Element ELCHW402 pulsing backlight?

[boshuter]

Element ELCHW402 Power supply board 125372

I have this tv that was brought to me by a friend. I was told that lightning had hit the satellite dish and took out the satellite receiver and tv. A visual inspection didn't show anything that looked bad, but the tv would power on for about 30sec and then pop and turn off. I found that one of the large chips on the main board was getting very hot. Since I had access to another main board, I swapped it out and the tv started right up and stayed on. But... there is a "pulsing" in the backlighting, this is a regular pulse not a flickering. It is definitely in the backlight, it starts as soon as the backlight comes on and continues even with cable to tcon board removed. It is a subtle pulsing and not even noticeable when there is a multi colored or moving picture on screen. It is easily seen when on a one color screen such as you get with no input hooked to the tv. I also replaced the inverter board with a known good unit with no change. It seems like it has to be a power board problem, but I'm not sure where to start or what could cause this problem

I checked the voltages on the power board going to the inverter and there is a definite pulsing on the 24v pins, if you remove the inverter cable, the voltage is rock steady. This voltage pulsing is in sync with the backlight pulsing.

If anyone has seen this, or can help solve this problem, please let me know.

[capkid]

Re: Element ELCHW402 pulsing backlight?

It sounds to me like an inverter issue. I wonder if you have a bad transformer.

[boshuter]

Re: Element ELCHW402 pulsing backlight?

It sounds to me like an inverter issue. I wonder if you have a bad transformer.

That's what I thought, but I swapped in an inverter out of a working tv and nothing changed. The backlights stay on and the tv will work fine for hours other than that slight pulsing.

Also, the pulsing is the entire backlight, it's even from top to bottom of the screen.