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Vizio TV E470VL SMPS Flucuation Output Voltage

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    #61
    Re: Vizio TV E470VL SMPS Flucuation Output Voltage

    I have ordered a new IC and optocoupler. I will update with results once those are installed.

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      #62
      Re: Vizio TV E470VL SMPS Flucuation Output Voltage

      I replaced the IC and optocoupler and unfortunately the fluctuating voltage is the same as before, between 9 and 10 volts at Vcc and about 2 volts at the 5 volt output

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        #63
        Re: Vizio TV E470VL SMPS Flucuation Output Voltage

        So I guess pin 4 is still 0 volts?
        Have you tried replacing C104 & C105?

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          #64
          Re: Vizio TV E470VL SMPS Flucuation Output Voltage

          Pin 4 is zero volts, C104 and 105 test ok with an ESR Meter. ZD251 is just below the voltage outputs on the bottom of the board. Measuring one way is .731 the other 1.671 is that a normal reading?

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            #65
            Re: Vizio TV E470VL SMPS Flucuation Output Voltage

            No, take it out of circuit and test again, you are testing in diode mode with tv unplugged right?

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              #66
              Re: Vizio TV E470VL SMPS Flucuation Output Voltage

              .
              Attached Files
              Last edited by R_J; 01-31-2022, 08:38 PM.

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                #67
                Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                Have you checked secondary side for shorts?
                I assume no responsibility for any stupid suggestions I might post.

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                  #68
                  Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                  Zd251 was tested in diode mode with the power off. Working with small surfaced mounted components is not something I'm good at so I would like to save that for last if needed.
                  I have looked and looked and looked for shorts but no luck yet.
                  I understand that one method to test for shorts in a switch mode power supply is to use a diode as a jumper and install at the output side of the optocoupler, with the diode installed with the stripped side (I think you call that the cathode) at pin 3 (picture attached). Supposedly the shorted component will become hot within a second or two. I pre-connected my mulitimeter to ground and the 5 volt output. Assuming I did this correctly, the output voltage was 3.5 volts steady, but there was no obvious hot component. I left the power applied for approximately 10 seconds but was concerned about unknown side effects from this test procedure. I also tested for standby voltage with this method, still no standby voltage
                  Attached Files

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                    #69
                    Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                    And your voltages where stable on input side? I would think bypassing your feedback would give you over 5v. Have you tested your main caps?
                    Last edited by dskall; 02-01-2022, 11:44 AM.
                    I assume no responsibility for any stupid suggestions I might post.

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                      #70
                      Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                      I did not check the input side. The main caps are approximately 167 volts and stable

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                        #71
                        Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                        I may have misunderstood your previous question, the input side (hot side) is good and main caps are stable.

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                          #72
                          Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                          I put everything back together and tested the 5volt output and believe it or not the output was 5.25 volts stable!!! I then reinstalled the SMPS back into the TV and believe it or not it came on!!! Unfortunately before I could connect my laptop, the TV went off. I took the SMPS back out and found no output power and no voltage at Vcc but there is 167 volts at the filter caps. Upon closer inspection I found a black residue on the bottom of the board at the IC and where the SMPS was installed on the TV there was a burn mark that matched the location of the IC. I assume the IC burned up. My question how do I determine if something shorted the IC or if I did something to short it. Once while testing the IC the mulit meter probe slipped and created a spark, maybe I shorted it at that time. I have ordered a replacement IC. And to add insult to injury in de-soldering the IC for a second time I tore at least 3 of the pads. I have a fair amount of determination to fix the power supply but sometimes it feels like a mountain

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                            #73
                            Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                            I was not able to find an exact datasheet of the original IC. This is the replacement IC FSQ0465RSWDTU. I'm attaching the data sheet for it. Could someone confirm if it is a suitable replacement?

                            I'm also attaching a picture of the original IC
                            Attached Files

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                              #74
                              Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                              Your original Q0465R (bottom line) is FSQ0465RS/RB (this is the full label).
                              Attached Files
                              Last edited by lotas; 02-04-2022, 02:55 PM.

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                                #75
                                Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                                thank you!!

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                                  #76
                                  Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                                  there seems to be a big difference between RS and RB, is there a way to tell which one the original part was?

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                                    #77
                                    Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                                    The first IC I purchased may not have have been an equivalent replacement. Hopefully FSQ0565RQWDTU is. one item that is different from the original is the Continuous Drain Current Max; on the original it is 4.00 on the 565RQ it is 2.8. I don't know how the Continuous drain current works so I ask Do you think having an IC that has lesser rating for this characteristic would have a negative impact on the switch mode power supply? Data sheet attached
                                    Attached Files

                                    Comment


                                      #78
                                      Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                                      That is how much current the internal mosfet can handle not what it draws.
                                      I can't find a datasheet on the original R only the replacement which are the RS (1.8A) or the RB (3.0A) so I would pick the RB version, Or you can go to the one you ordered, it should also be fine.
                                      The problem won't be related to the current rating on the controller ic.
                                      Last edited by R_J; 02-05-2022, 01:41 PM.

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                                        #79
                                        Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                                        Thank you RJ!!!!

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                                          #80
                                          Re: Vizio TV E470VL SMPS Flucuation Output Voltage

                                          Can you tell me what the black area is at the 6 pin IC? Is it a kind of epoxy? Does it help in the removal heat? Some of it was removed when I de-solder the IC. Is it important to replace? If yes, can you tell me where to purchase. Picture attached.
                                          Attached Files

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