Re: LG 42LB5600-UZ No Picture, Sound OK
Thanks for your help.
To clarify was talking of replacing individual LED's verses the strip.
I have Part Number/Model Number for the Backlights / backboard assembly as T420HVF07.1
TheRic
Member
Last Activity: 01-13-2020, 10:32 PM
Joined: 04-18-2017
Location: Minster
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LG 42LB5600-UZ No Picture, Sound OK
Backgroud
I have a LG 42LB5600-UZ, The screen is dark but sound works. When doing the flashlight test I can see the picture.
Ground on Chassis
Tested the voltage at the backlight connector, it hangs at 102VDC. When I first turn on the TV, the voltage at the the backlight jumps up to about 260VDC after about 1-2 seconds, then ramps down over about 5-10 seconds down to 102VDC. I get the same voltage with the LEDs connected or not connected.
Ground on LED-
Tested the voltage at the backlight connector, it hangs at 0.01VDC. When I first turn on... -
Re: e701i-a3 no picture but backlights
Don't know about the best, but I got my T-con Board from ShopJimmy.Leave a comment:
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Re: e701i-a3 no picture but backlights
Did some testing / playing.
There are two side boards, the bottom has 2 tabs, the top has 3 tabs.
There are no components on the boards themselves, there is a chip on the the flexible tab. SO I thought if I removed the top tab from the TV AND the board it would not be sending anything bad back. Tried the test pattern, nothing changed.
SO I thought maybe it's the second tab, even though the lines were at the top. I removed 2nd from the top tab from the TV AND the board. Tried the test patterns, nothing changed....Leave a comment:
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Re: e701i-a3 no picture but backlights
You are correct that I did NOT blow the FET. Figured I had a 50/50 shot on saving the FET, more like the hassle of soldering one in.
Since the lines are just at the very top, could I just remove the top tab? Thinking then only the Top Right would be doing full duty and the others 1/2 duty. Not sure if it works that way, specially since you commented about early reports about the whole side had to be removed.
Do you know if I will know instantly if I have to remove the whole side, verses it acts up next week after...Leave a comment:
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Re: e701i-a3 no picture but backlights
Removed both ends of the bottom left corner cable. Test patterns were the same.
Re-attached both ends of the cable.
Before I fired it up to watch it blow a FET, I decided to disconnected the jumper cable from the two boards on the left. I disconnected from the lower board, so that the jumper cable is out of the equation. I now get lines across the top of the test pattern, see attachments. Not sure if this means anything. I thought I read something in this thread that were the lines are tells you which driver...Leave a comment:
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Re: e701i-a3 no picture but backlights
I have more FET's, bought several, knew better. Could try re-seating the cable. But the $100,000 question is how many times do you blow a FET after re-seating before you are 100% sure it's not that.
I disconnected the ribbon cable from the side board only, the ribbon cable is still connected to the bottom board. It was easier to disconnect the cable on the side than on the bottom. Question / clarification: You want the other end of the cable disconnected NOT a cable going to the bottom board?
I'll check out the...Leave a comment:
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Re: e701i-a3 no picture but backlights
Here are some Test Patterns: SMPTE, Indian Head, Solid Red, Solid Green, Solid Blue. The waves in the solid colors, are not on the TV. The Yellow /white in the
Solid colors I think are from the Flash or light glare, since they are not on the TV.
When the Video goes from Red to Green to Blue it takes a little over 1 sec for the color to fill in on the left edge. See RedGreen and GreenBlue image.
The Control Panel (power, volume, channel) on the lower left side behind that is the white ribbon cable I removed from...Last edited by TheRic; 05-02-2017, 07:26 PM.Leave a comment:
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Re: e701i-a3 no picture but backlights
Got the cable disconnected (for others it is right behind the control panel on the side). Picture is fine on the right side, but the left is darker and redder. It seems to be the worst at the middle and gets a little better as it gets near the left edge for some colors like green. Red washes out most of the left side.
There are no lines that I can see....Leave a comment:
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Re: e701i-a3 no picture but backlights
Got a Vizio 70" from Sams Club Special Black Friday deal several years ago. It finally went out on me a couple of weeks ago. Been reading this forum on the fix since.
Ordered a new T-con board, disconnected the right side ribbon cable, fired it up, blew the T-con board. So I ordered some MOSFET (specs from this forum), soldered one in, disconnected the two bottom cables from the T-con board, checked my voltages, most of them were within range (more on that later). Plugged in the right side cable (as you look at the front...Leave a comment:
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Re: New Members - please post your introductions here
Just found out about this site, while trying to fix my TV. I'm a computer Geek, not to mention an all around geek. Background in Electronics, Robotics, and mostly computers. First learned computers in High School on Radio Shack TRS-80, with tape recorder for storage, and I think it had 12K or memory. Having been fixing electrical and electronic items on the side for 40+ years.Leave a comment:
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