Vizio E470VL backlight circuit sensitivity

[pongagt]

Re: Vizio E470VL backlight circuit sensitivity

10 tubes - damn that's gotta generate some heat!

There are 20 tubes and my VO420E has 18 tubes.

[stj]

Re: Vizio E470VL backlight circuit sensitivity

10 tubes - damn that's gotta generate some heat!

[budm]

Re: Vizio E470VL backlight circuit sensitivity

So when you turn it on right now, you do see ALL the lamps light up, right?
BTW, which version of this model do you have? The one with power supply-inverter combo board? Or the one with separate power supply, inverter board.
LCD panel model number?

[Taterbug]

Re: Vizio E470VL backlight circuit sensitivity

Here is a photo of the backlights...

[stj]

Re: Vizio E470VL backlight circuit sensitivity

how many tubes does it use?
is it edge-lit or back-lit?

[Taterbug]

Re: Vizio E470VL backlight circuit sensitivity

The bulbs look white and it has a beautiful picture when I can get it to play. I tore it back down and double checked for more arc spots and did not see any. If the cables that I've got coming don't fix it then I will just hold on too it until I can find one with a cracked screen. Thanks.

[budm]

Re: Vizio E470VL backlight circuit sensitivity

"I ohmed out the lamps to gound using a VOM on megohm range and could find no shorts to ground" The meter cannot put out 2000V to simulate the high voltage than can cause high voltage break down.
I agree that you may have bad lamps, or still arcing some where.

[stj]

Re: Vizio E470VL backlight circuit sensitivity

what do the tubes look like?

if they are ice-white with silver ends they are new,
if they are white with darkened ends they are old,
if they look a bit yellow and the coating looks powdery instead of smooth they are done.

[Caleb]

Re: Vizio E470VL backlight circuit sensitivity

Is the inverter on the power supply? Can we see some pictures? It sounds like you may have one or more cfls that are taking more amperage than the inverter likes then it shuts them off. Shopjimmy shows about 4 different power boards used in this model. Which does your tv have? If it will turn on with the screen removed you can check for dim bulbs, or ones with black stripes around the end.

Sometimes it is just better to move on for a bit and come back to it later. Ive got a Samsung that wont keep the backlights on for more than a few seconds, waiting for another cracked screen to come in with compatible bulbs as I cant get enough matching tubes to make the balancer happy.

[Taterbug]

I have been working on an Vizio E470VL for months and it is driving me crazy that I can't fix it. I plays for just a few minutes (5 at the most) then the back light shuts down. Every time I loose the lamp voltage going to the PS board. I have replace the power supply board and also have replaced the main board THREE times and still having the same problem. Last night I went as far as to tear the whole thing down and remove the LCD screen and examined the Backlight lamps and associated wiring looking for arc spots. I did find one small spot next to the connector on the circuit board that holds the lamps. I cleaned that spot and insulated it thinking it would cure the problem. The spot was very very small about the size of a pin head. I reassembled everything and still have the problem. I found a new set of cables on e-bay that I ordered. This is about the only thing left that has not been replaced. I ohmed out the lamps to gound using a VOM on megohm range and could find no shorts to ground. Is their anyway to make the Lamp feedback circuit less sensitive? Or do you think it could possible be a bad cable? I should get the cables in a couple of days and that will eliminate that problem. I have also just installed a new eprom on the new main board I received just to double eliminate that problem. Anyone else had this problem???