Samsung PS50C550

Discussion in 'The Projects Forum' started by ViperRunner, Jun 27, 2013.

  1. ViperRunner

    Thread Starter Member

    Jan 30, 2010
    50
    0
    Hey everyone!

    I am having problems with my plasma tv, so fixing it is my new project, i'll explain here what happened so far!

    It's a:
    SAMSUNG Plasma
    Model: PS50C550G1W
    Model Code: PS50C550G1WXXC
    Version: IZ02
    Manufactured in January of 2011

    I was working fine, until a couple of months ago it turned off, and when on and of with a clicking noise, and didn't answer the remote. When it was on, the screen was a dark grey that could hardly be seen.

    Well, for what i read on the symptons, it could be the power supply board, so i ordered one on ebay.

    When the psu board arriver, i mounted it on the tv, and nothing..

    Well, i gave up and took it to a local reapair shop to ask for quotes, and he told me it needed to take a Y and the t-con boards, and gave me a crazy quote for the repair that i could with the same value just buy another used one just like mine. So i paid him for the checking and left there my old psu board asking him just to check if it was ok, because for the looks of it, it should be ok, since it had just the same symptons with the new board. Some days latter i came back there to ask him about the psu board condition and he came with excuses saying he sent it to the trash, he said he understood i told him it was broken.. he was lying.. i think that for sure he used it to fix another samsung plasma that he had there fixing that when i when there with mine he told me it had a psu problem just like mine.. i should know better, in the past i already had seen he was too expensive and a cheater, but i thought i should give it another try.. ok.. that went well..

    well, i ordered new y and t-con boards and while i waited them to arrive, i took the opportunity to check the components on the old boards. for the looks of it, the Y-main board has some mosfets burned. but the t-con didnt look to have any problem, but what the hell i got one for cheap. I also checked the Y sustain buffer board as in the Tom66 video http://www.youtube.com/watch?v=51SZsfH60EY and it looked ok.

    Whell, the waiting was really hard for the boards to arrive, but when they did, the i checked the Y board for burned mosfets and everything ok, so i mounted everything up.. deception.. it kept on clicking for around 4 or 5 times and then stopped fully disconnected and only with the fixed red led just as before, but at least now the remote turns on the tv, even if she turns off after 10 or 15 seconds but hey.. that”s something.. lol..

    i took the y board out and now it has shorted mosfets.. and i think the psu has also some now..

    Some thing to consider, the Y-Main board was exactly the same part number, date and version, but had some things a bit different from my original one, mine had some more caps, can the new one coming from the uk be incompatible??

    Some measurements:

    Factory sticker values say:

    Va = 55v
    Vs = 211v
    Vsc = -185v
    Ve = 83v
    2Ve = 74

    With everyting mounted, when turning on the tv, until i had only about 10 or 15 seconds until it turned off, but even then here is the 10/15 second measurements:
    Va= nothing
    Vs= 22v
    Vg=15,5v

    without the X-board

    the same 10/15seconds on/off

    Va= nothing
    Vs= 22v
    Vg=15,5v

    without the Y and X boards (when disconnecting the Y, as the X is connected to the Y, they are both disconnected)

    Va= 56,7v
    Vs= 219v
    Vg=15,5v

    Well.. now i”m stuck without knowing what else to do or try.. and my boards, are they fixable? if i change the mosfets, check the caps and change any burned caps, will it do to fix them? or will i have to order new one's??

    Thanks for reading and for any help!

    Best regards everyone
    *
     
  2. sheldons

    Active Member

    Oct 26, 2011
    616
    101
    nonononono------what you need to do is this.....disconnect the ysus leads and zsus leads-that way both pcbs and drivers are disconnected then power on and check with your meter the ysus supply -voltage will be marked on the pcb,check at the socket on the pcb and do the same check for the zsus supply-if the voltages are present that means your main board is ok-standby switching is ok and the fault will be either the zsus or ysus and or the relevant driver pcb-reconnect the boards one at a time but switch off before connection and then switch on-if you have a fault here the screen should come up but with part of the screen blanked depending where the fault is-while you are working on this set do be aware the chassis is LIVE AT ALL TIMES so no scopes or earthed test gear to be connected unless using isolation tx or you will have a bang and a scrap set-of course the fault may also be a faulty pdp in which case its scrap....of course you do realise that these sets are not in any way built to last like a crt set-most repairs to a crt can be done to component level reliably and away the set goes and runs for another 10-15 years after already working for the same when new where due to plasma or lcd requiring pcb replacement and are crap anyway max life before throw away is 2 to 3 years....
     
    Last edited: Jun 27, 2013
  3. Patmac57

    New Member

    Jan 14, 2016
    2
    0
     
  4. Patmac57

    New Member

    Jan 14, 2016
    2
    0
    What does the Vg actually mean?
     
  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,986
    745
    Sounds like the Y board is pulling the 56V rail down.
     
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