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    #1

    phillips 42pf7320a/37 blinking screen+sparkles

    hey guys working on this phillips 42" plasma..

    i actually have two of these, got them in a bulk deal...

    It has red and blue snow on the screen, that flashes. Thats all i can get it to do after power up. also looks like some oil slicking going on as well.

    ok heres the deal.. i have one totally torn apart, one mostly togther but was missing ysus and buffer boards. I opted to try to fix the one that(was) mostly togther.

    Took the loose ysus and buffers from the other set, the lower buffer board has one chip burning hot.. swapped with another buffer board, different chip running hot, swap with lucky#3.. this one runs cool so i think were set there for now..

    swapped ysus boards, no change. Swap xmain boards, no change. Swap video input boards no change. changed the little board that all the ribbon cables meetup at, no change.

    Power supply is working. wtf is going on here. I might have to call these a lost cause because who knows wtf is any good here..
    Last edited by cadillacman; 04-24-2011, 12:38 AM.
    Tags: None
    #2
    Re: phillips 42pf7320a/37 blinking screen+sparkles

    I need more information, and you can do this two ways.

    1. Provide the part numbers of the Y-Sustain, upper, and lower Y-buffers.

    2. Provide a good top-down picture of the Y-sustain.

    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

      #3
      Re: phillips 42pf7320a/37 blinking screen+sparkles

      i will most definately get some pics later tonight...

      THis set could be running fine with just screen issues, theres no input button just menu, bieng the menu is unseeable i cant go any firther to see if it has audio or not..

      Comment

        #4
        Re: phillips 42pf7320a/37 blinking screen+sparkles

        Ok here we go. Wish me luck. If you want any other specific shots ill be happy to take them.
        Attached Files

        Comment

          #5
          Re: phillips 42pf7320a/37 blinking screen+sparkles

          These aren't worth fixing. Your problem is bad buffers and y-main. All 3 will need to be replaced if you want to get these going. Parts will cost almost as much as the tv is worth. Even if it is only one board that is bad the others will not last much longer if you only replace the bad board. A week or two at most.

          Comment

            #6
            Re: phillips 42pf7320a/37 blinking screen+sparkles

            Check these out:

            Link 1
            Link 2

            You can send off the y-sus and buffers to be rebuilt for ~$130 or you can repair them yourself.

            Comment

              #7
              Re: phillips 42pf7320a/37 blinking screen+sparkles

              Originally posted by daimoku View Post
              Check these out:

              Link 1
              Link 2

              You can send off the y-sus and buffers to be rebuilt for ~$130 or you can repair them yourself.
              that is frickin rad!!!!!!

              thank you for that. i will definately give that a check. One of those ysus boards has a newer hybrid on it and some of the solder pads are missing from a krappy desolder job.. i guess i should check that and see if mabye its repairable with some trace work.


              seems to me these hybrids are a common failure point( i have another no name onitor ill be posting about soon with a bad hybrid)

              what number hybrids should i be stocking up on?


              edit: ok ive tested both buffer boards for shorts and i have none, which means theres at least a chance they will live. I chcked the other two lower buffer boards i have that were running hot, they are both shorted so i did confirm my suspicion that they are bad.

              Now the y sustain ive had in here is checking good, im not finding a short. However, i do suspect perhaps something in the hybrid has gone open instead.. who knows lol
              Last edited by cadillacman; 04-25-2011, 12:46 AM.

              Comment

                #8
                Re: phillips 42pf7320a/37 blinking screen+sparkles

                man they need to open up my time limit so i can edit posts whenever.. this 30 minuite rule really messes me up!

                Ok ive checked over both ysus boards i have, both have all good fuses that i can see, both have hybrids that are checking ok(no shorts)


                There are some heat sinks over some big transistors.. should i unsolder those sinks to check those transistors for shorts?

                Comment

                  #9
                  Re: phillips 42pf7320a/37 blinking screen+sparkles

                  Originally posted by cadillacman View Post
                  man they need to open up my time limit so i can edit posts whenever.. this 30 minuite rule really messes me up!

                  Ok ive checked over both ysus boards i have, both have all good fuses that i can see, both have hybrids that are checking ok(no shorts)


                  There are some heat sinks over some big transistors.. should i unsolder those sinks to check those transistors for shorts?
                  I can confirm what daimoku said. Those panels are the pits. One buffer blowing will short a drive transistor on the Y-Sustain. The drive transistors are relatively inexpensive; it's replacing them that might be a challenge - they are are mounted next to one another.

                  It's not necessary to remove the heat sink. All transistors have the sources connected together, and all have the drains connected together. The gates are driven from a common point with a series resistor. By connecting one lead of a DMM to the drain and probing the gates of the transistors you can identify the shorted one. Coppell explains it here. By using a long thin probe you can touch the individual gate leads without pulling the heat sink.

                  Note this auction. The guy will provide a repaired Y-sustain AND test your buffers. I've contacted him, he runs the buffers in a working TV. This leads to a question - if a shorted buffer will blow a $7.00 transistor on the Y-Sustain, how can he afford to test buffers for free? One possible conclusion is he has some method of protecting the transistors. I'd like to know what it is.

                  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

                    #10
                    Re: phillips 42pf7320a/37 blinking screen+sparkles

                    Fused ( modified board ) used for testing. He may use a low amp fuse on v input or fuse on transisiter. I have done this when I have no idea what I am doing ( most of the time).

                    He may just ohm them then fire them with his test y board.

                    I have done this with delco radios long ago. (lots of extra boards helps)

                    Comment

                      #11
                      Re: phillips 42pf7320a/37 blinking screen+sparkles

                      ok. BILL- what legs whould i be ohming between on those transistors? center and right(3rd leg)? i understand ill be checking at traces where thse are connected mabye not directly on them due to space issues.

                      cadi- thanks for chiming in on my posts as well you guys rock!

                      Im going to temorarily shelf this.. I will be back!

                      I WILL get back on it because if these are the suck, i better get good at fixing them. Plus i have two of the damn things, would be nice to build one.. if i have a bad transistor i can always rob one off of the other ysus(yes after testing it heh)...

                      ive got a set of "good" buffers on this set and another good top buffer board, so IF i can fix the ysus board before it kills them again, i might just be in business. I think ill add a fan on those buffers, seems like a horrid common failure point on those..

                      Just picked up another load of 7 tvs tonight.. im on a frickin roll man. I dont know what ive done but all of a sidden it seems good things are coming my way. Its nice change let me tell you.

                      Im learning ALOT along the way( mabye a career change too????)and this is helping me pay some debt, it will be nice to shut up these annoying debt collectors let me tell ya.

                      Its about time for me to make some sort of hot air rework station or pick one up used... im good with the old iron but working in surface mount with one sucks.
                      Last edited by cadillacman; 04-25-2011, 08:05 PM.

                      Comment

                        #12
                        Re: phillips 42pf7320a/37 blinking screen+sparkles

                        DamnifIremember. The pinouts of mosfets are pretty well standardized, but I don't remember the standard. The blog entry I linked to earlier lists the part number of the transistor. From that you can get the datasheet, which shows the pinout. That's what I did.

                        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

                          #13
                          Re: phillips 42pf7320a/37 blinking screen+sparkles

                          Originally posted by cadillacman View Post
                          Its about time for me to make some sort of hot air rework station or pick one up used
                          Dave Jones over at the eevblog just did a 23 minute video blog review of the Atten 858D Hot Air Rework Review (episode 167).

                          Arrgh, apparently I didn't pay enough attention as per this thread by Krankshaft

                          https://www.badcaps.net/forum/showpo...25&postcount=7
                          Last edited by retiredcaps; 04-25-2011, 10:41 PM.
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                          Comment

                            #14
                            Re: phillips 42pf7320a/37 blinking screen+sparkles

                            pulled the heat sinks off of both boards for ease of testing. No shorts on any of those large transistors. Where do i go from here?

                            Comment

                              #15
                              Re: phillips 42pf7320a/37 blinking screen+sparkles

                              These TVs are a pain. It is most likely a buffer problem. The buffers do not have to be shorted to be bad. I have had bad buffers that have read anywhere from 6 ohms to 270 ohms across the inputs and outputs. That does not mean that the Y-main is good though. I have seen bad SMD diodes, resistors, and ICs cause these problems.

                              Comment

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