

                                  When I search for these on the Farnell site I get up to 10 to choose from.
                                  Can somebody recommend the best ones to go for out of the 3 caps?

                                  470uf

                                  100uf

                                  10uf

                                  Also, do you think their cheapest desoldering gun would do the trick?
                                  I don't intend trying to impress the ladies with my desoldering gun so the size/quality isn't important to me (I'm also skint).

                                  Recommended braid?
                                  I only intend buying what I might need for this job only.
                                  Last edited by waigy; 11-05-2012, 10:16 PM.

                                  Comment

                                  • waigy
                                    Senior Member
                                    • Nov 2009
                                    • 93
                                    • UK

                                    #18
                                    Re: Hanns-g HG281DJ stuck on self test after changing caps

                                    I just got a good close up pic (the second one) of the area that I have attacked.
                                    The U7 voltage regulator solder is brown and crusty looking, it was like that before I touched the board (honest guv, I have a pic to prove it).
                                    I later got some solder on the rear side of U7 which I had to heat to remove, so I could well have fried it.

                                    Here are the measurements from left to right as you look at the images.
                                    Taken with the monitor on standby (orange led).

                                    U8
                                    0.01 - 0.08
                                    0.01 - 0.08
                                    3.25 - 3.30

                                    U7
                                    0.01 - 0.06
                                    3.26 - 3.31
                                    4.86 - 5.06

                                    I couldn't find these regulators in the data sheet search, so I can't check if the measurements are ok.
                                    Attached Files
                                    Last edited by waigy; 11-06-2012, 04:56 AM.

                                    Comment

                                    • budm
                                      Badcaps Legend
                                      • Feb 2010
                                      • 40746
                                      • USA

                                      #19
                                      Re: Hanns-g HG281DJ stuck on self test after changing caps

                                      U8 ia a 1.8V (You can see the V18S printed next to it) fixed 1117 series LDO regulator, it is bad!
                                      U7 is 3.3V (You can see the V33S printed next to it) fixed regulator. It is OK.


                                      1117 series LDO SOT-223 case style from DIGIKEY:

                                      Adjustable:
                                      http://www.digikey.com/product-detai...SCT-ND/1967218

                                      1.5V fixed:
                                      http://www.digikey.com/product-detai...SCT-ND/2121241


                                      1.8V fixed:
                                      http://www.digikey.com/product-detai...SCT-ND/1967216


                                      2.5V fixed:
                                      http://www.digikey.com/product-detai...SCT-ND/2121243


                                      3.3V fixed:
                                      http://www.digikey.com/product-detai...OSCT-ND/660708

                                      This is the way to figure out if the adjustable regulator is good or not:
                                      Notes: we are looking at the regulator with the Big tab up (the big tab is tied internally to the center pin).
                                      Adjustable regulator will have two resistors attached to it, one resistor (Rfb) is between pin1 and pin2, another resistor (Rg) is between pin1 and ground. Pin3 is an input pin.
                                      The voltage between the Adjust pin (left pin) and the center pin (Pin2, output) will always be 1.25V +/- 2% (this is the precision voltage reference), if it is not, it is bad.
                                      To figure out what the output voltage should be: measure the voltage between pin 1 and ground and add 1.25V to that number, that is the output voltage on pin 2 but you have to make sure you do have 1.25 between pin 1 and 2 as noted above
                                      Last edited by budm; 11-06-2012, 10:54 AM.
                                      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

                                      • selldoor
                                        Slow Learner
                                        • Dec 2010
                                        • 7870

                                        #20
                                        Re: Hanns-g HG281DJ stuck on self test after changing caps

                                        Hi Budm - completely missed the board descriptions whilst trying to read the
                                        writing on the components-
                                        The links you posted are not working?

                                        Edit - They are now.



                                        @Waigy - I have some 1.8 vrs - if you have difficulty finding them pm me.
                                        Last edited by selldoor; 11-06-2012, 10:59 AM. Reason: links updated
                                        Please upload pictures using attachment function when ask for help on the repair
                                        http://www.badcaps.net/forum/showthread.php?t=39740

                                        Comment

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