Haier Curved 4K 55ufc2500 No backlight

[rikrikrik13]

I have 2 haier 55UFC2500.

Both will turn on without backlight.

I tested at the powersupply LED strip connector (There's 2 connector).

I get 240V at one connector and 0 at the other.

240V seems way too high ? I think there's a short on one side and the powersupply is pushing the whole 2 sides voltage on one side…

If it the case, all the leds are burned now?
here's some pictures

[budm]

Re: Haier Curved 4K 55ufc2500 No backlight

We need straight shot pictures of the whole top and bottom side of that power supply board.
It does sound like you have open circuit (bad LED, connector, wiring, etc.) in the LED strings some where.
What is the LCD panel number?

[rikrikrik13]

Re: Haier Curved 4K 55ufc2500 No backlight

Thanks, I can't find the panel number.

I checked again with the multimeter on the chassis and Led+

Turn tv on : 350V
After : 320V

I got 0V at the other led+ connector

I checked the voltage that goes to the main board on the powersupply and it's all good.

[budm]

Re: Haier Curved 4K 55ufc2500 No backlight

Without seeing the bottom side of the board, it looks like the LED strings are connected in series, so based on your Voltage readings it indicates open circuit in the LED string.

[rikrikrik13]

Re: Haier Curved 4K 55ufc2500 No backlight

you were right.

I have 2 tv's, one with a broken screen but both with the same problem (backlight won't turn on).

I removed everything from the one with the broken screen, there's 10 lights strip with 5 led on each.

I tested each strip with a 12v powersupply (I know it's not enough to turn them at full brightness but enough to turn them at super low intensity).

on 10, one light strip didn't turned on (open)

Now, I need to disassemble the other TV without breaking anything to replace maybe one bad led strip or more (I don't mind, I have 9 good strips lol). wish me good luck lol

[Andrew F. Ali]

Re: Haier Curved 4K 55ufc2500 No backlight

Curved screens are VERY tricky to handle. They break very easy. You will need vacuum suction cups to pick it up. The question is where would you put it down without it breaking?

[floodster1]

Re: Haier Curved 4K 55ufc2500 No backlight

Hi did you find the fix for your problem, i all so have a Haier 55ufc2500 but in my case im looking for back lightled strips, i seem to find them on line.
Could anyone help me with this problem?

[neilc6]

Re: Haier Curved 4K 55ufc2500 No backlight

I just got one of these in and have repaired about 3 previously. Symptom is TV turns on and off without backlight. It takes about 10s for the TV to turn on. Only found two suppliers for new strips (CRH-K55EMD30301005684). They are configured 10 rows of 5 LEDs mounted vertically in two strings. Both sources are pretty expensive so I just replaced the LED module (3V Samsung style, typically 1 or 2 bad). Keep it in energy savings mode which sets the backlight at 50%. Standard and Vivid modes run the backlight at 100%. You can only set the backlight manually in the service menu under panel settings (menu-1-1-4-7).

In this model, it is a flat screen fit in a curved chassis.

[voltythecat]

Re: Haier Curved 4K 55ufc2500 No backlight

Hi, folks. Brand new here - very experienced EE but total n00b when it comes to messing with newfangled TVs.

I was recently given one of these, and the screen's black. It appears to power on, but that's about as far as I can go - it's a chicken-and-egg problem. Without the onscreen menus I can't select an input and try to determine to what extent it's working. If I could do *that* much I could at least get proof of life from the audio.

If the general assumption is that it's a bad LED thing, where do I start looking? And how much is it worth spending to revive it?

[neilc6]

Re: Haier Curved 4K 55ufc2500 No backlight

Backlights burning out is the most common failure in LED TVs since LEDs will burn out just like light bulbs. Typical symptom is that the TV will turn on with no backlight or flash of backlight. Just checked the part number on Aliexpress and lots of vendors now for new replacement strips and reasonable pricing. It is a 55" 4K TV but very easy to damage the panel in the repair process and even trickier with a curved chassis. With a LED tester and if there is no open circuit in the string, you can power up the backlight independent of the power supply to check the panel before investing in new strips.

https://techhometravel.com/lg-ln-ser...ed-backlights/

[voltythecat]

Re: Haier Curved 4K 55ufc2500 No backlight

Okay, so the LED replacement is a reasonable/obvious approach.

Do I understand correctly that the LED supply is via those two little connectors, each with the red/black pair, that's on the upper right hand corner of the switcher, nearest buddy's DVM in the photos?

If so, what can I see on those pins that will confirm good supply and bad lights? If not, where do I look? And what on earth is a "LED tester", in this context?

And can you recommend a source for replacement LEDs? I really want to keep the cost down on this, and normally having US purchases routed to a PO box just south of the border works, but the last couple of years have been a real challenge getting over there to pick up the mail. You're in BC - you get it.

[neilc6]

Re: Haier Curved 4K 55ufc2500 No backlight

Yes the two red black pairs indicates the LEDs are wired in two separate strings. If you measure the voltage on one side, you may observe the voltage spike up before shutting down. A LED tester is a constant current source for testing LEDs. It will read the voltage drop across the DUT. Search the strip part number on Aliexpress. Typically 2 to 4 weeks for shipping if you use Aliexpress Standard Shipping.

[voltythecat]

Re: Haier Curved 4K 55ufc2500 No backlight

Ah, I see - and they're real econo, as in I can land one for $20. The Chinese make junk, but at least they make cheap junk!

So I'm looking at a supply of a couple of hundred volts or something. How fast does it drop after power-up? Fast enough that I should be using an analog meter rather than the DVM? Or do I have a few seconds until it detects the no-load condition and shuts off?

[neilc6]

Re: Haier Curved 4K 55ufc2500 No backlight

All the strips are made in China. If you buy from a US seller, they just import and resell them. The power supply may have a silkscreen with the output voltages. With 50 leds in 2 strings and approx 3V per led, you are looking at 75V per output but they could be wired in series so 150V. I don't do the voltage spike test since I have a LED tester. With TVs that have a flash of backlights or logo, I don't even test and just order new strips. With no flash, I test to confirm an open circuit in the string or power with my LED tester if there is more than one string to check the panel before ordering new strips.