Re: No backlight, with sound Samsung lcd LN46B640R3F
What else could cause all the back lights to go out at the same time? Could some bad component cause all of them to go out?
sandersen
Member
Last Activity: 09-25-2014, 07:15 PM
Joined: 07-20-2014
Location: La Puente, CA
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Re: No backlight, with sound Samsung lcd LN46B640R3F
I'm assuming you meant cn1803 shown in the picture.
I measured pin 1 (12V) at 12.89VDC
Pin7 (LD) at 11.5VDC
Pin8 (LD) at 11.5VDC...Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
What voltages should I expect at drive 1 & 2?Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
@budm-No ever since the set went dark I can't see any flash at all. Turned it on by jumping the ps and sb in a dark room and saw nothing.Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
@budm the values I got were
Pin1 vcc 10.49VDC
Drive 1 0VDC .01 AC
Drive 2. 0VDC. .009 AC
My common was on gnd pin 4 I'm not sure if that was correct?
Also for the life of me I could not find C1804 I think it's the blue one near the fuse above the markings cy1811s....Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
@stj here is the inverter board...Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
Sorry picture is rotated. Second pin from the top, on the right is where I measured.Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
Went ahead and measured the voltage at the ena pin on lx6503 (second to last pin on the left side of the picture). Voltage was 2.56VDC ref to chassis ground and the same voltage was on cap labled c1837....Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
So the inv-on voltage when the sb and ps pins are jumped should be at 3.8 VDC . I assumed it should be 5.1 VDC?Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
Measured correctly this time. I measured 384 VDC on both capacitors.Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
Will check voltage correctly tomorrow. Thanks for the help.Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
You are correct I did use chassis ground. Should have measured voltage across the caps. Don't know what I was thinking???Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
When I put my leads together I do read .5 ohms. Also checked in diode mode there is continuity.Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
Here is the second fuse on the top left. The two caps I measured are the on the right....Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
These are the two fuses I checked. Both had 5 ohm resistance so they are good. The caps that I measured are cp802 and cp803 both, with a jumper on ps and sb, measured only 62VDC.
First fuse....Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
Here is the right side. Can't post all at once?...Leave a comment:
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Re: No backlight, with sound Samsung lcd LN46B640R3F
Budm
These are the pictures of the back. Left side first....Leave a comment:
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No backlight, with sound Samsung lcd LN46B640R3F
Looking for help on LCD tv. Tv was working fine then all of a sudden all goes dark. Sound still works can still see image on screen with flashlight test, just no backlight.
So far I have checked fuses at power supply both were good,all capacitors looked good as far as I could tell (no bulges). Tried unplugging the main board from the power supply to force the backlight on. Backlight did not turn on. Jumped the SB pin and PS pin at the power supply and checked voltages at all the pins. All looked good 5.1V pins read 5.21V, 13V pins read 12.94V. The pins I'm not sure about are INV-ON... -
Re: New Members - please post your introductions here
Hello all,
My name is Dan and I'm a Mechanical Engineer. I work in the packaging industry building and designing machines. I like to learn new things and am a DIY kinda guy.
Thanks!Leave a comment:
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