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Philips 42PF7320 plasma, strange problems

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    #1

    Philips 42PF7320 plasma, strange problems

    This TV had two problems. It would intermittently drop into standby mode while operating. And when the entire display area changed between scenes at once, the panel would sometimes blank out for a moment.

    After dropping into standby, the TV would need to be unplugged and replugged before it would turn on again.

    I opened the service menu and an error 11 was registered. The service manual says this is an "I2C error while communicating with the 2D/3D combfilter Columbus". Could that have just been from low voltage?

    Then the TV wouldn't turn on at all - the relays clicked twice, the red LED showed momentarily then it clicked off.

    The front LED never displayed any blink codes except for the second to last time the TV turned on the front green LED blinked infinitely.

    There are no burst capacitors on the power board (a Samsung LJ44-00101B PS-424-PH Rev0.65) nor does anything there look cooked. But about 2/5ths of the caps have subtly rounded quadrants whereas the rest are totally flat on top. Is this some manufacturing variation or the result of pressure buildup? These are Samxon KMOD caps from 2005.

    I tried unplugging everything from the power board except the mains power connector. It still clicked thrice. After that, it won't click at all now. Is this normal behaviour when the PSU is in isolation? Does this indicate blown fuses? Would it be dangerous to the TV to plug everything back in and try again?

    I found a repair tips guide for the power board (search "Philips PS- 424-PH LJ44-00101C PSU.pdf" ) that describes how to provoke the power board to display an error code, but I don't have he necessary shorting jigs and am a bit wary of trying to connect the pins directly as they are so close together.

    Could this all still be consistent with just Samwha C8059/60 failures? The power board does seem to be the root of the problem but this is unlike the difficulties it has given others.
    So I'd be thankful of any tips.
    Last edited by homerging; 12-09-2011, 06:22 AM.
    Tags: None
    #2
    Re: Philips 42PF7320 plasma, strange problems

    Subtly rounded sounds a lot like bulged to me. If they are not completely flat, they have failed, or are about to. It certainly sounds a lot like a power supply unable to cope with transient or sudden changes in loads, bad caps can cause that.
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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      #3
      Re: Philips 42PF7320 plasma, strange problems

      That would mean up to 15 capacitors in all may need replacing.

      What I would like to know is whether it's worthwhile attempting to replace these caps, that is, what concerns me is what the lack of relay clicks means and whether replacing the capacitors is likely to fix it?

      Comment

        #4
        Re: Philips 42PF7320 plasma, strange problems

        Originally posted by homerging View Post
        That would mean up to 15 capacitors in all may need replacing.

        What I would like to know is whether it's worthwhile attempting to replace these caps, that is, what concerns me is what the lack of relay clicks means and whether replacing the capacitors is likely to fix it?
        It's possible you now have a more serious problem. Can you post a picture of the power supply board? Then some tests can be highlighted.
        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.

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          #5
          Re: Philips 42PF7320 plasma, strange problems

          pic attached
          Attached Files

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            #6
            Re: Philips 42PF7320 plasma, strange problems

            Test these two resistors while the TV is off. I think they should measure 6.8 ohms each.

            Test this fuse also while off. I think it should measure less than 1 ohm.

            Also test the resistance of your meter leads - touch both probes together and note down the measured resistance.
            Attached Files
            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

              #7
              Re: Philips 42PF7320 plasma, strange problems

              Unfortunately, I do not have a meter, so I would have to get one, but I'm not sure about how to tell the good from the bad in that area over what is needed to test a power board.

              Comment

                #8
                Re: Philips 42PF7320 plasma, strange problems

                Originally posted by homerging View Post
                Unfortunately, I do not have a meter, so I would have to get one, but I'm not sure about how to tell the good from the bad in that area over what is needed to test a power board.
                A multimeter is fairly cheap. Whereabouts are you?
                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.

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                  #9
                  Re: Philips 42PF7320 plasma, strange problems

                  Test these two resistors while the TV is off. I think they should measure 6.8 ohms each.
                  The one on the left gives 6.8, the one on the right varies from 6.8 to 7.0. They both have 6.8 written on them.

                  Test this fuse also while off. I think it should measure less than 1 ohm.
                  It gives 0.1 to 0.3 if I touch the two points on the back of the PCB, and 1 to 3 if I touch the fuse directly on the front of the PCB.

                  Also test the resistance of your meter leads - touch both probes together and note down the measured resistance.
                  It jumps around alot and comes to zero.

                  Comment

                    #10
                    Re: Philips 42PF7320 plasma, strange problems

                    Ok, so the 8A fuse giving 0.1 to 0.3 probably means it is still working normally? Does the lack of relay clicks specifically mean a fuse or fuseable resistor is blow?

                    If this power supply board is effectively unrepairable, can I swap in any working LJ44-00101B / LJ44-00101C replacement powerboard, or is television model-specific setup required to supply correct and operationally safe voltages?

                    Comment

                      #11
                      Re: Philips 42PF7320 plasma, strange problems

                      The powerboard models for this TV have a cluster of dodgy 680uf 50v Samwha WB capacitors under a heatsink. Any cap that goes under it must be less than 30mm high. The only cap I can see that might be suitable and fits is the Rubycon 50ZLJ680M12.5X25.




                      Is the Rubycon ZLJ's being rated 0.025 for impedance versus 0.020 on the Samwha WB going to be a problem? In other words, is the Rubycon ZLJ an appropriate replacement?

                      Comment

                        #12
                        Re: Philips 42PF7320 plasma, strange problems

                        Should be fine. Samwha WB are crap caps and never last (possibly they lied on the spec sheet - who knows?), the power supply should work fine with the Rubycons.
                        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.

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                          #13
                          Re: Philips 42PF7320 plasma, strange problems

                          Originally posted by tom66 View Post
                          Should be fine. Samwha WB are crap caps and never last (possibly they lied on the spec sheet - who knows?), the power supply should work fine with the Rubycons.
                          Thanks, I did wonder about the accuracy about the WB specifications because apart from the load life, they're excellent.

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                            #14
                            Re: Philips 42PF7320 plasma, strange problems

                            There are number of larger 16mm diam. Samxon KMOD caps that may need replacing (680uf 100v, 47uf 350v, 100uf 160v). What I am not clear on is are there special requirements for "filter" caps or live vs cold (dc?) if these are those? Or are the likes of Rubycon ZLJ or Panasonic EE likely to be fine so long as they match ESR and ripple current specs?

                            Comment

                              #15
                              Re: Philips 42PF7320 plasma, strange problems

                              Hi there. First off, I've learned a lot from reading these forums and I wanted to to thank all the people who contribute to this site. I'm pretty new to TV repair and have had some luck in finding simple capacitor swap out jobs.

                              Now, here's my problem. I have a Philips 42" with a 5 blink red led code. The TV will power on for about 10 minutes (time varies) and then there will be a crackle and it will shut off with a 5 blink led. If you unplug it and give it some time, it can be reproduced, but not always.
                              I have visually inspected all the caps on the board (ESR meter on the way since I seem to be getting more involved in repair) and have found none to be bulging or domed.
                              After checking some voltages and matching them up with the sticker on the upper right of the chassis, everything seems normal except the Vset reading was 560v instead of the 195v it should be at! Hmm... I have a feeling that this has something to do with the problem.
                              What could be causing this? What is my next course of action in troubleshooting this board at a component level?

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                                #16
                                Re: Philips 42PF7320 plasma, strange problems

                                I forgot to mention that the power supply is the one in this thread. (LJ44-00101B) The TV is a similar model (42 PF 7220A/37B).

                                Comment

                                  #17
                                  Re: Philips 42PF7320 plasma, strange problems

                                  Originally posted by DPark View Post
                                  After checking some voltages and matching them up with the sticker on the upper right of the chassis, everything seems normal except the Vset reading was 560v instead of the 195v it should be at!?
                                  Tom66 is the plasma expert, but I can't ever recall seeing a post where voltage is 560V DC. If that reading is correct, then I would have expected many capacitors to go .
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                                    #18
                                    Re: Philips 42PF7320 plasma, strange problems

                                    Vset should be very close to Vs (180~210V), not guaranteed to be exact, but very close.
                                    A 560V Vset would burn your Y-main and buffers, so you're probably measuring it wrong...
                                    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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                                      #19
                                      Re: Philips 42PF7320 plasma, strange problems

                                      I don't think I'm measuring it wrong. I have the black probe touching the chassis and the red wire going to the little solder spot where it says "vset." Then, I turn on the power. What could I be doing wrong?

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                                        #20
                                        Re: Philips 42PF7320 plasma, strange problems

                                        Show us a picture of your multimeter.

                                        Some multimeters have low batteries and give incorrect readings, but there is no indication of the low battery indicator on the lcd screen.
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