Hi All, I've had some great successes with repairing several displays with the help of the members here.
I'm currently troubleshooting a Samsung UN60H6300AF with a backlight issue. Upon powering up, the backlight flashes once for a fraction of a second. I can see the on-screen display with a flashlight.
I've attached photos of the PSU board, and can provide more photos if needed. I have an auto-ranging DMM and very basic knowledge of circuitry.
Can someone recommend the tests used to determine if the problem is either the driver circuit or the LED strips...
gustagen
Senior Member
Last Activity: 08-09-2023, 05:24 PM
Joined: 05-02-2011
Location:
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Samsung UN60H6300AF no backlight, brief flash at power up
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VIZIO E50-C1 spotty / blotchy backlight?
Hi everyone, I've repaired several TVs with the help of the friendly folks here.
I rescued a VIZIO E50-C1 from the curb yesterday. I've had it running for several hours and it seems to work great, except for some cosmetic issues involving the backlight. I performed a factory reset and set the picture mode to 'Standard.' Backlight is 70%, 'auto brightness control' is off, and 'active LED zones' is off.
For the attached photo, I adjusted the camera settings to accentuate the issue.
My main concern is the area at the bottom of the screen with the distinct border.... -
Re: VIZIO M50-C1, powers on, no backlight, no picture
I got impatient waiting to borrow a DMM, so I cleaned up the mainboard and reinstalled it. I found a suitable replacement for the missing screw in the upper left corner.
I used a butane torch to heat the areas of the large black heatsink above the two processors, and the TV powered up! It's been playing YouTube for 15 minutes without issue, but we'll see how long this "repair" lasts.
Thanks again for pointing me toward the common BGA issue, neilc6!
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Re: VIZIO M50-C1, powers on, no backlight, no picture
I've been looking at used mainboards for sale and many of them look as ugly as the one in this set.
I'm also beginning to think this is not the original mainboard. I noticed earlier that this board has several connectors that go unused in this M50-C1, like CN203, CN211, CN212, and even an extra T-Con connector. Perhaps my board is a replacement from a larger M-series model?
Replacements I'm seeing for the M50-C1 have solder pads for these connectors but they are unpopulated from the factory.
...Leave a comment:
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Re: VIZIO M50-C1, powers on, no backlight, no picture
Thank you, neilc6. I'm slightly familiar with BGA rework because a friend had a hot air setup for repairing XBOX 360 consoles years ago.
I am currently out of town and away from my tools, so I'm waiting to borrow a DMM from a friend here.
Out of curiosity, I removed the main board and was horrified by the state of the other side. What happened here?!
I had previously noticed what I assumed was thermal compound in strange places on the main board and thought it was from sloppy assembly...Leave a comment:
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VIZIO M50-C1, powers on, no backlight, no picture
Hi All! I've had several successes repairing TVs thanks to the helpful members here. I'm back today with another TV rescued from the curb.
This is a VIZIO M50-C1. Previous owner posted it for free on craigslist with description 'powers on but no picture.' I was unable to get more information from them.
When plugged in, the mainboard LED lights solid purple for 2 seconds, then changes to solid red. As the mainboard LED changes to red, the front LED lights solid white and fades to off over 5 seconds.
When I press power on either the set or the remote,...Last edited by gustagen; 08-09-2020, 01:22 PM. -
Re: Samsung UN55F6350AFXZA, partial backlight failure, scorched components
The replacement backlight strips arrived a couple days ago.
I managed to install them and get the TV reassembled without issue.
I patched the melted area of the backlight reflector with a small piece of thick white paper coated with gloss white spray paint. There’s no sign of the repair, even when displaying a solid light-colored background.
I turned the backlight level down to 12 out of 20.
I’ve logged about 12 hours on it with no problems....Last edited by gustagen; 09-06-2019, 10:17 PM.Leave a comment:
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Re: Samsung UN55F6350AFXZA, partial backlight failure, scorched components
I just ordered a full set of new strips.
I will report back when they arrive and I install them.
While I wait, I’ll stay busy attempting to patch the burn hole in the paper reflector. Any suggestions?
I plan on rotating the reflector and the diffuser panels so that any minor difference in light with be in the lower right corner of the screen rather than the upper left.Leave a comment:
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Re: Samsung UN55F6350AFXZA, partial backlight failure, scorched components
Thanks nomoresonys! The video you linked to shows similar scorching in a different area of the backlight strips. Scary stuff!
I will probably just lower the backlight level as budm suggests, rather than make changes to the hardware as the video shows.
Thank you for the link.Leave a comment:
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Re: Samsung UN55F6350AFXZA, partial backlight failure, scorched components
Thanks budm! I think you've been involved in all of my repairs here so far.
Thanks to you, I already know about turning down the backlight level to prevent future problems.
I will look for a deal on a complete set of new replacement strips.Leave a comment:
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Samsung UN55F6350AFXZA, partial backlight failure, scorched components
Hi again! I've had great success with repairing several LCD monitors and TVs with the help of the friendly members here.
I recently rescued a Samsung UN55F6350AFXZA from the curb.
I powered it up and let it run for about an hour. It seemed to work fine other than half of the backlights not functioning, and a dark splotch near the upper left corner of the screen.
I disassembled it and found some scorched components on one of the backlight strips. There are also components on other strips that appear to have been overheated, with discoloration showing through...Last edited by gustagen; 08-28-2019, 01:39 PM. -
Re: LG 55GA6450-UD LED backlight fails but returns after power cycling
I've had some time to test the TV at higher backlight levels.
It seems to work fine with the backlight set to 35%, and I'm satisfied with the picture.
Thanks again budm!Leave a comment:
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Re: LG 55GA6450-UD LED backlight fails but returns after power cycling
Thanks for the additional info.
I didn't realize the panel was edge lit, and was assuming I'd need several of the single LED strips I was seeing for sale.
How many strips are in the TV? If it needs only one or two, the expense seems more reasonable.
It seems this panel is LC550EUN SF F2. I've attached a photo of the label.
Do edge lit panels require the same type of disassembly as the back lit models, or are the strips replaceable without removing/handling...Leave a comment:
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Re: LG 55GA6450-UD LED backlight fails but returns after power cycling
I was afraid you'd suggest that the LED strips were the problem.
I successfully replaced all of the strips in a 32" LG back in August with your help, and then set the backlight level to 65%. It's still working fine.
This 55" LG has panel LC550EUN and driver PCB 6917L-0118A. It appears that its LED strips are much more expensive and harder to source.Leave a comment:
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Re: LG 55GA6450-UD LED backlight fails but returns after power cycling
I turned the backlight level down to 0 and the TV has been working for 20 minutes now.Leave a comment:
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LG 55GA6450-UD LED backlight fails but returns after power cycling
I am 4 for 4 with TV and monitor repairs with this forum's help.
I recently acquired an LG 55GA6450-UD LED TV with a backlight issue.
It powers up and works normally for 1-5 minutes, then the backlight turns off. Audio continues to work and the picture can be seen with a flashlight.
If power is cycled, the backlight functions again for 1-5 minutes, then turns off. I tested this over 20 times.
The screen looks evenly lit when displaying an all white image.
Thanks for any help you can offer!... -
Re: LG 42LN5400 backlight issue, double-check my troubleshooting
I purchased mine from eBay seller 'luckyelectronic'.
[URL="https://www.ebay.com/itm/Replacement-Backlight-Array-LED-Strip-for-LG-42LN570S-42LN575S-42LA620S-LC420DUE/222996774308"]https://www.ebay.com/itm/Replacement-Backlight-Array-LED-Strip-for-LG-42LN570S-42LN575S-42LA620S-LC420DUE/222996774308[/URL]Re: LG 42LN5400 backlight issue, double-check my troubleshooting
I purchased mine from eBay seller 'luckyelectronic'.
[URL="https://www.ebay.com/itm/ReplaLeave a comment:
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Re: LG 42LN5400 backlight issue, double-check my troubleshooting
I found the lowest price for replacement LED strips on eBay by searching for "LC420DUE" which was on the chassis label indicating the panel model.
I was sure to order NEW strips, not used. My set was about $33, including shipping from/to the USA.Leave a comment:
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Re: LG 42LN5400 backlight issue, double-check my troubleshooting
[B]Success![/B]
The replacement LED strips arrived and the TV is working great.
I turned the backlight level down to 60% to help these emitters last a bit longer. I'll do the firmware update, too.
Thanks, everyone!Re: LG 42LN5400 backlight issue, double-check my troubleshooting
[B]Success![/B]
The replacement LED strips arrived and the TV is working great.
I turned the backlight level down to 60% to help these emitters last a...Leave a comment:
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Re: LG 42LN5400 backlight issue, double-check my troubleshooting
That's good advice, budm. Saving a few dollars now might result in a cracked panel later!
In addition to lowering the backlight level, I've read that a firmware update is also advised when replacing these backlight strips. Apparently the new firmware doesn't drive the emitters quite so hard.
I'll order the parts today and report back when they arrive. Thanks again!Leave a comment:
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