Vizio E500i-A0 backlight on 1/2 second off 2 seconds

[j0etee1]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

Thanks.. your advice is sound in my humble opinion. That is what I will do. First try a new PSU and resell it if it does not resolve the issue; then disassemble the unit carefully and if sucessful buy new LED strings.

[vinceroger69]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

maybe budm will have a quick look at your led voltages when he sees this thread be nice too see what his thoughts are on this fault and what advice he offers on what to do next im still learning myself hence trying a psu first as i would hate too damage a lcd of that size.

[dick_barton]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

What is the part number on the chip shown in the red box?

Photo courtesy of Shopjimmy

[dskall]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

I believe the voltage drop on these are about 3.2v.

[budm]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

LC500DUG-(JF)(R1)
Per spec sheet, it has 30 LEDs per string, one string contains 3 arrays, each array has 10 LEDs.
You have two stings, the strange part is that the Forward Voltagae is rated at 111V Typ.
We need to know what you have on the bl-on and the dim control signal.

[vinceroger69]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

LC500DUG-(JF)(R1)
Per spec sheet, it has 30 LEDs per string, one string contains 3 arrays, each array has 10 LEDs.
You have two stings, the strange part is that the Forward Voltagae is rated at 111V Typ.
We need to know what you have on the bl-on and the dim control signal.

I dont know why i didnt think about asking if you have these two voltages from the mainboard thats one of the important tests too do.

as budm says the voltage your led tester is showing seems low at 95v where it works out at 111v not sure why that is.

[dick_barton]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

At 111V typical would equal 3.7V per led (30 x3.7V). So would 95.6 volts be indicative of 4 shorted leds per string? Shorted because they still light up.

[vinceroger69]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

At 111V typical would equal 3.7V per led (30 x3.7V). So would 95.6 volts be indicative of 4 shorted leds per string? Shorted because they still light up.

yes having 8 leds faulty is quite common i guess if the voltage tests are correct on the mainboard voltages maybe it does require a panel stripdown.

[j0etee1]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

What is the part number on the chip shown in the red box?

Photo courtesy of Shopjimmy

very difficult to see... appears to be SEM5 28 with 179 below it????

[j0etee1]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

LC500DUG-(JF)(R1)
Per spec sheet, it has 30 LEDs per string, one string contains 3 arrays, each array has 10 LEDs.
You have two stings, the strange part is that the Forward Voltagae is rated at 111V Typ.
We need to know what you have on the bl-on and the dim control signal.

I do not know how or where to get these measurements. By that I mean:
Do I need to have the entire system connected and powered up?
Where do I get the Dim control signal? Do I need to use my ocilliscope?
Where do I get the BL-on control signal?

As for the forward voltage of the LEDs strings I see your point of concern. Possibly, I do have the exact amount of LEDs out on each string which would indicate that the 95.5vdc tested on each string rather than 111vdc minimum to turm them on.

[budm]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

The problem with using the LED tester is that we do not know what the forcing current is set to, the Vf of the LED will vary with the Forward current being applied to the LED.
As you can see from the graph for the 200mA LED, you will see the affect of the current has on the Vf of the LED.
The LED used in this TV per spec sheet is 400mA, as you know, it is really pushing it, that will be more than 1W.
So the tester is probably not putting out 400mA so the readout does not come out as around 111V per spec. OP should put DCA meter in series with the output of the tester to see how much current is be forced through the LEDs.

[vinceroger69]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

I do not know how or where to get these measurements. By that I mean:
Do I need to have the entire system connected and powered up?
Where do I get the Dim control signal? Do I need to use my ocilliscope?
Where do I get the BL-on control signal?

As for the forward voltage of the LEDs strings I see your point of concern. Possibly, I do have the exact amount of LEDs out on each string which would indicate that the 95.5vdc tested on each string rather than 111vdc minimum to turm them on.

is there any writing by the power supply connectors? it should say bl on dim control etc by one of the connectors going too the mainboard

[dick_barton]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

One red box shows the legend for the connector in the 2nd red box but unfortunately your picture is out of focus to be able to read them. There's also a another yellow box giving voltages and again cannot read it.
Perhaps you could post clear pictures of those two areas.

[desho1]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

Vizio E500i-A0 backlight on 1/2 second off 2 seconds have picture w/ flashlight and sound.

[skyjacker03]

Re: Vizio E500i-A0 backlight on 1/2 second off 2 seconds

I have a similar problem. LED1+ and LED2+ I have 87V with Power on and the connector connected, same if I unplug the connector with power on.
If I turn the power off with the connector disconnected I have 14V that trickled down to 0V. Any ideas? I watched a youtube video but couldn't tell if I should have had the TV plugged in or not plugged in when testing with the connector unhooked.