Element ELEFT502 No Picture - Blue Power Light Comes On

[barryra]

Someone broght me this Element TV where the blue light comes on down at the bottom right but there's no picture or sound. They said they bought this last year on the Black Friday sale. Caps look good. thanks for any help.

[Pentium4]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

Post clear pictures of all the boards, top view and solder side if possible

[Tsugigas]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

Hello,

Not to hijack, nor necro. I can post pictures of my boards for the same model TV. If your willing to give advice, it would be much appreciated. I can post them tomorrow.

Regards,
Tsu

[nomoresonys]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

check anything labeled F for fuse, careful working with power supply boards HIGH VOLTAGE on primary side.

[johnboy1313]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

I recently picked one of these up with the same fault. I found a blown LED on one of the LED strips. I replaced the strip with one from an ELEFW502 and it powered on fine. Unfortunately, the screen was either damaged before or during the teardown. I wound up parting it out on eBay. I still have the boards and most of the strips from the ELEFW502 if you need any parts.

If you look closely, it's the sixth LED from the left in the top row. It was complete blown open and burnt.

[suceava20]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

I have the same problem , same model , with blue light on.

So the LED strip , one of them maybe bad? Did not open yet to fix and not sure if worth fixing.

Thanks

[anthonystv]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

Do you have the power board? I suspected it was a bad LED but my power board doesnt show any DC across the Diode DL2 which I suspect i do show 120V dc across all the diode banks but i dont think its running i suspect i should see around 320V dc there is an osc IC on the power board that drives the transformer to feed DL2 I suspect this is the issue here .... the board i have makes no attempt to fire leds ever
although the main board is sending a BL on ...i may or may not have blown leds in the panal but i wont know until i can get the power board to kick so HV ...i tried to light an individual string with a 24V dc power supply and that does not work either ...acts like they are all open no current draw

[Agent24]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

Where is Diode DL2? Where is this 120V you measured? Post photos and more information.

[budm]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

"i tried to light an individual string with a 24V dc power supply and that does not work either" 24V is not going give enough Vf to turn on the LED, each strip has 14 LEDs so it will take at least 3.3V x 14 = 46.2V + Vr drop for the current limiting resistor.

Where is Diode DL2? Where is this 120V you measured? Post photos and more information.

I like to see that too.

[anthonystv]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

just go to shop jimmy grab a pix of the board MIP550D
DL2 looks like a transistor
it right in front of the LED plugs
I suspect the 120Vdc from the power supply goes through some sort of chopper so you are saying 46.6 X 5 at least 230V dc is whats needed here
so I suspect getting the 120VDC is what the base feed of the chopper is when it apears at the leds its not "chopping"
There is no schematic on this board so Im trying to piece together what should be happening here
The chopper transformer doesnt seem to have a primary and secondary just 3 pins they all are tied together sharing the same primary so if the transformer does not chop you will still get primary voltage out
I think i can safely say I have a bad board here just from the ref you gave about the voltage needed I dont have it !! I suspect its the little SMD driver IC no oscillation no output ...

[Agent24]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

I think I found DL2 but the function is not obvious, besides this only shows the top side so where anything is connected is unknown... plus there seem to be various versions of this board...

Can you post photos of the top and bottom of your board showing the LED driver section?

[budm]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

Can you upload the pictures of the whole back side of the TV so we can see how all the boards are connected together and also how the wires from the LED strips are connetced to the board?

[budm]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

OK, looking at the bottom side of the board, the DL2 is the rectifier at the output of the Voltage booster circuit, the Anode of the first LED string (CON11) is connected to the Cathode of DL2, the 3-pin device on the same heat sink is the MOSFET for the boost converter circuit using Inductor L1A and IC UL1 (you should get the P/N as printed on top of the IC to get the spec sheet and the app notes).
The LEDs string are connected in series.
The cap ECL3A (brown polyester cap is probably rated at 400V or so) is the filter cap for the Boosted output.
You should check the DC Voltage right at the two legs of the cap to see what you get when you turn on the TV.
There is no need for the Open LED detector since ALL the LEDs are connected in series as one string, but the there is over current protection.
http://assets.shopjimmy.com/media/ca...5tb-bottom.jpg

[anthonystv]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

Exactly what I was thinking here ....I cant read the SMD the numbers are gone!
ill check the cap I have seen them open but usually indicated by a bulge or burn mark
i think im just going to have to get the board my board is the board you see above

[Dan Klang]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

do you still have???

[budm]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

do you still have???

You should start a new thread since there is no follow-up to let us know what is going on.

[cspivey]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

I recently picked one of these up with the same fault. I found a blown LED on one of the LED strips. I replaced the strip with one from an ELEFW502 and it powered on fine. Unfortunately, the screen was either damaged before or during the teardown. I wound up parting it out on eBay. I still have the boards and most of the strips from the ELEFW502 if you need any parts.

If you look closely, it's the sixth LED from the left in the top row. It was complete blown open and burnt.

My problem is how do you get the six strips off from the chassis to get to the LED strips?

[cspivey]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

I recently picked one of these up with the same fault. I found a blown LED on one of the LED strips. I replaced the strip with one from an ELEFW502 and it powered on fine. Unfortunately, the screen was either damaged before or during the teardown. I wound up parting it out on eBay. I still have the boards and most of the strips from the ELEFW502 if you need any parts.

If you look closely, it's the sixth LED from the left in the top row. It was complete blown open and burnt.

How did you take the green small boards off from the chassis I'm trying to get to the lights but the bottom part I can't get the strips loose the looked tucked under.

[cspivey]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

[QUOTE=cspivey;610773]How did you take the green small boards off from the chassis I'm trying to get to the lights but the bottom part I can't get the strips loose the looked tucked under.[

[Agent24]

Re: Element ELEFT502 No Picture - Blue Power Light Comes On

Those strips connect the TCON and the LCD row\column drivers and LCD itself. You need to disassemble the panel to get at the backlights.

I hope you have not been trying to pull those flex cables out from inside the panel with any force or you will very likely have trashed the display.