Samsung SyncMaster 204b

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • whotopia
    New Member
    • Oct 2013
    • 8
    • Switzerland

    #1

    Samsung SyncMaster 204b

    I have 3 Samsung 204b monitors. 1st-dead after period of long startup times, 2nd-long time to start up, 3rd seems relatively fine.

    I bought appropriate capacitors from Digi-Key. For PSU (on 1st unit) I had to replace 3x330uf, 2x820uF & 1x47uF. Hopefully the other 3 monitors are the same as I bought them all at once.

    After replacing caps monitor #1 still doesn't work. Some debugging: 13v present to main board, C105 has around 130V on it when on (with switch). Sometimes when I turn the unit on, the blue light will be on power briefly, but typically not (still a charged cap problem)?

    Could the problem be the main board? I could test this theory by swapping main board from a working monitor. Could I harm the main board? Is it better to see if I actually fixed the power supply by swapping that into a unit where the main board is working?
    Any other test points I should check?
  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #2
    Re: Samsung SyncMaster 204b

    Any pictures of the boards? There are more than one version of this model.
    http://s807.photobucket.com/user/bud...?sort=3&page=1
    http://s807.photobucket.com/user/bud...?sort=3&page=1
    http://s807.photobucket.com/user/bud...?sort=3&page=1
    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

    • whotopia
      New Member
      • Oct 2013
      • 8
      • Switzerland

      #3
      Re: Samsung SyncMaster 204b

      Hi,
      I've attached 2 pics of the PS board and the main logic board. After a bit more debugging, still no luck. However, I did find and buy a replacement PS for only 23usd on eBay. Once it arrives that may be helpful. I still haven't disassembled my other 2 semi-working monitors because I'm using them.
      Attached Files

      Comment

      • whotopia
        New Member
        • Oct 2013
        • 8
        • Switzerland

        #4
        Re: Samsung SyncMaster 204b

        So I swapped in the new power supply, and there was NO improvement.
        Therefore the problem must be with the Logic/Driver. I ordered a new one from here:
        http://www.baoseek.com/index.php?mai...id=24434988294
        But there are plenty of other source online for purchase.

        I'd still like to get this logic board working. Can anyone suggest e.g. the top 5 things that may be broken?

        Thanks!

        Comment

        • barthez
          New Member
          • Dec 2013
          • 5
          • Germany

          #5
          Re: Samsung SyncMaster 204b

          Apparently I'm stuck with the same problem as whotopia. I've got two 204B monitors. The first (A) failed years ago, but is working fine since replacement of the caps. Now the second (B) showed the known symptoms. I replaced the caps but the monitor won't power up.

          By exchanging power boards and logic boards between the two monitors, I've confirmed both power boards to work fine, but the logic board from B causes the following behaviour: When the mains switch is turned on, the power button LED on the front panel lights up once. Same behaviour with all other parts exchanged (power board, LCD panel, control panel).

          I'm more a software guy, so I'm at a loss as to what I should test next. Any hints will be much appreciated!

          The logic board:
          http://s1.directupload.net/file/d/3463/4tcuqrvn_jpg.htm

          Comment

          • Davi.p
            Badcaps Legend
            • Sep 2009
            • 4265
            • Italy - Milan

            #6
            Re: Samsung SyncMaster 204b

            Barthez as from the picture test the voltage on the electrolytic more to the left and the big pin on the 3 legs chip "1084-33"..

            Comment

            • barthez
              New Member
              • Dec 2013
              • 5
              • Germany

              #7
              Re: Samsung SyncMaster 204b

              Davi.p, thanks for your reply! I've measured as per your post and a few other points: http://s1.directupload.net/file/d/3464/pcgvs586_jpg.htm

              Comment

              • selldoor
                Slow Learner
                • Dec 2010
                • 7870

                #8
                Re: Samsung SyncMaster 204b

                those vrs look ok
                It is useful for future help seekers if you upload the pictures to badcaps


                Failure of these boards is common and difficult to pinpoint.
                could be the genesis chip or any of the dozen small switching transistors.

                How many of us switch everything off before plugging stuff in??
                Attached Files
                Last edited by selldoor; 12-07-2013, 06:10 AM.
                Please upload pictures using attachment function when ask for help on the repair
                http://www.badcaps.net/forum/showthread.php?t=39740

                Comment

                • Davi.p
                  Badcaps Legend
                  • Sep 2009
                  • 4265
                  • Italy - Milan

                  #9
                  Re: Samsung SyncMaster 204b

                  The readings seems to be ok.. unfortunately ..
                  i only have a doubt on that cap marked with a 0,17v reading,
                  Barthez do you confirm the same as whotopia, therefore the mon. came dead gradually?
                  there's no much logic but can you test without power the transistor Q301 near the previous cap? After that try to put power and measure voltage on Q301 leg's down right, if is not it it's the down left, you must read i think 5v, i think it's a P mosfet.

                  Comment

                  • barthez
                    New Member
                    • Dec 2013
                    • 5
                    • Germany

                    #10
                    Re: Samsung SyncMaster 204b

                    selldoo, Davi.p, thanks! The monitor died a slow, flickering death. Since I knew the problem from its sibling, I wasn't too worried. Maybe I killed an IC with a static discharge while removing the power board?

                    The code on the transistor looks like "TR7 N". I found a datasheet for TR7, which seems to be matching what you wrote, Davi.p:

                    With the red probe on the top pin (drain?), I get 6,2 kΩ to bottom right (source?) and 51.6 kΩ to bottom left (gate?). With the black probe on the top pin, I get 17 kΩ to bottom right and 115 kΩ to bottom left. Powered on, I get 5 V on bottom right, 4.54 V on bottom left, and top 0.17 V.

                    Comment

                    • Davi.p
                      Badcaps Legend
                      • Sep 2009
                      • 4265
                      • Italy - Milan

                      #11
                      Re: Samsung SyncMaster 204b

                      Originally posted by barthez
                      Maybe I killed an IC with a static discharge while removing the power board?
                      in don't know but i think not.

                      Originally posted by barthez
                      The code on the transistor looks like "TR7 N". I found a datasheet for TR7,
                      it is that..

                      Originally posted by barthez
                      With the red probe on the top pin (drain?), I get 6,2 kΩ to bottom right (source?) and 51.6 kΩ to bottom left (gate?)...
                      i'm not confident with the ohm measurements, i use diode mode, anyway it seems that is not opened/shorted, please, tell me the panel (not monitor) model.. i would like to see if in these nowadays models there is a sort of serial comm that inform the mainb. if the panel is working..
                      i would want to say that these tests are a very little hope..
                      Last edited by Davi.p; 12-09-2013, 11:13 AM.

                      Comment

                      • barthez
                        New Member
                        • Dec 2013
                        • 5
                        • Germany

                        #12
                        Re: Samsung SyncMaster 204b

                        Originally posted by Davi.p
                        i'm not confident with the ohm measurements, i use diode mode, anyway it seems that is not opened/shorted,
                        Using diode mode, I get "1" from top to bottom left and from bottom left to bottom right – both ways. For top to bottom right I get 1890 with the black probe at the top pin and 368 the other way round.

                        Originally posted by Davi.p
                        please, tell me the panel (not monitor) model.. i would like to see if in these nowadays models there is a sort of serial comm that inform the mainb. if the panel is working..
                        i would want to say that these tests are a very little hope..
                        That would be "LTM201UX-L01", I guess. The panel is OK, as verified using the logic board from the other 204B.

                        Comment

                        • Davi.p
                          Badcaps Legend
                          • Sep 2009
                          • 4265
                          • Italy - Milan

                          #13
                          Re: Samsung SyncMaster 204b

                          there is anything like what i said about the panel, therefore i say that this path is unuseful.. sorry.. the p-mosfet switches panel on and off (for energy saving for example) but if he stay off is probably due to a malfunction of the mcu or what else, but i think not an IC becouse usually them fails in one time, the only thing remains to think to from what i've read on repairing guides is the quarz crystal oscillator.

                          Comment

                          • barthez
                            New Member
                            • Dec 2013
                            • 5
                            • Germany

                            #14
                            Re: Samsung SyncMaster 204b

                            Thanks, Davi.p! If I read correctly, you're saying the mosfet is OK? Then, why don't the 4.5 V on the gate (?) suffice to make more of the 5 V on source flow through the mosfet to drain? My apologies if my question doesn't make any sense, last time I tried to learn some electronics theory I was a good 20 years younger…

                            Later this week I'll replace my old 204Bs, then I can cross-check between the working logic board and this one.

                            Comment

                            • Davi.p
                              Badcaps Legend
                              • Sep 2009
                              • 4265
                              • Italy - Milan

                              #15
                              Re: Samsung SyncMaster 204b

                              plus.. on a Italian forum i've read about a tv equipped with a service rs232 line, it would not turn on, by connecting a pc he saw that it powered up correctly but it would not continue to boot, by sending a sequence of Esc characters it has booted and the tv became fully usable even in next times.. this is called programmed obsolescence...

                              Comment

                              • whotopia
                                New Member
                                • Oct 2013
                                • 8
                                • Switzerland

                                #16
                                Re: Samsung SyncMaster 204b

                                I now have an oscilloscope at home for another project. I'm also going to try to cross check the logic board against a working in the coming days (weeks? have a day job too )
                                The replacement board that ordered from China still hasn't arrived Hope I haven't been scammed there.

                                Comment

                                • whotopia
                                  New Member
                                  • Oct 2013
                                  • 8
                                  • Switzerland

                                  #17
                                  Re: Samsung SyncMaster 204b

                                  Probably final update on this issue.

                                  I ended up buying a replacement logic board for the monitor from DHgate. The board seemed to work fine until I connected the monitor to my hackintosh. Then, it would go black for a few seconds every few minutes. Weird.

                                  After a bit of googling around, I discovered this is a known problem with 204B and some video cards. Apparently at full resolution 1600x1200 some 204B logic boards cannot handle 60Hz input. Sure enough, I tested the monitor at other resolutions and refresh rates, and all was well. I decided I would live with this issue, though my other 2 monitors work fine at 60Hz. There is a utility out there for OS X called SwitchResX which allows fine control of the refresh rates on multi-monitor configurations. I bought this little utility, set all the monitors to refresh at 58Hz, and now all is well. I'm pleased with the results, and this will hold me until I ultimately decide to replace all 3 screens.

                                  Comment

                                  • jetadm123
                                    Badcaps Legend
                                    • Feb 2010
                                    • 2169

                                    #18
                                    Re: Samsung SyncMaster 204b

                                    Thanks for reporting back on this issue. Many people don't give feedback on whether they got their monitor working and it adds to the frustration as to whether member's suggestions are helping or not.

                                    Comment

                                    Related Topics

                                    Collapse

                                    • Asraf Atb
                                      Help Needed: Samsung UE55MU8000 Dead - Possible Main Board Issue
                                      by Asraf Atb
                                      Hi everyone,

                                      Im looking for some advice regarding my Samsung UE55MU8000 TV with main board model BN94-11606C. The TV suddenly stopped turning on and now shows no signs of life at all not even the standby light at the bottom.

                                      Initially, I suspected an issue with the PSU, so I took it to a repair center. They tested it and confirmed that the PSU works perfectly, even on other TVs. Based on that, I started investigating the main board.

                                      I disconnected the main board from the PSU, and the backlight turned on, which seems to confirm the main board is the issue....
                                      01-27-2025, 05:02 PM
                                    • Dani_2024
                                      Sceptre U550CV-UMR 4K LED, Bad Caps on Main Power Board?
                                      by Dani_2024
                                      Hi and thanks in advance for any input you might provide!
                                      I have a Sceptre U550CV-UMRD8POTV83BB 4K LED (this is a dumb tv) that I bought new in August 2021, so It's just completed 3 years.
                                      Main power board model: TP.MS3683.PC821 T-Con board: N4TP546UHDPU2L_BO

                                      Last Sunday I was watching a dvd and fell asleep for about half hour, when I awoke the tv screen was black and couldn't get the dvd menu to show, so I changed the input to antenna and had sound but no picture, turned it off. I then got online and found this great site! ....read many troubleshooting tips and this...
                                      10-28-2024, 05:06 PM
                                    • Lee M.
                                      Samsung UN75RU8000FXZA bad main board?
                                      by Lee M.
                                      When plugged in it will click and cycle the BL on and off, no pic and does not respond to remote. When I disconnect the cable from the PS board to the main board and then plug it in the BL will come on and stay on. There are only two boards in this set, the LVDS cables from the panel driver boards connect directly to the main board. Since the BL comes on and stays on I'm thinking the PS board is ok and the problem is on the main board. Should I order another main board or do I need to do more testing? thanks, Lee
                                      11-08-2023, 07:46 PM
                                    • jb_Bak
                                      Sony xbr-65x900c main board issues?
                                      by jb_Bak
                                      Hey guys great forum glad to have found it. I bought a Sony XBR 65X900C cheaply because it didn't work. No signs of life at all not even a light/led. All I hear is a brief high voltage sound when I throw the power to it.

                                      Didn't see any obvious signs of damage so right away started checking voltages. This is what I see:
                                      Power Board Connector that goes to Main board
                                      CN6401
                                      Pin 01 NC
                                      Pin 02 NC
                                      Pin 03 "BL_ON": 0V
                                      Pin 04 "N/C"
                                      Pin 05 "STBY 3.3V": 3.5V
                                      Pin 06 "GND": N/C
                                      Pin 07 "AC_OFF"...
                                      09-27-2021, 04:52 PM
                                    • JDC
                                      (SOLVED) - ONN 100012588 No Power, Then Rebooting After Main Board Change
                                      by JDC
                                      ONN 100012588
                                      Issue: No Power, Then Rebooting After Main Board Change

                                      Short answer: replace main board and power board
                                      Technical answer: replace main board and Q306 & Q307 on power board.

                                      Long answer:

                                      TV wouldn't turn on. Power switch was fine which means the main board isn't processing the power on signal. Replaced main board. TV turns on now but randomly reboots. Bad main board? EEPROM? Tried to pull main board and got a shock touching the corner of the board. That's weird. C334 (450V 10uf) capacitor is still holding a high charge....
                                      07-15-2022, 07:39 AM
                                    • Loading...
                                    • No more items.
                                    Working...