Beko Tv PSU zz7.194p-5 (LCDPSU-3)

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  • notallbad
    Badcaps Legend
    • Oct 2012
    • 1183
    • UK

    #1

    Beko Tv PSU zz7.194p-5 (LCDPSU-3)

    Firstly apologies if this should be in the TV troubleshooting section, if necessary I shall revert back to my original thread but think the original fault has been rectified, namely stuck in Service Mode so reset the Eeeprom.

    Anyway, the PSU is as named above and the problem appears to be the 24v rails from power up start off low and gradually rise (backlights flickering) until 22.4v or so has been reached whereas at which point the inverters power up the backlights fully.
    This occurs when switched on for the first time after being disconnected from power for a lengthy period of time, after the first power up it will start up near enough straight away if powered down then up straight away, but if left for a short period and then powered up it will turn on (rise to 22.4v quicker) but still with a delay with flickering backlights.

    It seems that this would sound very much like a capacitor issue but not entirely sure, hence why I'm here asking for confirmation and perhaps a little help troubleshooting.

    With both 24v connectors removed the 24v rail rises straight away no problem regardless of when the Tv was last powered on, but with a load connected, i.e inverters or 2 x 12v car bulbs in series, the 24v rails slowly build up to 22.4v.
    There are two 24v rails, one for the inverters and one for audio, both rails do the same as explained above.
    I think this pretty much eliminates the inverter boards to be at fault but not sure the SSB can yet be eliminated.

    If someone could help me track down the culprit causing this I would be eternally grateful, I don't want to replace all the caps and possibly volt regs as my soldering isn't great and the parts are hard to source so if it could be narrowed down to just a couple of possible components that would be great.

    Thanks for your help/advice!

    I should add that the Tv once on does fully function.
    Last edited by notallbad; 05-05-2013, 06:55 PM.
  • Khron
    Badcaps Legend
    • Sep 2006
    • 1350
    • Finland

    #2
    Re: Beko Tv PSU zz7.194p-5 (LCDPSU-3)

    Some (clear) pictures might hep Preferably ones with a good view of the secondary (specifically the brands and series of the caps).

    "For good measure" you could consider (also) replacing the small "start-up caps" next to the PWM chips on the primary with some "good brand" ones; they should be in the range of 47-100uF / 35-50v.
    Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

    Comment

    • ben7
      Capaholic
      • Jan 2011
      • 4059
      • USA

      #3
      Re: Beko Tv PSU zz7.194p-5 (LCDPSU-3)

      Originally posted by notallbad
      Firstly apologies if this should be in the TV troubleshooting section, if necessary I shall revert back to my original thread but think the original fault has been rectified, namely stuck in Service Mode so reset the Eeeprom.

      Anyway, the PSU is as named above and the problem appears to be the 24v rails from power up start off low and gradually rise (backlights flickering) until 22.4v or so has been reached whereas at which point the inverters power up the backlights fully.
      This occurs when switched on for the first time after being disconnected from power for a lengthy period of time, after the first power up it will start up near enough straight away if powered down then up straight away, but if left for a short period and then powered up it will turn on (rise to 22.4v quicker) but still with a delay with flickering backlights.

      It seems that this would sound very much like a capacitor issue but not entirely sure, hence why I'm here asking for confirmation and perhaps a little help troubleshooting.

      With both 24v connectors removed the 24v rail rises straight away no problem regardless of when the Tv was last powered on, but with a load connected, i.e inverters or 2 x 12v car bulbs in series, the 24v rails slowly build up to 22.4v.
      There are two 24v rails, one for the inverters and one for audio, both rails do the same as explained above.
      I think this pretty much eliminates the inverter boards to be at fault but not sure the SSB can yet be eliminated.

      If someone could help me track down the culprit causing this I would be eternally grateful, I don't want to replace all the caps and possibly volt regs as my soldering isn't great and the parts are hard to source so if it could be narrowed down to just a couple of possible components that would be great.

      Thanks for your help/advice!

      I should add that the Tv once on does fully function.
      Hm, sounds like a small capacitor on the psu is bad, or maybe pfc isn't working (if it has pfc at all). Could you please get us some pics of the psu? Thanks!
      Muh-soggy-knee

      Comment

      • notallbad
        Badcaps Legend
        • Oct 2012
        • 1183
        • UK

        #4
        Re: Beko Tv PSU zz7.194p-5 (LCDPSU-3)

        Some photos which will hopefully be useful.



        Uploaded with *************



        Uploaded with *************



        Uploaded with *************

        Comment

        • notallbad
          Badcaps Legend
          • Oct 2012
          • 1183
          • UK

          #5
          Re: Beko Tv PSU zz7.194p-5 (LCDPSU-3)

          A couple of the smaller caps are Jamicomm and a few of the larger caps just say RF from what I can see with them in situ.
          None are bulging or leaky.

          Looking at the top of the board from left to right the electrolytic caps are rated:
          1 680uF 35v
          2 1000uF 16v
          3 680uF 35v
          4 680uF 35v
          5 1000uF 25v
          6 680uF 35v
          7 22uF 25v

          Looking at the bottom of the board from left to right the electrolytic caps are rated:
          1 680uF 35v
          2 680uF 35v
          3 680uF 35v
          4 10uF 50v
          5 150uF 450v
          6 10uF 50v
          7 10uF 25v
          8 10uF 50v
          Last edited by notallbad; 05-06-2013, 07:26 PM.

          Comment

          • notallbad
            Badcaps Legend
            • Oct 2012
            • 1183
            • UK

            #6
            Re: Beko Tv PSU zz7.194p-5 (LCDPSU-3)

            I believe this to be a Filter, its connected between the mains input / power button and the PS b/d. Just thought I should include it in case it has any bearing on the fault and assist troubleshooting.



            Uploaded with *************

            Comment

            • notallbad
              Badcaps Legend
              • Oct 2012
              • 1183
              • UK

              #7
              Re: Beko Tv PSU zz7.194p-5 (LCDPSU-3)

              Cheers Ben7, looks like you were spot on!

              Fixed and all working now!

              Comment

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