FAQ
TL;DR: LG 55LB650V flashing is usually a backlight issue; one confirmed fix replaced 2 LEDs (6V/2W). "Disassembly at this size is an extreme sport." Follow the steps below. [Elektroda, ganitu, post #17125222]
Why it matters: This FAQ helps DIYers and technicians diagnose a flashing 55LB650V fast, prioritize the right parts, and avoid panel damage.
Quick Facts
- Blink rate reported: about 2 flashes per second right after power-on. [Elektroda, seralion, post #17020724]
- Common root cause: failed LED backlight — "Damaged LEDs, standard." [Elektroda, shrederr, post #17520062]
- Symptom pattern: picture/menus still respond while only the backlight cycles. [Elektroda, seralion, post #17021511]
- Backlight assembly detail: 10 LED slats; replacement kits include double‑sided tapes. [Elektroda, kusalek, post #18654802]
- Observed LED‑driver outputs: start near ~178V/~118V, then stabilize around ~157V/~104V. [Elektroda, kusalek, post #18654802]
Why is my LG 55LB650V screen flashing every half-second?
That flash indicates the LED backlight protection cycling due to a fault. Members identify it as “a typical symptom of backlighting.” The LED strings open under load, the driver retries, and you see a repeating blink. Plan to inspect or replace the affected LEDs or strips. [Elektroda, tomek5333, post #17021857]
How can I tell if it’s the backlight and not the mainboard or T‑Con?
If menus and video still react while brightness pulses, the panel and mainboard are alive. That pattern points at the backlight subsystem. A user reported normal image behavior with only the backlight flashing. Check backlight connectors and strips instead of signal boards. [Elektroda, seralion, post #17021511]
Can power‑supply capacitors cause this flashing?
Yes, a short or overload on the LED output, or failing output capacitors, can cause cycling. One member flagged the supply and its output caps as suspects. Measure LED‑driver rails under load and verify capacitor ESR, not just appearance. If ripple is heavy, service the supply side. [Elektroda, elcomandante, post #17020893]
What’s the better fix: replace all strips or only the bad LEDs?
If you have hot‑air tools and skills, replace only failed diodes on the strip. If you lack hot air, replace entire strips for reliability. Full strip replacement reduces repeat openings on large panels. Keep thermal balance consistent across the set. [Elektroda, tomek5333, post #17120013]
How do I replace the backlight safely?
Do this methodically to avoid panel damage.
- Remove the panel and diffusers to expose strips; note strip order and wiring.
- Test each LED/strip; with hot air, lift and replace faulty diodes, or swap strips.
- Reassemble carefully, ensuring all connectors are seated and no dust remains.
“With hot air you can change the diodes themselves.” [Elektroda, tomek5333, post #17021857]
How many strips are in the 55LB650V and what voltages should I expect?
Expect 10 backlight slats in this chassis. One repair logged initial readings near 178V and 118V on two strings. They stabilized around 157V and 104V after start. Use these as sanity checks during diagnosis. [Elektroda, kusalek, post #18654802]
What tools do I need for this job?
A hot‑air rework station is the key tool for swapping individual LEDs. If you do not have hot air, plan on replacing whole strips instead. Prepare a clean, organized workspace and protect the panel throughout. Label connectors during disassembly. [Elektroda, tomek5333, post #17120013]
How do I remove LED strips that are glued tightly to the chassis?
The strips adhere very firmly to the metal sheet, so work slowly and evenly. Expect strong resistance from the adhesive, especially near the ends. Avoid twisting; lift along the length to prevent bending. Plan extra time for removal. [Elektroda, kusalek, post #18642435]
I replaced all 10 strips and it still flashes — what next?
Verify both LED‑driver outputs start high and then stabilize, as documented by another repair. Reseat backlight connectors and check for pinched cables. Confirm the replacement strips match original type and wiring. Flashing can persist until rails settle under load. [Elektroda, kusalek, post #18654802]
Is backlight failure common on this LG model?
Yes. Experienced members describe it as typical for this chassis. “Damaged LEDs, standard.” Prioritize checking the backlight before suspecting logic boards. [Elektroda, shrederr, post #17520062]
Can I trust visual capacitor checks to rule out PSU issues?
No. A good‑looking electrolytic can still be bad. “Visual check is far too little”; measure capacitance or ESR with a meter. Test in‑circuit only if supported by your instrument, or lift a lead for accuracy. [Elektroda, niewolno2, post #17021931]
What LED rating does this set use on the strips?
One confirmed case used 6V, 2W LEDs on the backlight strips. Two such LEDs failed and replacement restored operation. Use matching ratings when swapping devices or entire strips. [Elektroda, ganitu, post #17125222]
My set blinks about 2 times per second — what does that indicate?
That rate matches a documented case right after power‑on. It aligns with the LED driver retrying due to a backlight fault. Start with backlight strip and LED checks. [Elektroda, seralion, post #17020724]
