2007 Insignia LCD 32" - Large Capacitor on PSU squeeling

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  • RollaGrad
    Member
    • Dec 2013
    • 11
    • United States
    #1

    2007 Insignia LCD 32" - Large Capacitor on PSU squeeling

    Hi all,

    I was given an Insignia lcd-32-07 because it wouldn't power off one time and then it wouldn't turn on. Originally after receiving it, the television would power on after pressing the power button numerous times on and off. (During this time, there was clicking noises when I would hold down the power button) While it eventually power's up, when plugged into the outlet a high pitched noise is heard coming from the power supply (more specifically the large 450V 150uf capacitor. If the TV is turned on the high pitched noise gets louder.

    I checked voltages on the PSU and am getting the standby voltage of 3.3V.
    My large capacitor, which appears to be producing the whine maintains 170V when in standby, and ramps to around 350-400V when powered on as expected. None of my capacitors look bulged, but I went ahead and replaced the large capacitor in hopes of this solving the issue.

    Unfortunately, the TV had the same issues so I went ahead and ordered a new power supply after seeing no blown caps on the main board. The new power supply arrived today and I installed it. To my dismay, immediately after plugging it in the squealing started (although a softer whine). The TV does now turn on after one press of the power button and stay on (picture looks fine) but the capacitor continues to produce a high pitched noise, becoming louder when turned on and when turned off after being on, starts into an cycling stage of squealing (sounds like the high pitched noise is charging, then resets and repeats)

    At this point, I am fairly sure there is a downstream issue. I recently graduated from an engineering school in Electrical Engineering, so I have a some background in electronics. However, I am stumped. Does anyone have suggestions on where I should go from here?

    Thanks so much! I've been troubleshooting for quite some time.

    Here are pictures of the Power Supply Board and TV
    Attached Files
    Tags: None
    • NihonNoir
      Badcaps Veteran
      • Jan 2014
      • 231
      • US
      #2
      Re: 2007 Insignia LCD 32" - Large Capacitor on PSU squeeling

      This won't help you, but I happened to come across this video of a squealing power supply after replacement when looking up my own TV. http://www.youtube.com/watch?v=Itw0LKtwGjY

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA
          #3
          Re: 2007 Insignia LCD 32" - Large Capacitor on PSU squeeling

          Are there any labeling on those connectors on the output side of the 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

            • RollaGrad
              Member
              • Dec 2013
              • 11
              • United States
              #4
              Re: 2007 Insignia LCD 32" - Large Capacitor on PSU squeeling

              Thanks for the replies! NihonNoir, my situation isn't the same type of buzzing you have in that video. Mine is a distinct high pitch whine coming from the large PSU capacitor upon even plugging in the power cord.

              Bud, yes there are labels on the power supply output. I've included pictures of all outputs. I have noticed that once I unplug the cable containing the 3.3V, 2 - 12V, 5V, 9V pins and plug in the power cord. The whining is not there, just a very very slight hum, which I think to probably be normal. I know the 3.3V is a standby voltage in order to be able to turn the TV on, but do you have any insight as to what might the other voltages are for or the possible issue here?

              I checked the main board for blown caps, only to find that, visually, they all looked fine and not bulged. I have attached pictures below (Sorry for the poor quality) There is a picture that shows the aforementioned cable unplugged, and also where it is plugged into the main board.

              Thanks again!
              Attached Files

                Comment

                • Ltank
                  Badcaps Veteran
                  • Jun 2013
                  • 776
                  • USA
                  #5
                  Re: 2007 Insignia LCD 32" - Large Capacitor on PSU squeeling

                  The timing capacitor in the circuit that affects the drive circuits to the transformers. Check ESR on caps or for a bulging capacitor. The capaitor affects the freguency. The frequency is too low thus the squeeling. This is on the PS board Get a pic of the tag from rear of set to get the correct Service manual or power supply schematic. How about a pic of the top side ( component side) of the PS?
                  Last edited by Ltank; 01-24-2014, 05:00 PM. Reason: correction

                    Comment

                    • selldoor
                      Slow Learner
                      • Dec 2010
                      • 7870
                      #6
                      Re: 2007 Insignia LCD 32" - Large Capacitor on PSU squeeling

                      That board looks to have a fine selection of mediocre to bad caps- cant see them properly but if populated with JH or ltec 85degree caps they have probably dried up.
                      Please upload pictures using attachment function when ask for help on the repair
                      http://www.badcaps.net/forum/showthread.php?t=39740

                        Comment

                        • RollaGrad
                          Member
                          • Dec 2013
                          • 11
                          • United States
                          #7
                          Re: 2007 Insignia LCD 32" - Large Capacitor on PSU squeeling

                          Ltank,
                          I will attach the TV tag when I get home. Thanks for the responses!

                          Selldoor,
                          Yeah I know for sure there are a handful of JH caps. Perhaps I should try a recap. Would they possibly cause the large cap to whine?

                            Comment

                            • Ltank
                              Badcaps Veteran
                              • Jun 2013
                              • 776
                              • USA
                              #8
                              Re: 2007 Insignia LCD 32" - Large Capacitor on PSU squeeling

                              Normally a transformer whines when opeating at a lower frequency. A dried cap would have very high ESR. In a oscillator circuit I guess they will vibrate. They should not vibrate when used in a steady dc circuit.

                                Comment

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