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Proview 3200 no backlights

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    #21
    Re: Proview 3200 no backlights

    From the pictures, it looks like the 24v is generated by one transformer, the 12v is generated by another transformer to the right of the 24V transformer.
    Can I see good clear pictures straight shot of the bottom side of the board so I can trace the connections? Also a straight shot of the top side.
    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


      #22
      Re: Proview 3200 no backlights

      Originally posted by budm View Post
      From the pictures, it looks like the 24v is generated by one transformer, the 12v is generated by another transformer to the right of the 24V transformer.
      Can I see good clear pictures straight shot of the bottom side of the board so I can trace the connections? Also a straight shot of the top side.
      Will do tonight.
      I did test the caps and the 2 power resistors in the 24v section that powers the inverter, they test fine.
      36 Monitors, 3 TVs, 4 Laptops, 1 motherboard, 1 Printer, 1 iMac, 2 hard drive docks and one IP Phone repaired so far....

      Comment


        #23
        Re: Proview 3200 no backlights

        Originally posted by budm View Post
        From the pictures, it looks like the 24v is generated by one transformer, the 12v is generated by another transformer to the right of the 24V transformer.
        Can I see good clear pictures straight shot of the bottom side of the board so I can trace the connections? Also a straight shot of the top side.
        Best I can do for today:
        Attached Files
        36 Monitors, 3 TVs, 4 Laptops, 1 motherboard, 1 Printer, 1 iMac, 2 hard drive docks and one IP Phone repaired so far....

        Comment


          #24
          Re: Proview 3200 no backlights

          OK I'm convinced now that it is indeed a power supply issue.

          The supply will only come up with full 24v occasionally, and only when brought up with no load. Once it's up and stable it seems to be able to deliver a fair amount of current.
          I even got it running, then plugged in the inverter and got all backlights on. once.

          So, I'm not to well-versed on SM power supplies. I'm assuming if it can output several amps sometimes, it's not a regulator or FET issue, more likely a sense issue.
          Are the sense resistors the 1W resistors on the component side? Or are some of the surface mount resisors on the solder side involved?
          36 Monitors, 3 TVs, 4 Laptops, 1 motherboard, 1 Printer, 1 iMac, 2 hard drive docks and one IP Phone repaired so far....

          Comment


            #25
            Re: Proview 3200 no backlights

            Yes it is the power supply problem, plus the blown fuse for the inverter board PWM IC.
            I try to trace out the connections on the power supply board, but it is a little time consuming since I have to look at the top side, then the bottom side to figure out the circuits.
            How much is the replacement power supply?
            That big green resistor on the top side by the MOSFET on the heatsink that drive the 24V transformer is the Source current sensing resistor, there should be a small surface mounted resistor that is also connected to the Source pin that will be connected back the I sense pin the SMPS IC.
            Last edited by budm; 11-04-2012, 05:32 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


              #26
              Re: Proview 3200 no backlights

              Originally posted by smason View Post
              OK I'm convinced now that it is indeed a power supply issue.
              Well I measured a bunch of the resistors/diodes that are connected to the 24v side, nothing obvious. I looked at the datasheet of one opf the pwm chips, and decided that without service information, and as much as I love a challenge, and to learn something, screw it, life's too short, and I don't have the time to dedicate to it. I ordered a supply off of Ebay for $40.00

              We shall see.
              36 Monitors, 3 TVs, 4 Laptops, 1 motherboard, 1 Printer, 1 iMac, 2 hard drive docks and one IP Phone repaired so far....

              Comment


                #27
                Re: Proview 3200 no backlights - Update it's alive!

                Originally posted by smason View Post
                screw it, life's too short, and I don't have the time to dedicate to it. I ordered a supply off of Ebay for $40.00

                We shall see.
                Finally got the supply. It shipped in 2 days to San Diego, a relative was going to bring it on a plane, but cancelled the trip. SO good old USPS took a 2 weeks and way too much money to get here.

                I popped the supply in, and fired it up, backlights!
                Re-assembled it (holy sh*t what a pain in the ass) and nope, not working.

                Disassembled it, hmm inverter is unplugged. I had it assembled upside down so the cables were too short. Had it worked it would have been funny wondering why the hell the picture was upside down. re-re-assembled it, even more of a pain, and it's on test and working!

                I feel bad for "board swapping" when it's probably a $0.49 part, but didn't have the time or the brain power to focus on it. The owner will be happy.
                36 Monitors, 3 TVs, 4 Laptops, 1 motherboard, 1 Printer, 1 iMac, 2 hard drive docks and one IP Phone repaired so far....

                Comment


                  #28
                  Re: Proview 3200 no backlights - Update it's alive!

                  Originally posted by smason View Post
                  It shipped in 2 days to San Diego, a relative was going to bring it on a plane, but cancelled the trip. SO good old USPS took a 2 weeks and way too much money to get here.
                  Depending on the service, 2 weeks from the USA to Canada is excellent. I always try to get the cheapest shipping rate so I'm used to waiting 2 to 4 weeks.

                  At least you didn't get screwed by UPS/FedEx for brokerage charges of $35 or more.
                  --- begin sig file ---

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                  We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

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                  Comment


                    #29
                    Re: Proview 3200 no backlights

                    Originally posted by budm View Post
                    Check that small black fuse that looks like a resistor by the inverter connector to the right, it should have 15 or 20 printed on the top. Common failure for this board.
                    It looks something like this:
                    http://s807.photobucket.com/albums/y...ps27a023ac.jpg
                    You can use 0.22, .33, or 0.47 Ohms 1/4 Watt through hole resistor, one of its leg is connected to the 24VDC input, it is used to supply the power to the PWM IC.

                    Hey, I know this is an old thread, but.....

                    THANK YOU, BUDM!!!!!!

                    This was the fix for my unit!!! I checked all the larger
                    white fuses, and they were all fine, but this little black
                    fuse was it! Luckily, I have plenty of spare boards to
                    steal parts from, as I know most of you do as well!!


                    THANK YOU, THANK YOU, THANK YOU!!!

                    DID I MENTION, THANK YOU???

                    Comment


                      #30
                      Re: Proview 3200 no backlights

                      I am glad it is just simple to repair, thanks for the feed back.
                      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


                        #31
                        Re: Proview 3200 no backlights

                        I have this tv and the power board was showing 3-5v pulse on the 12v line heating the board with a hair dryer it would power on normal

                        I found a tiny cold solder joint on one of the ic chips on the bottom of the power board pushing on it would get power up and running.

                        The solder looked perfect but it has been working perfect since I put some flux and re-soldered it.

                        just gos to show even perfect looking solder can be cracked.

                        anyway good luck hope this may help some one
                        Attached Files

                        Comment


                          #32
                          Re: Proview 3200 no backlights

                          i KNOW This is an old post, But hope I can still get some advice, My power supply puts out 12.1 volts across the 12V side but only 23.5 V across the 24V side. Is this okay or within limits? My Backlight comes on for 2 seconds and then goes off, I have repaired an open fuse at F1 on the inverter board, It showed 20 on the top 1A 76V, Before repairing this fused link, I did not get any backlight at all. I am suspecting the inverter board itself went bad somewhere, But as I understand it the fuse is suppose to protect it from things like that. where to go next.

                          Thank you in advance for your valued reply's and knowledge, I am very glad you all are here.
                          39 Soldering Iron burns And Counting

                          Comment


                            #33
                            Re: Proview 3200 no backlights

                            2 seconds to black can be a number of problems the first thing i would check are the transformers on the inverter board one might have a faulty winding is there a part number on them to find the resistance checks.

                            Comment


                              #34
                              Re: Proview 3200 no backlights

                              I have not seen a cap leak from the side like this, is this leaking or is it some kind of sticker residue?
                              Attached Files
                              39 Soldering Iron burns And Counting

                              Comment


                                #35
                                Re: Proview 3200 no backlights

                                Part number on Inverter is Board VIT70002.00, I320B1-24-V02-L3C1
                                39 Soldering Iron burns And Counting

                                Comment


                                  #36
                                  Re: Proview 3200 no backlights

                                  well worth changing those two capacitors in my opinion the plastic covering looks like its got hot and shrunk on the left one two.

                                  Comment


                                    #37
                                    Re: Proview 3200 no backlights

                                    you were right on the money on those transformers, two of them were open. I had some old ones that had comparable resistance, and Bingo, we got in living color. Thank you
                                    39 Soldering Iron burns And Counting

                                    Comment


                                      #38
                                      Re: Proview 3200 no backlights

                                      cool thats good i would also change those two capacitors though use panasonic fm/fr/fc if you can.Good job you had spare inverter transformers ive just picked up a boxed 22in toshiba set that uses one inverter transformer and that has a open secondary winding so just had to order one.

                                      Comment

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