SFH6286 Optocoupler

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • rtstorm
    Badcaps Veteran
    • Feb 2012
    • 971
    • Croatia

    #1

    SFH6286 Optocoupler

    Hi, please help me. I need to test this optocoupler but i am not sure if it is OK or not.

    I test diode test and got readings:

    between 1 and 2 = 0
    between 2 and 1 = 0

    between 3 and 4 = 1.28V
    between 4 and 3 = 1.28V

    shoud i have reading between 3 & 4? Resistance between 3 & 4 is 25 Mohm

    here is schematic
    Attached Files
    ...the quieter you become the more you are able to hear...
  • multimeter
    Badcaps Veteran
    • Jan 2011
    • 739
    • united kingdom

    #2
    Re: SFH6286 Optocoupler

    Originally posted by rtstorm
    Hi, please help me. I need to test this optocoupler but i am not sure if it is OK or not.

    I test diode test and got readings:

    between 1 and 2 = 0
    between 2 and 1 = 0

    between 3 and 4 = 1.28V
    between 4 and 3 = 1.28V

    shoud i have reading between 3 & 4? Resistance between 3 & 4 is 25 Mohm

    here is schematic
    that opto is shot,the diode led should have reading one way and not the other

    in my exp the led blows 1st.
    fixed so far...376 lg lcd tv's,24 onn tv;s,24 panasonic lcd,16 jvc lcd,12 marshall jcm800 amps,refurb of various disco equipment lighting,old style disco decks ,and a flymo!

    ----------------------------------------------
    please let us know if everything works ok if your tv gets fixed, as it will be and aid for anyone else having the same problem and wishing to fix it.it would save people clogging up this site with topics that are duplicated,and can be found easily using the search function.,and taking up valuable space.enjoy your fixed tv!,hopefully!

    Comment

    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK

      #3
      Re: SFH6286 Optocoupler

      There are two matched LEDs in that device, in inverse parallel, so reading both ways is OK.
      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

      Comment

      • selldoor
        Slow Learner
        • Dec 2010
        • 7870

        #4
        Re: SFH6286 Optocoupler

        That was my immediate thought but when you look at the picture it has two
        diodes ? so does that cancel the test out?
        Most diagrams for Optoisolators have only one diode?

        Ha - Thanks Tom beat me to it while I tried to spell optoisolator tho I wasnt sure.

        What about part two - reading between 3 & 4 - voltage reading?
        Last edited by selldoor; 02-18-2014, 01:20 PM.
        Please upload pictures using attachment function when ask for help on the repair
        http://www.badcaps.net/forum/showthread.php?t=39740

        Comment

        • rtstorm
          Badcaps Veteran
          • Feb 2012
          • 971
          • Croatia

          #5
          Re: SFH6286 Optocoupler

          it have 2 diodes on one side (1 and 2) i have reading in both way on other side (3 and 4)
          ...the quieter you become the more you are able to hear...

          Comment

          • rtstorm
            Badcaps Veteran
            • Feb 2012
            • 971
            • Croatia

            #6
            Re: SFH6286 Optocoupler

            i think part one (1 and 2) is ok, but second is i think bad. Should i have both reading between 3 and 4?
            ...the quieter you become the more you are able to hear...

            Comment

            • selldoor
              Slow Learner
              • Dec 2010
              • 7870

              #7
              Re: SFH6286 Optocoupler

              If I remember correctly it is difficult to test that 3/4 side. Look it up on google I think you need 2 analogue voltmeters. But you can test for a voltage on the board.
              Please upload pictures using attachment function when ask for help on the repair
              http://www.badcaps.net/forum/showthread.php?t=39740

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #8
                Re: SFH6286 Optocoupler

                "3 & 4 is 25 Mohm" that is just the Emitter-Collector leakage resistance.
                "between 1 and 2 = 0
                between 2 and 1 = 0"
                Do you mean 0 on you meter in Diode mode? It should show 1.1~1.5 (per spec of the Opto) reading. Note: in diode mode testing, the meter is actually showing the Vf (forward voltage) of the device.
                You can use 3V battery with 470 Ohms resistor in series to limit the current and connect it to pin 1 and 2, polarity does not matter since this is an AC input Opto (it does not care about the polarity of the input voltage due to dual LED inside). On the output side you can set your meter to 200 Ohms or 2K or in continuity mode (this will depend on the meter spec), you should see low resistance when the battery is connected to 1 & 2 with that resistor in series.
                Last edited by budm; 02-18-2014, 03:05 PM.
                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

                • rtstorm
                  Badcaps Veteran
                  • Feb 2012
                  • 971
                  • Croatia

                  #9
                  Re: SFH6286 Optocoupler

                  Originally posted by budm
                  "3 & 4 is 25 Mohm" that is just the Emitter-Collector leakage resistance.
                  "between 1 and 2 = 0
                  between 2 and 1 = 0"
                  Do you mean 0 on you meter in Diode mode? It should show 1.5~1.8 reading. Note: in diode mode testing, the meter is actually showing the Vf (forward voltage) of the device.
                  I mean 0 like no connection, yes 0 in diode mode.
                  ...the quieter you become the more you are able to hear...

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #10
                    Re: SFH6286 Optocoupler

                    No, it should not show no connection, get 2 red LEDs and connect them back to back just as shown and test with your meter, that is about the reading it should show.


                    They are just 2 LEDs back to back inside.
                    Last edited by budm; 02-18-2014, 03:09 PM.
                    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

                    • rtstorm
                      Badcaps Veteran
                      • Feb 2012
                      • 971
                      • Croatia

                      #11
                      Re: SFH6286 Optocoupler

                      Originally posted by budm
                      "3 & 4 is 25 Mohm" that is just the Emitter-Collector leakage resistance.
                      "between 1 and 2 = 0
                      between 2 and 1 = 0"
                      Do you mean 0 on you meter in Diode mode? It should show 1.1~1.5 (per spec of the Opto) reading. Note: in diode mode testing, the meter is actually showing the Vf (forward voltage) of the device.
                      You can use 3V battery with 470 Ohms resistor in series to limit the current and connect it to pin 1 and 2, polarity does not matter since this is an AC input Opto (it does not care about the polarity of the input voltage due to dual LED inside). On the output side you can set your meter to 200 Ohms or 2K or in continuity mode (this will depend on the meter spec), you should see low resistance when the battery is connected to 1 & 2 with that resistor in series.
                      i try this, and i do not have low resistance on output. So can we confirm that this optocoupler is bad?
                      ...the quieter you become the more you are able to hear...

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #12
                        Re: SFH6286 Optocoupler

                        I think it is bad due to 0 reading on pin 1 and 2 as you reported so the Phototransistor inside does not detect anything from the LEDs.
                        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

                        Related Topics

                        Collapse

                        • khelane
                          test active pfc power with lamp test
                          by khelane
                          Hello
                          I have a big problem and that is that in some cases when repairing active pfc power supplies I cannot work with a test lamp. I can only get help with 5 volts standby and for starting and starting I have to work without a lamp and this way there is a possibility of parts exploding and other parts being added.
                          Sometimes with a multimeter test the problems can be reduced to some extent, but I had several cases that had to be tested on and online and recently two varistors exploded. They had terrible resistance because the power supplies were over 800 watts.
                          Is there a way...
                          06-03-2025, 01:00 AM
                        • chronic519
                          Mats / mods: detected and repaired GPU fault. Cant seem to test after!
                          by chronic519
                          Hello.

                          GPU came in, green lines. Spent lots of time using to get the Mats / mods drive working (found on youtube).
                          Found issue with a RAM block
                          Replaced, green lines gone.
                          Trying to test again, assuming getting the false positive. Originally had over 1K on a single bank. Now getting tosses low between banks.
                          Used a good card to test and same results low errors 32+.

                          I am just search for some form of command to do a full test on the GPU.
                          I just ran the mats command with my good GPU and passed after roughly 40 min.
                          The repaired one, ran...
                          05-20-2025, 07:56 PM
                        • tvguy12012012120
                          Zombie Samsung UN55NU6900F dead / no standby voltage - randomly came to life after hours of troubleshooting then died
                          by tvguy12012012120
                          This is my first attempt at troubleshooting a board like this, I know I could just buy a new board but I'm curious to figure out how this works. I've been testing different components in the evenings this week and I think the problem is with the IC failing to start up for some reason. When the board is plugged in there is no standby voltage.

                          Then today it randomly sprung to life like a zombie but shortly died thereafter. I have no idea why it would have done that and its the first time I've seen it running. I discharged capacitors on the board last night, then it was sitting today....
                          02-07-2025, 05:13 PM
                        • alltvrepairs
                          Lg TCon test pins for screen test
                          by alltvrepairs
                          Hi,
                          i have a 65 Panasonic TX-65HX710E using vestel 17MB170 main and Lg tcon.

                          Few drops of water fell probably near COF and have no display. Tried removing tabs but no.part of display present as if tcon fuse open. However 12v is present and tcon can be felt warm enough that supplies are present. Backlight and sound ok.

                          Anyone knows if this TCon 6870c-0805A has any special test pins for rgb test?

                          Appreciate your help....
                          06-13-2025, 06:33 AM
                        • signal.quest
                          Samsung LN40C630K1F LCD TV No Backlights and Flashlight Test Fail
                          by signal.quest
                          Hi all,

                          I have been working on a Samsung LN40C630K1F LCD TV. On power up the backlights only briefly light up when first powered on then they go out (2 seconds to black). The flashlight test also fails. The sound works fine. Please see attached pics.

                          I have researched the forums a lot. I have watched the videos of trying to locate the bad CCFL or transformer and bypassing. I can't find any evidence of a bad transformer/CCFL. I verified I get 376V from the big caps to the fuse. I have used a small/cheap oscilloscope and it looks like the MOSFETs on the inverter...
                          09-30-2024, 11:21 PM
                        • Loading...
                        • No more items.
                        Working...