element eldft551 not turning on

[cashkennedy]

I picked up this 55" element eldft551 where the symptoms are that you can turn it on and the power light goes blue, but other then that nothing happens.

There were some hidden screws under the "label" that marks the ports (I think they changed the port layout after the plastics were produced), the previous owner had destroyed the back plastics cause he didn't realize there were screws there when he took it apart to try to fix it.

I tested the power supply and there aren't your usuall "logical" markings so im not sure what pins it uses to know when to turn on. I did notice though that 5vsb is always 5volts and always there. Also when you first plug it in the 12v and 5v both come on, the 12v is a bit low (11.82 volts, this power supply has a bunch of crap capacitors from JH "" but unless there is a voltage monitoring ability that shouldn't be causing it to turn off the voltages) and after you press the power button the 12v and 5v voltages come on for around 1-2 seconds and then turn off , but the tv stay "on" with the blue led lit, and can not be turned off without unplugging. There is also a "stb" wire that goes to 4v when the set is on.

The connector that runs to the main board (im quite certain its the only one that could be turning on the power supply unless morons are routing it through the inverter these days) is marked as
GND
GND
5V
5V
STB < Stays at 4v when the led is on
5VSB <always is 5v
5V
5V <comes on for a few seconds when plugged in and after pressing power button
GND
GND
GND
12V <comes on for a few seconds when plugged in and after pressing power button
12V

I tried jumping the 5vsb to "stb" with a 220 ohm resistor but that didn't make the power supply turn on (because I didn't see the blue light come on) , but perhaps that isn't the right logic so to speak and ill go see if the 12v and 5v come on for a second when I have the jumper in place.

Sorry for horrible pictures, I haven't figured out the best settings to use on my new cell phone for indoor shots.

Im gonna go look at elektrotanya for a service manual.

[budm]

Re: element eldft551 not turning on

The Blue power LED runs off 5V STBY. The STB pin is more likely the same as PS_ON pin that gets the signal form the main board to turn on the switched 12V, switched 5V, and 24V? (pictures are too dark for me to see in details. I will wait for better pictures first.

[cashkennedy]

Re: element eldft551 not turning on

I checked, but found no service manual on ET

I was about to check for the voltages coming on with the jumper in place, but ill need to rig up a way to easily connect or disconnect the jumper / otherwise I notice no change plugging it in with or without the jumper since the 5v and 12v come on for a second either way when first plugged in.

Attached are some better pics, but tell me of course what youd like / if you want the backside of the power supply so on... seems my phone prefers no flash / and have to tap the part of the screen you want it to focus on

The caps are all JH except for the large dc cap which is jianghai, so I assume all the JH stand for jianghai... the mainboard is all KLA... I think its great that Chinese companies can spring up over night have have a whole spread of different capacitor products, I mean if I was starting a factory I think I would focus on 1 series and perfect it, but these people somehow manage to overnight be turning out a thousand products...

[johnboy1313]

Re: element eldft551 not turning on

You have to realize that if you or I were to start a business, we'd have our children and grandchildren's livlihood at intersest. These Chinese factories aren't necessarily interested in the future. They want to pump out as much product as they can before any regulations start to pop up.

[johnboy1313]

Re: element eldft551 not turning on

And I'm suspecting mainboard here. It looks like your PSU is working but going into protection.

[tom66]

Re: element eldft551 not turning on

It takes next to nothing to design and make capacitors based on stolen or incorrect capacitor formulas in China. That's why we treat most Chinese capacitors as suspicious. Whereas Japanese manufacturers, and companies like Samxon, have invested a fair bit of money into the development of proper construction techniques and chemical formulae to make reliable, long lasting capacitors.

[budm]

Re: element eldft551 not turning on

OK, you do have PS_ON (STB) signal of 4V, you can verify that again when the TV is off and when the power switch is activated. You should also see the 24V at those bundle of the red and black wires.
Since this board has PFC Voltage booster, you need to monitor the voltage RIGHT AT THE TWO LEGS of that large 450VDC filter cap, it should go up from 160VDC (IN STANDBY), and the stay at aorund 380VDC when power switch is activated.
One thing is not right is that you cannot turn off the TV with power switch, that will indicate the main board is not function properly either.
You can also try disconnecting the 24V connectors that goes to the inverter boards to see if the 12v/5v/24V (they are generated by the same transformer) will stay on.

[cashkennedy]

Re: element eldft551 not turning on

I had already tested it with the inverter plugs disconected , and it didnt affect the other voltages. the 24v rail also comes on for a short period similar to how the 12v and 5v rails come on.

I tested the large caps voltage and i get around 160-180 in standby and 380 the first few seconds when i plug it in. And finally i get 380 -400 when i turn the power on to the set, and it stays that way at 380v till i unplug the set to turn it off, even though the 5v,12v and 24v all fade away after a 2 seconds of the set being "on".

My comment on the ability to make a full line of capacitors was more along the lines of : they might actually seem like they were trying to make quality caps if they just focused on 1 type of cap / but instead its obvious they ship total crap if they can make every single size and type right from day one.

And wow this is my first set larger then 42" and it is destroying my back, how do you work on a 84" sets ? do i need a harnass and a track over my work bench so i can hoist myself over the middle of the set for an 84"?

[johnboy1313]

Re: element eldft551 not turning on

I would have no way to work on an 84" set. My bench is in the basement and there is a dogleg at the top of the stairs that would prevent the TV from going to the basement. I got a 60" down there. It was probably as big as i could possibly get down there.

[budm]

Re: element eldft551 not turning on

So the 380VDC is there and stays there after the 5/12/24V fade away, if that is the case then the PS_ON is OK, then we need to look at the 5/12/24V power supply section.
It the power supply MAGMEET MLT199TL?
There are a bunch of caps under the heatsinks also.

[cashkennedy]

Re: element eldft551 not turning on

Yes it is a MAGMEET MLT199TL.

There are hidden caps under the heatsink on the secondary side (and 1 tiny startup cap hidden under the heatsink on the primary side). All the hidden caps are JH and all look as unbulged as the caps outside the heatsink that you can see... All the JH caps have extremly deep / agressive vent lines in what looks like some insanely thick material for a cap can to be made of (maybe the chinese think the cap will last longer if they like imprison the insides within a very thick steel can).

Because the 12v, 5v, 24v voltages all turn off im more expecting this to be an issue with some IC on the power supply, but you know way more then me.

[budm]

Re: element eldft551 not turning on

That why I am asking if the 380Vdc is there and does not drop out when the 5/12/24V drop out, that is the key point I need to know since the PS_ON (STB) is used to turn on the PFC Voltage booster circuits AND the 5/12/24V power supply section, if the 380V is there but the 5/12/24V disappear, then we can check the 5/12/24V power supply section next. But if the PFC 380V also drops out, then we need to work on the PFC circuits since the 5/12/24V power supply section requires 380Vdc to run.

[cashkennedy]

Re: element eldft551 not turning on

Yes the 380 stays on constantly once the tv is "on" with blue led lit. I will reconfirm that again tonight (im at work now).

Since i now have the power supply unscrewed ill also take some pics of the bottom of the PSU and get the p/ns of any IC's on the secondary side.

There isnt that much under the secondary heatsink. Other the the caps i think there is just some ferrite inductors.

[tom66]

Re: element eldft551 not turning on

If you need a schematic, I'm receiving a disk with about 2,000 schematics from a friend. It has an MLT199 schematic on it. It'll take me a few days to get it all uploaded... , I'll try and prioritise the MLT199.

[budm]

Re: element eldft551 not turning on

That will be great Tom!
Ok now we can concentrate on the 5/12/24V switching power supply section.
There is a gray rectangular cap between the big transformer and the two Mosfet's on the heatsing that drive he 5/12/24V transformer. Check the value of that cap and the solder joints on its legs.

[tom66]

Re: element eldft551 not turning on

It includes Darfon inverter schematics, Samsung power schematics (new LED and thin plasma too), FSP schematics, Delta schematics, and more.. I think it's from China, the land where "copyright" is a suggestion and not a law.

[cashkennedy]

Re: element eldft551 not turning on

Theres 4 grey rectangle capacitors , 2 in the primary, 2 in the secondary.

I took pics and labeled them:

1) CA17, <I> MMKP82 683K630, no resistance even on 2M (out of range or open)
2) C28, 472J400, has a steady resistance that's rather high
3) C29, 472J400, has a resistance that increases (cap charges)
4) C31, 474J63, has a resistance that increases (cap charges)

Im not sure how else you want them tested , but I don't own an ESR meter.

This is a rather simple board actually / traces are all huge so you can probably make it all out from my bad pics. In the secondary there is 1 IC (markings are melted off I think) and 1 power transistor? ( alpha and omega d452a). The primary has 3 ic's , one on the front (sg3525an) and near that on the bottom of the board (J653a parw) and over by the main cap on the back is a tiny ic (62939)

[budm]

Re: element eldft551 not turning on

Do you have cap meter to read the capacitance? CA17 is the one I am interesting in since it is part of the primary side circuit for driving the 24V transformer.

[cashkennedy]

Re: element eldft551 not turning on

Nope, no capmeter, can I make one?

I remembered you asked about bad soldering joints and all the grey caps are soldered well. There is 1-2 places where the solder is shinier on the board and poorly flowed/ so was possibly repaired in the factory or not fluxed well before the board was soldered, but im pretty sure the person who had the set before me didn't fool with it.

[budm]

Re: element eldft551 not turning on

Your meter does not have built-in cap meter?
The picture of the bottom side of the board is way out off focus for me to trace out the connections. Can you take the pictures in segments so I can join them together into big picture? I still need good picture of the whole bottom side.