Announcement

Collapse
No announcement yet.

Phillips 50PF7220A/37B - seven red flashing lights.

Collapse
X
Collapse
 
  • Page of 2
  • Filter
  • Time
  • Show
Clear All
new posts
Previous 1 2 template Next
    #1

    Phillips 50PF7220A/37B - seven red flashing lights.

    My 50" plasma, a Phillips 50PF7220A/37B, has the seven red flashing lights.

    I bought this as a factory refurb 5 years ago and had no problems up to 18 months ago when I lost picture and sound, I don't remember if I got a constant or red flashing light but I opened up the back, checked the fuse next to the power input, it had blown and replaced it. It worked again.

    Couple of days ago it stopped working mid session. Red flashing light so I unplugged the power, left it for 30 minutes or so and more in hope than expectation I plugged it back in and it worked. Woo Hoo.

    My joy was short-lived as the fallowing day it stopped again and this time no amount of power off/power on would resurrect it. Opened it up and found that one end of the fuse holder had melted (See first photo) I can't tell if the fuse had blown as the end cap came off as I levered it out of the holder. I realize now that I should have checked first but be kind I'm new to this.

    I have replaced the fuse holder and put in a new fuse, a SLOW 250VAC 8A 5X20 As I had had the foresight to get 2 when the original had blown but I still get the seven red flashing lights. I've had a good look at the tops of the caps and none look blown to my untrained eye. Other than replacing the component immediately adjacent to the fuse holder that has heat marks on it (haven't done that yet) I'm not sure where to proceed.

    FYI I can follow directions, well I like to think I can, I'm reasonably competent with a soldering iron and know how to check continuity with a meter.

    https://www.badcaps.net/forum/attach...1&d=1324754924
    Attached Files
    Stolen Sig: I want my own Law, like Ohm, Murphy and Cole.
    Tags: None
    #2
    Re: Phillips 50PF7220A/37B - seven red flashing lights.

    Sounds like some primary side component has gone bad, like a power MOSFET or the bridge rectifier. You'll need to remove the power board and test all major power components, or buy a new power board if you can find one. Posting detailed pictures of the underside of the power board would be helpful. Good luck.
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

    Comment

      #3
      Re: Phillips 50PF7220A/37B - seven red flashing lights.

      Originally posted by tom66 View Post
      Sounds like some primary side component has gone bad, like a power MOSFET or the bridge rectifier. You'll need to remove the power board and test all major power components, or buy a new power board if you can find one. Posting detailed pictures of the underside of the power board would be helpful. Good luck.
      I have removed the power board and can post a picture of the underside. Know of any source for new boards in the event this one is beyond repair?



      Thanks for taking the time to respond on Christmas Eve.
      Attached Files
      Stolen Sig: I want my own Law, like Ohm, Murphy and Cole.

      Comment

        #4
        Re: Phillips 50PF7220A/37B - seven red flashing lights.

        I need a photo with a higher resolution; I want to be able to read the individual lettering on the board.

        Generally when you get an extreme failure like that, it's very good, because it means the fault is usually one single component which has had enough. And that's a simple repair.

        It's Christmas now .
        Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
        For service manual, schematic, boardview (board view), datasheet, cad - use our search.

        Comment

          #5
          Re: Phillips 50PF7220A/37B - seven red flashing lights.

          1) Your bridge rectifier may be what I circled in red. It should start with BD101 or BR101 on the pcb board. Number the pins 1, 2, 3, and 4. You can perform this test "in circuit".

          Measure the resistance between pins 1-2, 1-3, 1-4, 2-3, 2-4, and 3-4. Any reading less than 30 ohms suggests a short and warrants desoldering and verifying out of circuit.

          2) Your power mosfet is likely a 3 pin IC and starts with "Q" and mounted to a heatsink.

          3) Your pics can be up to 2000x2000 resolution and 2MB. This allows us to see more and makes identifying components easier.

          BTW, please do not post inline. We can click on the thumbnails to view the images.

          edit: tom66 beat me by 1 minute regarding #3.
          Attached Files
          Last edited by retiredcaps; 12-24-2011, 06:36 PM.
          --- begin sig file ---

          If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

          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.

          Please do not post inline and offsite as they slow down the loading of pages.

          --- end sig file ---

          Comment

            #6
            Re: Phillips 50PF7220A/37B - seven red flashing lights.

            Originally posted by tom66 View Post
            I need a photo with a higher resolution; I want to be able to read the individual lettering on the board.

            Generally when you get an extreme failure like that, it's very good, because it means the fault is usually one single component which has had enough. And that's a simple repair.

            It's Christmas now .
            Thanks. I read the FAQ's and downsized the image only to realize that I could have left it a lot larger.

            I hope this revised one helps but if you need an enlargement of a particular portion of the board let me know.

            Forgot the five hour time difference to Doughnut City, sorry.
            Attached Files
            Stolen Sig: I want my own Law, like Ohm, Murphy and Cole.

            Comment

              #7
              Re: Phillips 50PF7220A/37B - seven red flashing lights.

              Originally posted by retiredcaps View Post
              1) Your bridge rectifier may be what I circled in red. It should start with BD101 or BR101 on the pcb board. Number the pins 1, 2, 3, and 4. You can perform this test "in circuit".

              Measure the resistance between pins 1-2, 1-3, 1-4, 2-3, 2-4, and 3-4. Any reading less than 30 ohms suggests a short and warrants desoldering and verifying out of circuit.

              2) Your power mosfet is likely a 3 pin IC and starts with "Q" and mounted to a heatsink.

              .....
              The component you circled is at D8006 on the circuit board and is sandwiched between a large and small heatsink. I'll see if I can find a link to a service manual with a circuit diagram.

              I'm going to do the testing tomorrow when there might be a little less distraction.

              Thanks so far.
              Stolen Sig: I want my own Law, like Ohm, Murphy and Cole.

              Comment

                #8
                Re: Phillips 50PF7220A/37B - seven red flashing lights.

                Originally posted by Spock View Post
                The component you circled is at D8006 on the circuit board and is sandwiched between a large and small heatsink.
                They are usually long black rectangular in shape. Like the last item in this photo

                http://upload.wikimedia.org/wikipedi...iode-photo.JPG
                --- begin sig file ---

                If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                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.

                Please do not post inline and offsite as they slow down the loading of pages.

                --- end sig file ---

                Comment

                  #9
                  Re: Phillips 50PF7220A/37B - seven red flashing lights.

                  Originally posted by retiredcaps View Post
                  They are usually long black rectangular in shape. Like the last item in this photo

                  http://upload.wikimedia.org/wikipedi...iode-photo.JPG
                  Thanks, that's the one as far as I can tell without desoldering it.

                  Counting the pins from nearest to the power inlet I get.

                  1-2 .666 Ω

                  1-3 1.3 Ω

                  1-4 .681 Ω

                  2-3 105 Ω

                  2-4 .845 Ω

                  3-4 49.3 Ω

                  When I take the readings they are tending to rise very slowly by a hundredth of an ohm, is that normal. I'm using a Craftsman Digital Meter 82369.

                  Sorry for the delay in responding, life got in the way.

                  Next step desolder and test again?
                  Stolen Sig: I want my own Law, like Ohm, Murphy and Cole.

                  Comment

                    #10
                    Re: Phillips 50PF7220A/37B - seven red flashing lights.

                    Originally posted by Spock View Post
                    When I take the readings they are tending to rise very slowly by a hundredth of an ohm, is that normal.
                    Probably. Things measured in circuit are not 100% reliable, but they give a good indication.

                    I'm using a Craftsman Digital Meter 82369.
                    We don't see too many clamp meters. I'm thinking of getting one myself.

                    Sorry for the delay in responding, life got in the way.
                    No worries. It happens to all of us.


                    Next step desolder and test again?
                    Yes.
                    --- begin sig file ---

                    If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                    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.

                    Please do not post inline and offsite as they slow down the loading of pages.

                    --- end sig file ---

                    Comment

                      #11
                      Re: Phillips 50PF7220A/37B - seven red flashing lights.

                      Desoldering help needed. The bridge rectifier I'm trying to desolder is sandwiched between two aluminum heatsinks. The smaller heatsink is screwed to the larger one with the bridge rectifier between them. The large heatsink is attached to a pair of two legged clips that slide into it and the clips are soldered to the board.

                      I've desoldered the bridge rectifier but I cant move it until I desolder the heatsink clips. When I try and desolder the clips, the heatsink is doing its job too well and I'm having a problem getting the solder to melt. I'm concerned that I'm going to damage the board by overheating it so my question is :- Is there a technique for desoldering these clips?

                      I cant see any way to remove the clips from the heatsink but I could cut the legs off the clips but then there is the problem of finding replacements ....

                      HELP PLEASE.
                      Stolen Sig: I want my own Law, like Ohm, Murphy and Cole.

                      Comment

                        #12
                        Re: Phillips 50PF7220A/37B - seven red flashing lights.

                        I'm no desoldering expert, but I have heard some people use a heat gun to warm up the bottom part of the pcb to make desoldering easier.

                        Post a picture so people know what you are dealing with as well.
                        --- begin sig file ---

                        If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                        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.

                        Please do not post inline and offsite as they slow down the loading of pages.

                        --- end sig file ---

                        Comment

                          #13
                          Re: Phillips 50PF7220A/37B - seven red flashing lights.

                          Pictures as requested:-

                          Pic # 010 is the clip showing the side sliding into slots on the large heatsinks.

                          Pic # 011 Shows both large and small heatsink. The dark shadow between them is the bridge rectifier.

                          Pic # 012 Is the underside of the PCB with the legs of clip.
                          Attached Files
                          Stolen Sig: I want my own Law, like Ohm, Murphy and Cole.

                          Comment

                            #14
                            Re: Phillips 50PF7220A/37B - seven red flashing lights.

                            Does your present iron melt the solder, even a little bit? If it does, a product called Chip-Quik will work. It forms a low melt alloy with solder.

                            What wattage iron are you using? I wouldn't tackle this with anything less than a 40 watt iron; 60 might be better.

                            PlainBill
                            For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                            Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                            Comment

                              #15
                              Re: Phillips 50PF7220A/37B - seven red flashing lights.

                              Originally posted by PlainBill View Post
                              Does your present iron melt the solder, even a little bit? If it does, a product called Chip-Quik will work. It forms a low melt alloy with solder.

                              What wattage iron are you using? I wouldn't tackle this with anything less than a 40 watt iron; 60 might be better.

                              PlainBill
                              I have 2 irons, a 30W and a 45W Radio Shack desoldering iron (see below). The 45W will melt the solder a little so I'll look for some Chip-Quik. Thanks.
                              Attached Files
                              Last edited by Spock; 01-09-2012, 06:25 PM. Reason: Image went missing !!
                              Stolen Sig: I want my own Law, like Ohm, Murphy and Cole.

                              Comment

                                #16
                                Re: Phillips 50PF7220A/37B - seven red flashing lights.

                                Thanks to a good application of Chip-Quik I have managed to remove the heatsink and bridge rectifier (picture below). Retested with results below:-

                                1-2 .66 Ω

                                1-3 18.0 Ω

                                1-4 20.0 Ω

                                2-3 12.6 Ω

                                2-4 13.0 Ω

                                3-4 13.7 Ω

                                A little different from the readings I got when the component was soldered to the board but more importantly, now what?
                                Attached Files
                                Last edited by Spock; 01-15-2012, 04:46 PM. Reason: Changed Picture
                                Stolen Sig: I want my own Law, like Ohm, Murphy and Cole.

                                Comment

                                  #17
                                  Re: Phillips 50PF7220A/37B - seven red flashing lights.

                                  Your readings definitely indicate a short circuit. You will need to replace the bridge rectifier with one of the same type. Now, please test the primary transistor(s) to determine whether they need replacement as well. It's pretty rare for a bridge to blow by itself, but being sandwiched between two heatsinks like that it might have failed due to the heat alone.
                                  Originally posted by PeteS in CA
                                  Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                                  A working TV? How boring!

                                  Comment

                                    #18
                                    Re: Phillips 50PF7220A/37B - seven red flashing lights.

                                    Can you redo the test on diode mode? It definitely looks shorted.
                                    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                                    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                                    Comment

                                      #19
                                      Re: Phillips 50PF7220A/37B - seven red flashing lights.

                                      Originally posted by tom66 View Post
                                      Can you redo the test on diode mode? It definitely looks shorted.
                                      1-2 .428 v

                                      1-3 .428 v

                                      1-4 .747 v

                                      2-3 OL

                                      2-4 .410 v

                                      3-4 .408 v

                                      Nothing between pins 2 & 3.
                                      Stolen Sig: I want my own Law, like Ohm, Murphy and Cole.

                                      Comment

                                        #20
                                        Re: Phillips 50PF7220A/37B - seven red flashing lights.

                                        To test a bridge rectifier with the diode test, you should get 8 results because you have 4 diodes. It helps if you look at your bridge rectifier and the symbols and compare it to this

                                        http://upload.wikimedia.org/wikipedi..._rectifier.jpg

                                        You want to test each diode in both directions. One direction should be between 0.3 and 0.7V and the other direction should be 0L for a good diode.
                                        --- begin sig file ---

                                        If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                                        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.

                                        Please do not post inline and offsite as they slow down the loading of pages.

                                        --- end sig file ---

                                        Comment

                                        Previous 1 2 template Next
                                        Working...
                                        X