Vitron 55" QLED - No Backlight, LED Driver Failure (September 2025)

Customer calls: "TV has sound but no picture. Well, there's a picture if I shine a flashlight at it."

That's a backlight failure. On this Vitron 55" QLED, it wasn't the LED strips - it was the driver circuit.

Understanding the Symptoms

Classic backlight failure. TV turns on, you can hear sound, and if you look really closely or shine a light at the screen, you can see a faint image.

The panel works. The main board works. But the backlight doesn't.

Opening It Up

The Vitron 55" QLED uses a standard board layout. Power supply on one side, main board in the middle, LED driver integrated into the power supply section.

Checked the 12V input to the LED driver. Present and stable. Good.

Checked the output to the LED strips. Zero volts. Not good.

So the driver circuit was getting power but not outputting anything.

Locating the Failure

LED driver circuits use a boost converter topology. There's a controller IC, a MOSFET for switching, an inductor, a diode, and feedback components.

Started checking components. The controller IC was getting power. The MOSFET was fine. The inductor was fine. The diode was fine.

Then I checked the feedback circuit. These drivers use a voltage divider and optocoupler to regulate the output voltage. If the feedback is wrong, the driver won't start or will output the wrong voltage.

Found it. One of the capacitors in the feedback circuit was shorted. Reading 0.3 ohms to ground.

This capacitor filters the feedback signal. When it shorted, it pulled the feedback voltage to ground. The controller saw this as "output voltage is zero" and shut down to protect itself.

The Fix

Replaced the shorted capacitor. It's a 100µF 25V electrolytic, super common part.

Also replaced two other capacitors in the same circuit that were reading high ESR. If one failed, the others are probably not far behind.

Powered it up. The backlight came on immediately. Bright, even illumination across the entire QLED panel.

Why This Happens

Cheap capacitors in hot environments. The LED driver section gets hot because it's handling significant power. If you use 85°C rated capacitors in a hot environment, they degrade.

The solution is to use 105°C rated capacitors. They cost maybe 20 cents more. But manufacturers won't do it.

I've repaired dozens of Vitron QLED TVs with this exact failure. Different models, same problem. Because they all use the same cheap components.

Testing Results

Let the TV run for three hours to make sure it was stable. Checked the LED driver output voltage: 96V, rock solid.

Checked the backlight uniformity: perfect, no dark spots or bright spots.

Customer picked it up, happy as can be. Total cost: $70. New QLED TV would have been $600.

The Bigger Picture

This repair took 45 minutes. One shorted capacitor was killing the entire backlight system.

But most people would just buy a new TV. They don't know this is repairable. And the manufacturers certainly aren't going to tell them.

This is why right to repair matters. This is why component-level repair matters.

A 55-inch QLED TV with a $0.50 failed component shouldn't become e-waste.