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    Samsung 710N (and others ....)

    I am slowly accumulating a pile of Samsung LCD's with fairly similar main/video board problems. The latest is a 710N. Powers up with green LED, which disappears after 6 seconds. As this is driven by the micro it ?confirms micro activity. The video chip has a 12MHz crystal, and the SM shows it driving the micro oscillator. Apologies for the dodgy pic.

    There are NO reset chips. The micro outputs a reset_scaler signal to the video (scaler) chip. (The micro is an NT68F63L.)

    The VGA sync signals are fed to the micro, so it appears that it fails to detect a signal, gives up and goes into sleep mode.

    All voltages are good. No video is presented to the screen. Forcing BL_EN gives a well-lit screen. Hitting the MENU button gives a "test good" message box

    Stumped.
    Attached Files
    Friends don't let friends buy Samsung ....

    #2
    Re: Samsung 710N (and others ....)

    Originally posted by pedro
    Samsung 710N. Powers up with green LED, which disappears after 6 seconds. As this is driven by the micro it ?confirms micro activity. The video chip has a 12MHz crystal, and the SM shows it driving the micro oscillator. Apologies for the dodgy pic.

    There are NO reset chips. The micro outputs a reset_scaler signal to the video (scaler) chip. (The micro is an NT68F63L.)

    The VGA sync signals are fed to the micro, so it appears that it fails to detect a signal, gives up and goes into sleep mode.

    All voltages are good. No video is presented to the screen. Forcing BL_EN gives a well-lit screen. Hitting the MENU button gives a "test good" message box

    Stumped.
    I somehow managed to get it to reset. Now on power-up the green LED lights for about 1.5 secs then goes off. No screen/BL activity. If I then press the ON switch instead of a blank screen it shows a floating "check signal cable" box indefinitely if no video cable is connected, LED remains on.

    The instant a video cable is connected from a source (with video signal on or off) to the monitor the BL goes off, and the green power LED extinguishes about 2 secs later. Disconnecting the video cable results in the LED and the message box returning after about 2 secs.

    Googling for the NT68F63L gave a heap of hits (but no data sheet). It seems to be a problematic device, with a couple of websites suggesting connecting a 50ohm resistor between pin 5 (+5V) and pin 6 ("V33", biased internally to 3.3V) to pull V33 up to ~ 4.1V will restore functionality.
    Friends don't let friends buy Samsung ....

    Comment


      #3
      Re: Samsung 710N (and others ....)

      I assume that no-one has any suggestions - other than the dumpster - for this monitor.

      The kluge I mentioned earlier is at http://www.ehow.com/how_4758816_repa...d-monitor.html and has been repeated elsewhere for issues similar to the one I have here, but it goes against the grain to re-bias a "V33" pin from the 3.3V it currently has to a bit over 4 volts.

      Originally posted by pedro
      If I then press the ON switch instead of a blank screen it shows a floating "check signal cable" box indefinitely if no video cable is connected, LED remains on.
      Can anyone with a normally funtioning Samsung 710N confirm whether this behaviour ("check signal cable" message appears when powered up and no video signal source connected) is normal?
      Friends don't let friends buy Samsung ....

      Comment


        #4
        Re: Samsung 710N (and others ....)

        Hey people first post!

        Pedro i too have a 710N with what seems to be the same problem.

        Pressing power button without the monitor cable plugged in i get the "Check Signal Cable" dialog, when pressing the power button with the cable plugged in i get the green light for about 3 seconds and then the monitor switches off but before it switches off i can get the "test good" dialog by hitting MENU.

        Caps on the logic board were tested with a Blue ESR meter and these are the results, now they look like they all need changing to me but i'm still quite new to all this with only a few successful lytic recaps under my belt.

        C611 (100uF 16V) = .16
        C607 (100uF 16V) = 1.0
        C612 (100uF 16V) = .12
        C609 (100uF 16V) = .69
        C401 (100uF 16V) = .19
        C422 (10uF 16V) = .65

        Pedro what are yours testing?

        Comment


          #5
          Re: Samsung 710N (and others ....)

          Originally posted by jay007
          Caps on the logic board were tested with a Blue ESR meter and these are the results, now they look like they all need changing to me but i'm still quite new to all this with only a few successful lytic recaps under my belt.

          C611 (100uF 16V) = .16
          C607 (100uF 16V) = 1.0
          C612 (100uF 16V) = .12
          C609 (100uF 16V) = .69
          C401 (100uF 16V) = .19
          C422 (10uF 16V) = .65

          Pedro what are yours testing?
          Mine are .21, 1.2, .24, .70, .18, .73 in order. Clearly some effects from circuitry as they should all be the same, but mine pretty much mimic yours.

          I wouldn't get too excited about those numbers. The SMD electros - even "low ESR" types, have higher readings than typical through-hole (radial) low-ESR tpyes. For example, the Panasonic FC SMD 100/16V lists as 0.6 ohm

          http://au.farnell.com/panasonic/eeef...t=EEE-FC1C101P

          Also note that the parts list in the SM shows these as:

          C-AL, SMD. 100uF, 20%, 16V, GP, TP, 6.6*6.6*5.4mm

          which means general purpose, not low ESR, so on that basis I'm not about to replace them. I *may* tack a radial across each to improve the ESR somewhat but if I do I won't be expecting anything dramatic.
          Friends don't let friends buy Samsung ....

          Comment


            #6
            Re: Samsung 710N (and others ....)

            Originally posted by pedro View Post
            It seems to be a problematic device, with a couple of websites suggesting connecting a 50ohm resistor between pin 5 (+5V) and pin 6 ("V33", biased internally to 3.3V) to pull V33 up to ~ 4.1V will restore functionality.
            I just ran across a 710n with this issue. I have also had some very similar symptoms with Samsung 910v's...

            Just wondering if anyone has tried the fix above, or any other tips. Thanks.

            Comment


              #7
              Re: Samsung 710N (and others ....)

              I searched around on the internet and most of the posts that say the resistor helped had a different symptom. Their display had an "optimal resolution..." message when the vga cable was plugged in. Mine does as described above:
              on power-up the green LED lights for about 1.5 secs then goes off. No screen/BL activity. If I then press the ON switch instead of a blank screen it shows a floating "check signal cable" box indefinitely if no video cable is connected, LED remains on.

              The instant a video cable is connected from a source (with video signal on or off) to the monitor the BL goes off, and the green power LED extinguishes about 2 secs later. Disconnecting the video cable results in the LED and the message box returning after about 2 secs.

              Comment


                #8
                Re: Samsung 710N (and others ....)

                We have a Samsung 204b monitor at work with similar symptoms and we have yet to find a solution except that the main micro on the video board has to be bad.

                Our symptoms is simply a floating "no signal" box but the only difference is that ours does the same thing with a signal applied. SAMSUNG IS THE WORK OF THE DEVIL!!!
                The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

                Comment


                  #9
                  Re: Samsung 710N (and others ....)

                  You are wasting your time with this monitor.

                  See my thread here

                  I spent $25 with Digikey and it was a complete waste. I recapped the power board with all UCC LXZ or LXY and when I turned it on, I got the exact same thing that this individual describes:
                  When I removed the signal cable and switched 'on', now I could see the check signal cable OSD appeared at the screen.
                  The funny thing was, that the monitor _DID_ work before the recap but would cease to work after a short time.
                  "We have offered them (the Arabs) a sensible way for so many years. But no, they wanted to fight. Fine! We gave them technology, the latest, the kind even Vietnam didn't have. They had double superiority in tanks and aircraft, triple in artillery, and in air defense and anti-tank weapons they had absolute supremacy. And what? Once again they were beaten. Once again they scrammed [sic]. Once again they screamed for us to come save them. Sadat woke me up in the middle of the night twice over the phone, 'Save me!' He demanded to send Soviet troops, and immediately! No! We are not going to fight for them."

                  -Leonid Brezhnev (On the Yom Kippur War)

                  Comment


                    #10
                    Re: Samsung 710N (and others ....)

                    I just found another 710n last night...

                    The PSU is the same for this model: FSP035-2PI01

                    But the chip on the logic board is by Samsung, not the dreaded SE7889-LF. The revision is also older and the PCB revision is 1.0 instead of 1.4, year is July 2005.

                    Either Samsung tried to cut costs, or they tried to improve it.

                    So it might be worthwhile to recap it. This time I'll go for something better than the LXZ I tried last time.
                    "We have offered them (the Arabs) a sensible way for so many years. But no, they wanted to fight. Fine! We gave them technology, the latest, the kind even Vietnam didn't have. They had double superiority in tanks and aircraft, triple in artillery, and in air defense and anti-tank weapons they had absolute supremacy. And what? Once again they were beaten. Once again they scrammed [sic]. Once again they screamed for us to come save them. Sadat woke me up in the middle of the night twice over the phone, 'Save me!' He demanded to send Soviet troops, and immediately! No! We are not going to fight for them."

                    -Leonid Brezhnev (On the Yom Kippur War)

                    Comment


                      #11
                      Re: Samsung 710N (and others ....)

                      Got one of those monitors.
                      Without any cable connected, powers up and displays something in russian language which I think is "no signal detected".
                      When I connect it to a PC, black screend and power down in some seconds.
                      There are no bad caps, surprinsingly for a monitor made in 2004 with Sam Young caps. The worst one shown 0.32 ohms, while others were around 0.03 to 0.05ohms. The one with 0.32 ohms was a 330uF on the 5v rail to the logic card, exchanged with a Chemicon LXZ series. Anyway, the capacity was on accepted range.
                      Picture with logic card attached.
                      Attached Files

                      Comment


                        #12
                        Re: Samsung 710N (and others ....)

                        I to have a Samsung 710N with the same problem as Pedro. Did the 47 ohm resistor trick and it turned into the "optimal resolution" problem with an occasional turning on of the display. So I went and removed the 47 ohm resistor and accidentally bridged pins 5 & 6 with solder in doing so. So I went ahead and tried it with the pins bridged. Guess what? The monitor is up and working. It might be worth a try if you are having this problem. No guarantee this will work in all cases.
                        Original voltage at pin 6 was 3.2 volts and after the 47 ohm resistor the voltage was 4.4 volts and now it is the same as pin 5 at 5.1 volts.

                        Comment


                          #13
                          Re: Samsung 710N (and others ....)

                          i solved the broblem with a 18k resistor ant those pins . all ok thanks mates

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