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Sharp LC-60SQ15U TV DPS-167CP - No power

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    Sharp LC-60SQ15U TV DPS-167CP - No power

    Hi everyone!

    This Sharp LC-60SQ15U TV was hit by a near lightning strike. The Delta DPS-167CP power supply has no power output at all, thus no power to the screen, no LEDs, etc. My first order of business is to try to figure out why it doesn't have any 5V constant output.

    The fuse at F7001 is fine. The large rectifier at BD7001 has 160.3VDC measured on the far leads. All the capacitors look visually OK and test OK with an in circuit ESR tester. A quick check of the resistors doesn't show any that are open circuit, but I haven't checked their exact measurements yet. I'm working on tracing where the 5V constant comes from, but thought I'd start a post to see if anyone has experience with this power supply. Any common faults or places to start looking/testing?

    Many thanks, in advance.

    I've attached a couple images of the power supply. Also, ShopJimmy has some good photos: http://www.shopjimmy.com/sharp-runtk...-led-board.htm
    Attached Files

    #2
    Re: Sharp LC-60SQ15U TV DPS-167CP - No power

    Check fusible resistor R7900 (2.2 Ohms) to see if it is open.
    IC7903 is the STBY SMPS IC which drives the power transformer T7901, D7950 is the rectifier diode on the Cold side.
    You should run the power supply board by itself to see if you do have STBY Voltage or not.
    Last edited by budm; 08-02-2016, 01:02 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


      #3
      Re: Sharp LC-60SQ15U TV DPS-167CP - No power

      Originally posted by budm View Post
      Check fusible resistor R7900 (2.2 Ohms) to see if it is open.
      Thanks for the quick reply! R7900 is measuring 2.4 Ohms.

      Comment


        #4
        Re: Sharp LC-60SQ15U TV DPS-167CP - No power

        Try running the power uspply board by itself without other board connected in case the main board has shorted circuit and loaded down the STBY power supply.
        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


          #5
          Re: Sharp LC-60SQ15U TV DPS-167CP - No power

          So right now you are not getting DCV on any pins of the PD connector, verify?
          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


            #6
            Re: Sharp LC-60SQ15U TV DPS-167CP - No power

            Originally posted by budm View Post
            So right now you are not getting DCV on any pins of the PD connector, verify?
            Correct, no DCV on any any output pin. Sorry, I should have mentioned that I tested with the other boards disconnected last night. Just tested again to be certain. No output whatsoever even without load on the power supply.

            Comment


              #7
              Re: Sharp LC-60SQ15U TV DPS-167CP - No power

              Need to get the P/N of IC7903 so you can check and see if it has VCC to run the IC or not.
              You still need to check D7950 tof ind out if it is shorted or not.
              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


                #8
                Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                IC7903 looks to be an A6069H. I found this data sheet: https://cdn.badcaps-static.com/pdfs/...fdd208375d.pdf

                It's getting 161V between pins 8 and 3. I'm only measuring .031V between pins 5 and 3.

                D7950 is testing strangely. Forward voltage drop is .315V, but when I test the reverse voltage, it hunts around in between -1.5V and -1.9V before it finally settles on 0. [Edit - tested OK once removed from the circuit]

                I'm pretty sure D7904 is shorted with .012V drop in both directions. [Edit - tested OK once removed from the circuit]
                Attached Files
                Last edited by egoh; 08-02-2016, 03:24 PM. Reason: Tested some more...

                Comment


                  #9
                  Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                  OK, after looking at the board traces, the D7904 (it is the rectifier diode that convert AC from the AUX winding of the STBY transformer to provide the running VCC Voltage one the IC is in running mode) should lift up one leg off the board and test it again, if it is not tested bad then more likely the IC VCC pin 5 is shorted out or the filter cap C7906, or Zener D7910 is shorted (You can lift one leg off the board to see if the shorts will go away).
                  The SMPS IC is STR-A6000 series.
                  Attached Files
                  Last edited by budm; 08-02-2016, 02:42 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


                    #10
                    Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                    Removed and tested D7904 and D7950. They tested fine once removed from the circuit. I think I'm leaning towards the IC being shorted. I'll have to save the C7906 and D7910 test for tomorrow. I have my 4 year old watching, but his patience is about up. Thanks so much for your help! It looks like I'll have to get an order together soon.

                    Comment


                      #11
                      Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                      Originally posted by budm View Post
                      OK, after looking at the board traces, the D7904 (it is the rectifier diode that convert AC from the AUX winding of the STBY transformer to provide the running VCC Voltage one the IC is in running mode) should lift up one leg off the board and test it again, if it is not tested bad then more likely the IC VCC pin 5 is shorted out or the filter cap C7906, or Zener D7910 is shorted (You can lift one leg off the board to see if the shorts will go away).
                      The SMPS IC is STR-A6000 series.
                      Any idea what the specs are on C7906 (no markings) and D7910 (has a 202 on it)? I get a little nervous working with SMD stuff and not having a backup. Remember the good old days when everything had a schematic?

                      Comment


                        #12
                        Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                        Do not worry about the value of the cap or the diode yet, need to find out why you are getting bad reading on D7904 first, so do what I suggest first.
                        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


                          #13
                          Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                          Will do, got delayed fixing my wife's car, but I'll post back soon. Thanks again for all the help!

                          Comment


                            #14
                            Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                            Hi egoh,
                            I have the exact same board with the exact same symptoms (160 VDC at BD7001 output and no voltage at any PD connector pin). Did you ever figure it out?

                            Comment


                              #15
                              Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                              Have you done above tests suggested by budm?
                              I assume no responsibility for any stupid suggestions I might post.

                              Comment


                                #16
                                Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                                Yes, and I did find R7900 open. I'm a little confused by its color code. It is Red-Red-Gold-Gold-Silver. If I ignore the silver band, it matches the above post from budm as a 2.2 ohm 5%. Any idea what the last silver band would be? For a standard 5 band, the 3rd can't be gold.
                                Thanks.

                                Comment


                                  #17
                                  Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                                  You will need to look for shorts before replacing resistor. May have a bad IC7903 or diode
                                  I assume no responsibility for any stupid suggestions I might post.

                                  Comment


                                    #18
                                    Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                                    Originally posted by Hcarter View Post
                                    Hi egoh,
                                    I have the exact same board with the exact same symptoms (160 VDC at BD7001 output and no voltage at any PD connector pin). Did you ever figure it out?
                                    Sorry, I got busy with car and house repairs. I ended up replacing the board and haven't circled back to diagnose the original failed board.

                                    Comment


                                      #19
                                      Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                                      Update: I figured the shorted diode was the culprit so after replacing blown R7900 and shorted D7950, I powered up the board and R7900 immediately blew, but D7950 was still good. I then replaced IC7903 and R7900 and the board powered up normally! The TV works perfectly!

                                      Thank you everyone for all the help!

                                      Comment


                                        #20
                                        Re: Sharp LC-60SQ15U TV DPS-167CP - No power

                                        Originally posted by Hcarter View Post
                                        Update: I figured the shorted diode was the culprit so after replacing blown R7900 and shorted D7950, I powered up the board and R7900 immediately blew, but D7950 was still good. I then replaced IC7903 and R7900 and the board powered up normally! The TV works perfectly!

                                        Thank you everyone for all the help!
                                        What was the specs on the D7950 diode? Mine blew and the text on it is unreadable.

                                        Comment

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