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Louie
Louie, Technician
Category: TV
Satisfied Customers: 11419
Experience:  25+ yrs. experience in the field and 5+ yrs. online, down to component level.
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I'm having some trouble diagnosing my tv problem. I have an

Customer Question

Hi I'm having some trouble diagnosing my tv problem. I have an old 47" Westinghouse LCD TV and it will not turn on. I plug it in, turn it on, the Westinghouse symbol shows on the screen for about 5-10 seconds and then the screen goes black. I tried the flashlight test and I couldn't see anything, I also have no audio I'm trying to determine what the problem would be so I can either purchase the parts or have it repaired. I'm trying to determine if it's the master and slave inverters or if it's the power supply or even needing a new backlight.
Submitted: 1 year ago.
Category: TV
Expert:  Louie replied 1 year ago.

Hi and welcome to JustAnswer,

Thank you for the question and your patience. Should you still need assistance for information purposes only...

Initially, the description of "...shows on the screen for about 5-10 seconds and then the screen goes black..." would point to a likely auto-protect mode kicking in.

As a process of elimination, determine if the power supply is fully working as it would be the most likely suspect by checking the presence and consistency of the output voltages. The expected voltages at each connector pin are normally printed on the board itself such as (but not limited to):

  • • standby +5.0V;
  • • running +5V;
  • • +12V
  • • +24V.

Post back results / observations of the above once tested.

Additionally, determine and post back the version of the power supply board; something like a 56.04419.601.

A friendly reminder; voltage measurements by its very nature requires that the unit be plugged in, attempted to be turned ON and therefore LIVE! Please exercise due care and caution.

Customer: replied 1 year ago.
I tested the power supply and everything checks to what it says the outputs on the board should be. I replaced the backlight inverters because the capacitors looked bad and I'm still having the same problem. Im starting to think it might be the mainboard or the backlight itself.
Customer: replied 1 year ago.
The board number is *****
Expert:  Louie replied 1 year ago.

The backlight would be the least likely suspect; ...if it were faulty, then there should still be audio even if when the "...the screen goes black..."

Are you able to manually turn Off the TV when the "...the screen goes black..." ?

Customer: replied 1 year ago.
I have to hold the power button down for a few seconds. But if I use the remote it works. I don't know how to access the main board so I can take it out and inspect it
Customer: replied 1 year ago.
I've also read something about some "sleep mode" I don't know what that is or if it even affects my tv. But I did have it in power saver mode before I had these problems.
Expert:  Louie replied 1 year ago.

Sleep mode would be triggered by the absence of a usable video signal but not "...5-10 seconds..."; usually much longer.

Can you provide clear picture of the back of the TV showing the different boards? Of particular interest would the main board/shielding

Customer: replied 1 year ago.
Here are the images of what it looks like to access the power supply and mainboard
Expert:  Louie replied 1 year ago.

Thanks.

A review please; what is the voltage at the BL_ON & PWR_ON pins during standby? and when attempting to turn on?

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