Backlights turning off -- No luck even after replacing inverters. Help.


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Backlights turning off -- No luck even after replacing inverters. Help.

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celltechexpress
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Jun 15, 2015, 8:33 PM

Post #1 of 4 (978 views)
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Backlights turning off -- No luck even after replacing inverters. Help.	Can't Post

Hello,
I've got a Sanyo DP42848. It was brought in because the backlights would turn off after a second or two of turning on the Tv. I thought to myself "Backlight inverters." I take it back, turn off the lights and indeed, I can see the screen when I put the flashlight to the screen.... Replace the backlight inverters, no joy. I bought 2 other inverters just incase the ones i got were bad, still no joy. Thought maybe it was the power supply, still no joy. Now, I didn't think they were the bulbs because I could still see the image on the screen when I shine a flashlight to it in the dark... Is that the only thing left that could be the issue?

I would really appreciate the help. This is my last resort as I can't figure it out. Thanks.

Mike
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jts1957
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Jun 15, 2015, 11:34 PM

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Re: [celltechexpress] Backlights turning off -- No luck even after replacing inverters. Help. [In reply to]	Can't Post

Seeing an image on screen with a flashlight has NOTHING to do with whether the bulb(s) are good (or bad).

Inverter board needs:
Voltage from the power supply board;
Enable or turn on (BLON) voltage from the Main board;
and dimming voltage from the Main board.
ALL three must be present at the correct levels before the bulb(s) will light.

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Location: Far, Far Away

celltechexpress
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Jun 16, 2015, 4:23 PM

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Re: [jts1957] Backlights turning off -- No luck even after replacing inverters. Help. [In reply to]	Can't Post

Thank you for your reply. I am new in the TV Repair side of things...

I've replaced the inverters and the power supply, so suppose I will try a new main board as well and see if that does the trick.

If I am getting a good image for the 2 seconds that the screen shows, would that indicate that my bulbs are good and that the issue is with one of the 3 boards?

Thank you, I will respond back with information.

Mike
Cell-Tech

jts1957
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Jun 16, 2015, 6:10 PM

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Re: [celltechexpress] Backlights turning off -- No luck even after replacing inverters. Help. [In reply to]	Can't Post

1) Voltage from the power supply board?
2) Enable or turn on (BLON) voltage from the Main board?
3) and dimming voltage from the Main board?
Measure and record each, at plug-in / and at turn-on / and after the screen goes dark.

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If I am getting a good image for the 2 seconds that the screen shows, would that indicate that my bulbs are good?

NOT necessarily.

-------------------------
Location: Far, Far Away

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