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Samsung PS42C451B2D won't turn on

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    #1

    Samsung PS42C451B2D won't turn on

    Hi all!

    I've got a Samsung PS42C451B2D 42inch Plasma I'm having issues with.

    Full disclosure: I've probably caused these issues myself, as I have very limited component level electronics experience. Now, onto the story

    Was originally getting the red sparklies/snowing issue that seems to be common with older PDP units. Through reading info on this site, I (correctly) determined the problem was most likely out of spec Y-sus voltages.

    Now, I tried to test the voltages using a multimeter. I began by testing on the PSU board between a point labeled VS-TP and the metal casing of the back of the screen. This resulted in a massive spark and a bang, and a scorch mark where I touched the negative terminal of the multimeter to the metal casing. Needless to say, I needed to change undies after that.

    After that scare, I decided I would rather not try testing any further voltages and just play around with the potentiometers to see if I could make anything better.

    I began by playing changing the VS-ADJ and VA-ADJ pots on the PSU board. This didn't seem to make any difference on the picture. I then had a crack at the Yfr and Yrr pots on the board on the lower left hand side (I believe this is the Y-sus board?) This improved the red snow issue, so I tweaked them until everything looked great.

    I put the TV all back together, and enjoyed a few weeks of trouble free viewing. Then, occasionally, the TV would stop showing picture, however sound will still be fine. Turning the TV off and then back on again straight away would rectify the issue. This would happen every now and then, without any pattern. Sometimes it would be fine for hours with no issue, other times it would happen after 10 minutes

    Then a couple of days ago, the TV just started refusing to turn on. The power LED is on, however when I try to switch the TV on, I can hear relays clicking, and then click off again straight away. The TV doesnt play its little power-on jingle or anything. I have not gotten the TV to turn on at all since this started happening. I've unplugged the unit from the wall for 24 hours etc, but no luck.

    I've pulled the case off the back to see if there was any obvious issues, but could not see any blown caps or fuses or anything out of the ordinary.

    Can anyone give advice on what I should be checking? I assume my earlier messing around with the pots on the PSU has something to do with the issues I'm seeing now. I'm hesitant to go poking around with a multimeter unless someone can tell me exactly what I should be touching with it to test properly.

    Thanks in advance for any help!
    Tags: None
    #2
    Re: Samsung PS42C451B2D won't turn on

    So going back to when you filled your pants, my first question is what brand of multimeter are you using?

    What was the meter set to before you completed the cct and had the fireworks display..?

    Comment

      #3
      Re: Samsung PS42C451B2D won't turn on

      Brand is a Digitech multimeter from Jaycar. http://www.jaycar.com.au/productView.asp?ID=QM1500

      I honestly cannot remember what setting it was on, but if I was going to do the testing again, I'd put it on V 1000 (which is actually what the product picture shows on the jaycar website)

      Comment

        #4
        Re: Samsung PS42C451B2D won't turn on

        Originally posted by Osiris_S13 View Post
        Brand is a Digitech multimeter from Jaycar. http://www.jaycar.com.au/productView.asp?ID=QM1500

        I honestly cannot remember what setting it was on, but if I was going to do the testing again, I'd put it on V 1000 (which is actually what the product picture shows on the jaycar website)
        Yeah, seriously I'd try to get something better than that. don't forget your hanging onto the other end if that thing is substandard electrically.

        Unless you were in the top range, that would have been overlimit in the 200V dc

        If you selected current by mistake, that's the same putting a short cct.

        Chances are one of the boards was on the way out anyway. These are known to blow the Xmain. There is a firmware upgrade for this model.

        Have also read failed Y-buffer and ymain can be damaged by that and/or the xmain as it is connected to it.

        My advice would be to replace, x,y & ybuffer all at once. Is the meter still alive?

        Comment

          #5
          Re: Samsung PS42C451B2D won't turn on

          Yeah it is still alive, I would have thought it would have blown the meter for sure, but I've since been using it to test stuff on a microcontroller setup I'm playing with.

          Not sure how a firmware update would help me at the stage I'm at, and I'm not even sure it would be worth replacing all the boards at this stage.

          Was really hoping it was going to be something I could rectify on the PSU, but if not I might have to investigate getting a new set

          Comment

            #6
            Re: Samsung PS42C451B2D won't turn on

            Originally posted by Osiris_S13 View Post
            Yeah it is still alive, I would have thought it would have blown the meter for sure, but I've since been using it to test stuff on a microcontroller setup I'm playing with.

            Not sure how a firmware update would help me at the stage I'm at, and I'm not even sure it would be worth replacing all the boards at this stage.

            Was really hoping it was going to be something I could rectify on the PSU, but if not I might have to investigate getting a new set
            you could try and check the voltages but they won't stay up with the x & y disconnected and definitely not with them connected faulty.

            you could set the meter to diode test/buzzer and have a poke around the xmain to see if any of the transistors are shorted. on the heatsink on the xmain the transistor at either end are the same, check across those legs and see if shorted.

            If you're patient you may be able to get the boards from the US cheap enough.

            I got lucky and landed all 3 for under a $100. I still have a y buffer spare which cost me more than the x and Y boards?

            There's a seller on ebay here that has the 3 for $180 which is steep compared to O/S.

            The firmware is what you want to upgrade after you fix it, no it won't help immediately with the situation.

            Comment

              #7
              Re: Samsung PS42C451B2D won't turn on

              Disconnect the PSU from all the other boards.--Remove ALL the plugged wires from the PSU

              Jumper using a 470 ohm to 1K resistor, STDby 5V to PS-On.

              Attach Vs-On to Earth/Gnd on same multi-way socket. (All these are on the small multi-way on bottom right-hand corner of PSU

              Attach 100W 240V bulb between the Vs output and Gnd (Vs Supply socket on PSU).

              Power up PSU--just plug in power-lead to mains.

              Lamp should light if PSU is good. Set Vs volts to whatever it says on the panel. Check and adjust Va in same manner.
              TELEFIX

              How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
              http://www.irf.com/technical-info/appnotes/an-1088.pdf
              PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

              Comment

                #8
                Re: Samsung PS42C451B2D won't turn on

                You can get delivered from Shopjimmy $140 USD, usually pretty fast the 3 boards, they'll be out of brand new TVs.

                I can't think of any repair shop that would come close to that figure. About $150 AUD at the moment.

                https://www.youtube.com/watch?v=gh1n_ELmpFI
                Last edited by tw2005; 04-18-2014, 02:11 AM.

                Comment

                  #9
                  Re: Samsung PS42C451B2D won't turn on

                  Hmm, just had a quick look and Shopjimmy doesnt seem to have any for this model...

                  Originally posted by Alastair E View Post
                  Disconnect the PSU from all the other boards.--Remove ALL the plugged wires from the PSU

                  Jumper using a 470 ohm to 1K resistor, STDby 5V to PS-On.

                  Attach Vs-On to Earth/Gnd on same multi-way socket. (All these are on the small multi-way on bottom right-hand corner of PSU

                  Attach 100W 240V bulb between the Vs output and Gnd (Vs Supply socket on PSU).

                  Power up PSU--just plug in power-lead to mains.

                  Lamp should light if PSU is good. Set Vs volts to whatever it says on the panel. Check and adjust Va in same manner.
                  Seems like a bit too involved with messing around with a live power supply for my level of experience in this area. Any other ideas to test that don't involve this?

                  Comment

                    #10
                    Re: Samsung PS42C451B2D won't turn on

                    Originally posted by Osiris_S13 View Post
                    Hmm, just had a quick look and Shopjimmy doesnt seem to have any for this model...



                    Seems like a bit too involved with messing around with a live power supply for my level of experience in this area. Any other ideas to test that don't involve this?


                    If you searched by model- no but if you search the part numbers yes. Change the model to PN42C450

                    http://www.shopjimmy.com/catalogsear...PN42C450B1DXZA

                    You could backprobe the Vsus and see if it comes up with both the X & y mains disconnected but you'd have to have the meter reading it as you turn on because it will come up briefly then shutdown because the logic board will detect a fault.
                    Attached Files
                    Last edited by tw2005; 04-21-2014, 07:01 PM.

                    Comment

                      #11
                      Re: Samsung PS42C451B2D won't turn on

                      Originally posted by tw2005 View Post
                      If you searched by model- no but if you search the part numbers yes. Change the model to PN42C450

                      http://www.shopjimmy.com/catalogsear...PN42C450B1DXZA
                      Great, thanks! I'm assuming those boards will fit, but I'll confirm model numbers later.

                      So you'd reccommend replacing the following
                      x-main http://www.shopjimmy.com/samsung-bn9...main-board.htm

                      y-main http://www.shopjimmy.com/samsung-bn9...main-board.htm

                      and y-buffer? (I could only see E buffer and F buffer boards on there)

                      Everything else (PSU, Logic/Main board etc) should still be okay?

                      Comment

                        #12
                        Re: Samsung PS42C451B2D won't turn on

                        Found these. This is where I got my parts from.

                        I'd contact them and see if they can combine postage othere wise $15 USD per item but won't find anything cheaper. Surprised he has no Ymains since the X is the most common failure.

                        Y buffer $16

                        http://www.paylesscomponents.com/rca...92-01739a.html

                        X main $16

                        http://www.paylesscomponents.com/vio...41-08591a.html

                        At worst $67 AUD plus

                        Ymain $52

                        http://www.ebay.com.au/itm/RCA-42PA3...item1c3f5df242

                        Note he has another listing USED, you can see the dust on it and this one NEW pulled from new TV damaged in transit.

                        $120

                        replacing all 3 may be overkill and maybe it's justthe X, but I'm not able to help you probe it in hope.

                        I went down this path because of all the dramas I've read of peopl swapping just one board and blowing the good board because of another bad one.

                        It's just not worth the risk given the cost and time to get the parts.

                        Comment

                          #13
                          Re: Samsung PS42C451B2D won't turn on

                          Originally posted by Osiris_S13 View Post
                          Great, thanks! I'm assuming those boards will fit, but I'll confirm model numbers later.

                          So you'd reccommend replacing the following
                          x-main http://www.shopjimmy.com/samsung-bn9...main-board.htm

                          y-main http://www.shopjimmy.com/samsung-bn9...main-board.htm

                          and y-buffer? (I could only see E buffer and F buffer boards on there)

                          Everything else (PSU, Logic/Main board etc) should still be okay?
                          there's 3 listings, they've labelled them y scan,

                          SJ is usually quicker, if you want to save some bucks I've given you alternate.

                          Is everyelse ok, I don't know, original desription sound like typical X or Y issues.

                          Did you damage anything with the sparks, probably not.

                          I've given you the fast track guide to read.

                          I'd try and confirm correct voltages .

                          Is the PDP panel bad? I don't know that either.

                          It's a reasonable gamble it should work, worst case you sell the good boards as a package and then the broken TV on Ebay.

                          Comment

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