What should the input voltage be at? Right now with the backlights flickering I have constant 21.4VDC, is that enough or is that low? If the problem is in the backlight inverters do you replace the master or slave or both or how do you know? Any insight would be helpful.
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First check if you have on screen menu and if the problem is still there if you change input source and cables.
If TV has no backlight on all inputs, then it is either inverter not supplying power to the backlight system, or the LCD panel itself. The inverter or the parts connected to the inverter are common cause for the problem. The LCD panel is not a common fault. When problem is the panel the TV is not worth repairing.
When there is an inverter problem the fault is not necessarily the inverter. The technician needs
to test the parts to find out what part is responsible. Testing is done
tracking voltage from PSU to inverter. Voltage to inverter is usually
supplied by the higher VDC line from PSU. Here broad description of how to test the three
parts: Before proceeding...
Here replacement parts for most flat panel TV models:ShopJimmy.
You are right ,the problem is in the backlight. There's a loose connection in the connector of the backlight to inverter or driver.The backlight have high voltage supply,so if the coonector is mildly loosen,it may cause of voltage drop produce and spark and over heat the connector,and totally result of loose connection.So the things you can do to fix the problem ischeck the connection of the backlight.Open the back cover and look the board,located at the center part.It has a metal cover in the board,remove the cover and check the connector of the backlight,Resolder and tightly press the connector to the inverter or driver.It is usually happen to the backlight of the LCD TV.Just fix the connection of the backlight.Try my suggestion and procedure,.Hope it will help you..Thanks..
Problem is inverter, backlight or PSU. The backlight lamps that illuminate the LCD display are flashing. This creates the "kind of strobe" effect that you see. There are several possible causes for the problem.
The lamps themselves are defective. The lamps do not fire up completely and keep flashing. The lamps are not sold alone but they are part of the LCD display. If the lamps are gone the TV is not worth repairing.
The inverter is the high voltage board that supplies the backlight lamps. If the inverter is defective it can still be replaced. Testing is done reading DC in, checking high voltage out, and using an oscillator to test the phase of the AC out signal generated by the inverter oscillator section.
PSU or main controllers may be defective. This will less common in case of flashing back-light. Test this if the inverter is OK and if the problem is DC voltage input to inverter.
Either the backlight inverter or mainboard not relaying the 5v supply to the inverter to tell it to "come on." I would check input voltage for the ps_on to the inverter and make sure it's not the main board.
could be a problem in the inverter board and the backlight lamp of the
monitor . The lamp is a cold cathode bulb it requires a high voltage
supply from the inverter board in order to light up. Like any other
bulb this lamp has a limited life span more or less 2 years of
continues lit. The inverter board is a high voltage board the power
input of this board is 24volts DC and the output is 200volts AC.The
terminal input of this board or connectors must be check because of
high voltage Corrosion and loose connections always happen that leads
to the mal function of the display or screen failure just like what
happen to your TV. Backlight lamp is installed at the top and
bottom of the screen you need to open the back cover of your TV to
check up the lamp.(make sure to unplug the TV before proceeding)
Hi,please chech does the screen of your TV lights up?during power on?if not then there might be a problem on the inverter board and the backlight lamp of the monitor .The lamp is a cold cathode bulb it requires a high voltage supply from the inverter board in order to light up.just like any other bulb this lamp has a limited life span more or less 2 years of continues lit.The inverter board is a high voltage board the power input of this board is 24volts DC and the output is 200volts AC.The terminal input of this board or connectors must be check because of high voltage corrosion and loose connections always happen that leads to the mal function of the display or screen failure just like what happen to your TV. Backlight lamp is installed at the top and bottom of the screen you need to open the back cover of your TV to check up the lamp.(make sure to unplug the TV before proceeding)..check first the test point that I mentioned then post back for your findings then will proceed to further trouble shooting.I hope this will be helpfull to you.GOOD LUCK!
This is a common problem on these plasma TV's. The problem resides in
the high voltage boards known as the X and Y Sustain boards.. You can
purchase them here for a very reasonable price: http://www.discount-merchant.com/Y-SUSTAIN-FOR-42-PLASMA-TV-PN-6871QYH036A-p/sku9510.htm
The above link is to a Y-SUS board. The X-Sus board is often the 2nd cause of failure and can be found here: http://www.discount-merchant.com/X-SUSTAIN-6871QZH041B-6870QZE017D-6871QZH052D-p/sku9509.htm
test which board is failing, you need to check voltage input to the
YSUS board first... Input should be 120V from Power supply, output
should be above 250V.. Do this test with XSUS disconnected. IF 250+V
exists, then XSUS is damaged. If not, then the YSUS is the faulty part.
This failure could be due to a backlight inverter board or the power supply is not providing the 24 volts to it.
The way to fix it is by measuring the voltages from the power supply to the backlight inverter board, if the voltage is present then the backlight inverter board is defective and will need to be replace. If the voltage is lower then 20 volts, then is a power supply failure. Click here to find the backlight inverter board.
Let me know if you need further assistance. I repair power supplies for all LCD models.