FAQ
TL;DR: LG 42LB650V black screen/no backlight? After repair, avoid "100%" — "reduce the level of backlight" to extend LED life. [Elektroda, itadek, post #17162430]
Why it matters: It helps LG 42LB650V owners and repairers focus on failed LED strips, avoiding needless PSU swaps.
Quick Facts
- Flashlight test: image visible on-screen confirms the LCD works while the backlight is off. [Elektroda, kar-bau-kopec, post #17162278]
- LED output observed at about 60 V on power-up, then drops to 0 V during fault. [Elektroda, kar-bau-kopec, post #17162388]
- Likely root cause here: “burnt LED on the backlight bars,” not the PSU. [Elektroda, Pedros050, post #17162405]
- After repair, lower backlight; prior setting was 100% power to avoid repeat failures. [Elektroda, itadek, post #17162430]
- Access to strips requires stripping the matrix; see photo of bars after disassembly. [Elektroda, Pedros050, post #17162446]
How do I confirm the backlight is dead on an LG 42LB650V?
Shine a flashlight at an angle onto the screen while powering on. If you see the image, the LCD works and only the backlight is off. This simple test separates backlight faults from other failures. [Elektroda, kar-bau-kopec, post #17162278]
What does a brief ~60 V that drops to 0 V on the LED connector mean?
It shows the LED driver attempts startup, then cuts output. In this case, voltage reached about 60 V and fell to 0 V. That pattern points to a backlight strip fault rather than a stable power supply output. [Elektroda, kar-bau-kopec, post #17162388]
Is the power supply board EAX65423701 the cause of no backlight?
Often not. A member diagnosed a “burnt LED on the backlight bars,” which prevents backlight even with a good PSU. Replacing the power board alone will not restore light if the strips are open or shorted. “Burnt LED on the backlight bars.” [Elektroda, Pedros050, post #17162405]
Where do I find the panel (matrix) model label in this LG?
Look for a sticker on the metal matrix housing. That label carries the panel designation used for service references. Inspect it before ordering LED strips or parts. [Elektroda, Pedros050, post #17162348]
What power supply board does the LG 42LB650V use?
It uses the EAX65423701 (2.0) power supply board. Note this when comparing or sourcing replacements. [Elektroda, kar-bau-kopec, post #17162332]
What’s the exact TV model discussed here?
LG 42LB650V. Use this when searching for backlight strips, PSU, and panel documents. [Elektroda, Pedros050, post #17162372]
Should I attempt to replace the LED strips myself?
It is delicate work that requires full panel disassembly. A member advised handing the TV to an RTV service point. This approach avoids damage when accessing the lighting strips under the matrix. [Elektroda, Pedros050, post #17162405]
How much does replacing LED backlight strips cost?
There is no fixed price. As one technician noted, “each website counts differently,” so ask local service centers for quotes. Expect variability by region and parts used. [Elektroda, Pedros050, post #17162446]
What do the LED strips look like and where are they?
They are linear bars under the LCD matrix. A photo in the thread shows the strips after removing the panel layers. Access requires careful disassembly on a flat surface. [Elektroda, Pedros050, post #17162446]
What settings should I change after backlight repair?
Lower the backlight level in the Picture menu. A member reported previous settings at 100% power, and advised reducing it to improve longevity. This reduces thermal stress on new strips. [Elektroda, itadek, post #17162430]
I replaced the power supply board and still have no backlight—why?
A used, “seemingly functional” power board did not restore LED voltage in the reported case. That points to failed LED strips instead of a PSU fault. Diagnose strips before buying more boards. [Elektroda, kar-bau-kopec, post #17162278]
Will I always see backlight voltage when the TV powers on?
No. In the case discussed, the LED output showed about 60 V at startup, then dropped to 0 V. That behavior indicates a fault and prevents steady illumination. Measure at power-on to catch this brief event. [Elektroda, kar-bau-kopec, post #17162388]
Is there a step-by-step to check this backlight issue?
Try this quick flow:
- Do the flashlight test to confirm the image appears.
- Measure LED connector voltage right at power-on.
- If voltage is missing or collapses, suspect failed LED strips and plan replacement.
[Elektroda, kar-bau-kopec, post #17162278]
Is there a repair video for the same model?
Yes. A forum member linked a repair video for this exact TV model and warned to avoid common mistakes. Watch before attempting disassembly. [Elektroda, E8600, post #17162734]
