Question about Hitachi CMP4120HDU 42 in. Plasma Television

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I have a hitachi 42'' plasma model CMP4120HDU. i can turn it on and it will be on for 2-10 mins then the display turns off but the sound is still playing. also is there a firmware update for it? how would i get it put on the tv if there is one?

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  • SMastin1 Mar 21, 2011

    i have a hitachi 42'' plasma model CMP4120HDU. i can turn it on and it will be on for 2-10 mins or sometimes hours then the display turns off but the sound is still playing. i have been told its something with the power inverter board. what would that board look like? as oppose to the power regulator board?



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  • Master
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Hi,the part that cause the common failure of plasma TV No picture just sound are the Y-sus & Z-sus circuit boards.The part in the Y & Z sus boards are call IPM.The reason is heat generated by impedance and age.I found a method to prevent this problem is by making the IPM work cooler by adding more heat sink area on to the existing heat sink.Without additional heat sink the IPM temperature measures 75 degrees C.What I learn about semi conductors failure,heat is one of them.Also mosfets inside the IPM will short and burn up.

Also there are alot of checks you would have to do on this set. If you are DIY i can give some examples of voltage checks, also you can check

Take a moment to carefully observe the Buffer "Snot" Chips

(Left Side black chips mounted on the SDR Upper and Lower PWBs).

Look very closely for burns and/or small holes in these chips.

If any defect is seen, the PWB is defective.
Replace this PWB and the Y-SUS

Make sure if you don't have any idea about this,you will need to contact and expert for help.

Posted on Mar 22, 2011

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  • Hitachi Master
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This is not the fault of firmware. It has fault in its power regulator board. After switch on your TV works normally and then gets OFF the picture while sound output is there. That means, the power regulator board is working well, but there is some trouble with the supply voltage to the video card that comes from the power inverter board interrupts. It indicates there is some loose contact in the soldering terminals of that board. If you are aware in electronics, and have a concept of soldering, take out the power inverter card, put it upside down, and resolder the suspected solder points by applying a little more solder, without making any solder shorts in between the adjecent solder terminals. Never do this work, while the set is connected on power line, as mains power first comes to this board, and then inverterd by a switching regulator circuit, and then the resulting switched output voltage is again rectified to Direct Current [DC]; and supplied ot other secitons and circuit boards of your TV. The most of the pints at the power inverter board will be 'live" and it is fatal to touch it with when it is connected to AC mains.
Firmware update must be done only if the set is fully out of control, and never switch from standby, sound trouble, picture distortion etc. There are no such problem to your plasma TV now. Moreover, care should be taken when update firmware, because, some will not match and synchronise with the present firmware it has now installed. It should be done with care and after proper guidance Hitachi. OK.

Posted on Mar 21, 2011

  • The Knight
    The Knight Mar 22, 2011

    You can identify that board be following the AC input connection, to which where it goes into the TV. It will contain four or mour bulky capacitors and 3 or more SMPS transoformenrs fitted on it. The largest wize capacitors in your TV will be fitted on it and from which you can undersand and identify it easly. Never touch it when the set is pluged to AC. All the components in it are "Live" and will be fatal to touch. keep the AC input pulled off from the AC mains and begin to work on it. OK.



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