Insignia NS-39L700A12 backlight transformer high pitched wine

Collapse
X
Collapse
 
  • Page of 2
  • Time
  • Show
Clear All
new posts
Previous 1 2 template Next
  • MikeRWK
    Senior Member
    • Jun 2017
    • 121
    • Canada
    #21
    Re: Insignia NS-39L700A12 backlight transformer high pitched wine

    Originally posted by R_J
    I asked for the emitter & collector voltages to see if the ic's had the proper vcc, Since you did'nt post it here, I suggest you look up the ic's datasheet and see if they are correct.
    I meant to post pics, here they are.
    Attached Files

    if you find these attachements useful please consider making a small donation to the site

      Comment

      • R_J
        Badcaps Legend
        • Jun 2012
        • 9624
        • Canada
        #22
        Re: Insignia NS-39L700A12 backlight transformer high pitched wine

        If the 18v is stable then it should be ok, if it is slow to build up to 18v then there is a problem. To be sure of the voltage I would need the part numbers on N504 & N501

          Comment

          • MikeRWK
            Senior Member
            • Jun 2017
            • 121
            • Canada
            #23
            Re: Insignia NS-39L700A12 backlight transformer high pitched wine

            Originally posted by R_J
            If the 18v is stable then it should be ok, if it is slow to build up to 18v then there is a problem. To be sure of the voltage I would need the part numbers on N504 & N501
            Here are pictures of N504 and N501. I forgot to mention the Emitter voltage at standby is 21.5v
            Attached Files

            if you find these attachements useful please consider making a small donation to the site

            Last edited by MikeRWK; 01-25-2021, 12:11 AM.

              Comment

              • MikeRWK
                Senior Member
                • Jun 2017
                • 121
                • Canada
                #24
                Re: Insignia NS-39L700A12 backlight transformer high pitched wine

                Should the voltage on the emitter fluctuate like this with the tv off? https://streamable.com/x4o0z1

                  Comment

                  • R_J
                    Badcaps Legend
                    • Jun 2012
                    • 9624
                    • Canada
                    #25
                    Re: Insignia NS-39L700A12 backlight transformer high pitched wine

                    18 volts is fine for the main & pfc ic's The emitter voltage will be higher in standby because the transistor is turned off. So is the vcc voltage in standby 21.5v or is iI changing? In standby, N503 is in burst mode so the vcc voltage could be changing, or the capacitor for that voltage is bad. The standby ic also uses this voltage but only requires it to be around 15 volts (stop voltage is 8.1v) in standby
                    Last edited by R_J; 01-25-2021, 12:55 PM.

                      Comment

                      • MikeRWK
                        Senior Member
                        • Jun 2017
                        • 121
                        • Canada
                        #26
                        Re: Insignia NS-39L700A12 backlight transformer high pitched wine

                        I replaced all the electrolytic caps with known good ones and it's still got the high pitched noise coming from the transformer. What causes transformer whine?

                          Comment

                          • R_J
                            Badcaps Legend
                            • Jun 2012
                            • 9624
                            • Canada
                            #27
                            Re: Insignia NS-39L700A12 backlight transformer high pitched wine

                            L601 is NOT a transformer, it is just a coil (inductor) In this case it is used to boost the led voltage, Is the base supply voltage ok and clean? If the supply is not filtered properly, there can be a beat frequency between the main supply transformer frequency and the led driver frequency.
                            Or it could just be due to loose windings or cracked core in the coil. Are the backlights ok and does the whine change with if you change the backlight level?
                            Last edited by R_J; 01-25-2021, 04:14 PM.

                              Comment

                              • MikeRWK
                                Senior Member
                                • Jun 2017
                                • 121
                                • Canada
                                #28
                                Re: Insignia NS-39L700A12 backlight transformer high pitched wine

                                Originally posted by R_J
                                L601 is NOT a transformer, it is just a coil (inductor) In this case it is used to boost the led voltage, Is the base supply voltage ok and clean? If the supply is not filtered properly, there can be a beat frequency between the main supply transformer frequency and the led driver frequency.
                                Or it could just be due to loose windings or cracked core in the coil. Are the backlights ok and does the whine change with if you change the backlight level?
                                The backlights flicker, the inductor noise changes when I push on it

                                  Comment

                                  • MikeRWK
                                    Senior Member
                                    • Jun 2017
                                    • 121
                                    • Canada
                                    #29
                                    Re: Insignia NS-39L700A12 backlight transformer high pitched wine

                                    I've decided to scrap the tv it was free anyways.

                                      Comment

                                      • R_J
                                        Badcaps Legend
                                        • Jun 2012
                                        • 9624
                                        • Canada
                                        #30
                                        Re: Insignia NS-39L700A12 backlight transformer high pitched wine

                                        Originally posted by MikeRWK
                                        The backlights flicker, the inductor noise changes when I push on it
                                        There could be a fault with the led's causing the problem, carefully remove the lcd panel & diffusers and see if there are some bad led's.

                                          Comment

                                          Previous 1 2 template Next

                                          Related Topics

                                          Collapse
                                          • ohren
                                            Original Xbox 1.0 PSU: Foxlink FTPS-0002 Rev. B. — 12 V low, 5 V high — transformer?
                                            by ohren
                                            Hello!

                                            I'm looking at an original Xbox PSU: Foxlink ftps-0002 rev. B. The 12 V output is too low, and the 5 V output is too (?) high. Unfortunately I don't have an oscilloscope but only a DMM for diagnosis.

                                            Measured voltages with no load:

                                            After rectifier diodes
                                            12V: 6.17 V
                                            5V: 5.67 V

                                            Secondary transformer pins AC measurement (really don't know if this says anything)
                                            12V: 2-2.5 V
                                            5V: 1.04 V


                                            I also have another (working) Xbox psu from Delta. The same measures there, in order, being: 10.79,...
                                            03-18-2023, 10:33 AM
                                          • learnmore
                                            Help choosing replacement transformer for Levoit 600S SMPS
                                            by learnmore
                                            Hello Community,

                                            I'm attempting to repair the SMPS on a Levoit 600S air purifier. The transformer is likely open. It has six pins. 2 pairs on the primary side (one pair tested open) and 1pair of legs on the secondary side. Legs on the secondary side are spread wide apart (end-to-end). I've circled them in blue. Dimentons of the transformer are 22x23mm. Marking on the transformer are EE16 1.9mH-B. Fuse for the powerboard is fuse 250V 3.15A. I've been unable to find an exact match and I'm hoping for some help here to find a suitable replacment.

                                            Peace
                                            LM...
                                            11-04-2025, 09:35 AM
                                          • JDC
                                            (SOLVED) - Funai FW55D25F - High Pitched Squeal Upon Power-on.
                                            by JDC
                                            Issue: Funai FW55D25F - High Pitched Squeal Upon Power-on.

                                            Solution: Replace C3208 and C3209 on main board. These are surface mounted capacitors. Values unknown so I just used same physical size capacitors from a donor board.
                                            02-01-2022, 10:25 AM
                                          • mikey5791
                                            Is it possible for transformer substitution?
                                            by mikey5791
                                            Hi all,
                                            Got this local made DC power supply (12/14V) given free as the transformer has melted. There is no marking or indication to identify what type or rating of transformer used.
                                            Fyi,. I had a busted autogate mainboard with transformer with marking 13-0-13 . Is this the 13v dc type transformer?
                                            My questions are
                                            1. How do i test to see if the transformer is in good working condition?
                                            2. Can this transformer (marking 13-0-13) be used to replace the melted transformer on the DC power supply?
                                            Hope you guys understand what i was asking. My intention is...
                                            11-03-2022, 02:11 AM
                                          • Briesmith
                                            Can High Side damage on an SMPS get across the Transformer to the Low Side?
                                            by Briesmith
                                            I have a blown smps and I am looking for some reassurance as to the amount of diagnosis I have to do. It blew the instant I plugged it in not under any load.

                                            As you can see from the attached pix, the damage is located around the main or bulk capacitor (since removed for testing) and the resistor array/network that drives it (the bunch of SMD components to the left of the YAMAHA YC775 AMPS logo). The burn mark on the frame clearly shows the pins of the capacitor. And, for the avoidance of doubt, there is no way the board could have contacted the frame, it was correctly mounted on...
                                            05-06-2023, 09:36 AM
                                          • Loading...
                                          • No more items.
                                          Working...