LG 42PX5D 42 in. Plasma HDTV Logo
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Stephen Scott Posted on Feb 11, 2014

Lg 42px5d how do I test the main board for operation

Turns on green light 5sec later clicks and goes back into standby mode all caps look fine

  • Stephen Scott
    Stephen Scott Feb 21, 2014

    how do I test the y dustain board and which board is it I presume the main bord is the one with the av hdmi ect then you have a board above that and then there is a board on each side if them two boards could you tell me which one it is

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1 Answer

larry lease

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  • Contributor 56 Answers
  • Posted on Feb 18, 2014
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Probably not main board but a short on the y- sustain board or a bad power supply

  • Stephen Scott
    Stephen Scott Feb 21, 2014

    how do I test the y dustain board and which board is it I presume the main bord is the one with the av hdmi ect then you have a board above that and then there is a board on each side if them two boards could you tell me which one it isFeb 21, 2014

  • larry lease Feb 21, 2014

    Hi Stephen, Y Sus is big board on the left side. you have to remove it and check for shorted components with a DVM (digital volt meter) If you have no electronic experience this is probably over your head, but you can pull the board and have someone check it for you.

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3 Related Answers

freetek

Steve Allison

  • 5569 Answers
  • Posted on Sep 29, 2009

SOURCE: TV will not power on.

The clicking you hear is a relay that connects, then disconnects the AC to prevent fire or further damage.

If it just fails to turn on, the main power supply is probably at fault and without some technical background and a couple of test instruments, you will not be able to do the repair yourself.
What you can do though is; unplug the set, let it stand overnight or at least several hours, remove the back panel and look for a separate board with mostly larger components on it; it will have a ferrite core transformer on it and several larger capacitors which are cylindrical and mounted vertically to the board.

Before touching anything inside, especially on that board, allow several hours to be safe since the larger capacitors can hold a painful voltage charge for some hours.

There are likely two power supplies, a main (larger) and possibly a separate supply for the plasma display.
Without inspecting your set it is difficult to determine which may have failed since the high voltage supply may use an output from the main supply.
If you see signs of overheating such as discoloration of the board material, it may not be repairable but if you can find a part number on the board, you might be able to buy the power supply and install it yourself.
If there are no signs of heat damage to the board, there may be companies offering to repair it as a subassembly instead of repairing the whole set which could be much more expensive.
If you choose to replace it or have it done, the power supply still may not be at fault since most are capable of switching on and off if a downstream problem is causing an overload.

Not easy to diagnose without having made a few measurements first.

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Paul

  • 381 Answers
  • Posted on Mar 26, 2010

SOURCE: LG 42 Plasma try's to turn on but just goes back into "stanby" ?

Check to see if you get Va and Vs voltages from the power supply. There should be some wires running to the y-sus. A couple of those wires will be labeled va and vs. Are they present? There will be a sticker stuck to the panel somewhere telling you what they should be.

Anonymous

  • 28 Answers
  • Posted on May 19, 2010

SOURCE: my lg plasma tv stays on standby

is you already change the power board,is possible
your y board is out...is a big board on the left side of the tv

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The clicking you hear is a relay that connects, then disconnects the AC to prevent fire or further damage.

If it just fails to turn on, the main power supply is probably at fault and without some technical background and a couple of test instruments, you will not be able to do the repair yourself.
What you can do though is; unplug the set, let it stand overnight or at least several hours, remove the back panel and look for a separate board with mostly larger components on it; it will have a ferrite core transformer on it and several larger capacitors which are cylindrical and mounted vertically to the board.

Before touching anything inside, especially on that board, allow several hours to be safe since the larger capacitors can hold a painful voltage charge for some hours.

There are likely two power supplies, a main (larger) and possibly a separate supply for the plasma display.
Without inspecting your set it is difficult to determine which may have failed since the high voltage supply may use an output from the main supply.
If you see signs of overheating such as discoloration of the board material, it may not be repairable but if you can find a part number on the board, you might be able to buy the power supply and install it yourself.
If there are no signs of heat damage to the board, there may be companies offering to repair it as a subassembly instead of repairing the whole set which could be much more expensive.
If you choose to replace it or have it done, the power supply still may not be at fault since most are capable of switching on and off if a downstream problem is causing an overload.

Not easy to diagnose without having made a few measurements first.
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