Element ELCHW402 - Will not turn on!

[Misfitjah_420]

Re: Element ELCHW402 - Will not turn on!

I have this same TV and I am a certified Industrial Electronics Technician, I went through all the normal troubleshooting procedures and came to the conclusion the main board has failed so I replaced it now the red standby light isn't coming on, and I have no voltages on any of the connectors. I have mains coming up to the contacts of the relay but the relay is not closing. I have tested most of the components in the main board and they all check out fine. Any ideas of where to go now? I originally had the same issue as the first poster, had the 4.5v on the 5vs and 5v-s, roughly 2 on the STB pin and nothing on the others. I checked the big 1000v blue cap and its reading 47nF which is fine.

[selldoor]

Re: Element ELCHW402 - Will not turn on!

You need to decide what you are trying to fix - you dont tell us a lot and half of it is not relevant to one board.
What tests did you do that made you decide it was a main board fault.

[budm]

Re: Element ELCHW402 - Will not turn on!

I have this same TV and I am a certified Industrial Electronics Technician, I went through all the normal troubleshooting procedures and came to the conclusion the main board has failed so I replaced it now the red standby light isn't coming on, and I have no voltages on any of the connectors. I have mains coming up to the contacts of the relay but the relay is not closing. I have tested most of the components in the main board and they all check out fine. Any ideas of where to go now? I originally had the same issue as the first poster, had the 4.5v on the 5vs and 5v-s, roughly 2 on the STB pin and nothing on the others. I checked the big 1000v blue cap and its reading 47nF which is fine.

So let me get this correctly, you do have standby power supply voltage feeding the main board. The new does not show any indicator light but the old one does?
You have about 2VDC at the STB (PS_ON) pin, then you should check the dc Voltage RIGHT AT THE TWO LEGS OF THE MAIN FILTER CAP to see if you do have about 360~400VDC on that filer cap, if not you will need to fix the PFC Voltage booster circuit.
Post good clear pictures of the back side of YOUR TV and the boards of YOUR TV.

[d_robers]

Re: Element ELCHW402 - Will not turn on!

does it matter witch way i solder the new film capacitor in the board? i cant remember witch way the old one was turned and didnt know if polarity made a difference.

[Agent24]

Re: Element ELCHW402 - Will not turn on!

No, it does not matter, those capacitors are not polarised.

[de_bronzeprince]

Re: Element ELCHW402 - Will not turn on!

hi guys...have the elchw402 replaced with new poly-film cap..no joy..was wondering if someone may be able to translate the solution of pineapple to me...what exactly did he discover??? and what is meant by "the smps isn't functioning properly"??? also if someone has another fix aside from re[placing the blue cap please send it my way... thanks !!!

[d_robers]

Re: Element ELCHW402 - Will not turn on!

No, it does not matter, those capacitors are not polarised.

thanks I wasn't sure but i didn't think that it mattered

I replaced the blue film compacitor but it didnt help in my case. before and every once in a while I could unplug the cable marked as A in the pic below and when the back lite lit up i would plug it back in and the screen would come to life but i never could get the two clcks from the relay with out unpluging cable A first. and when I unplug cable marked B in the pic I would get the two clicks every time that I pluged the main power cord in but the blue led would come on for just a few seconds and then it would turn back red but if I leave cable A and cable B unpluged at the same time the tv will power on with sound . what else could it be?

[Agent24]

Re: Element ELCHW402 - Will not turn on!

Unfortunately, unplugging and reconnecting cables while the set is running does not really prove much, and is likely to cause damage to other parts.

The only thing I can think is that by unplugging some things you reduced load on the PSU and it was able to start up, so perhaps the PSU has dying capacitors or some other fault... But it's hard to say.

We really need a better test, measure all the voltages and control lines\signals from the PSU etc, see if any are incorrect\missing etc.

[d_robers]

Re: Element ELCHW402 - Will not turn on!

ok i will test it again and post the results later today i left my meter at work. thanks for helping me. i could buy another tv but im having too much fun with this

[3redlines]

Re: Element ELCHW402 - Will not turn on!

What solved the problem for me was C811 & C812 in the power supply (top left corner), 10uf@25v. This is in the power source for N831.

[newuser65]

Re: Element ELCHW402 - Will not turn on!

A friend brought me this same TV with the same problem, hoping I could fix it for them. Watched a you tube video like someone else said,before finding this website No blown caps (except c842 appears swelled on one end) like everyone else. The one on this set is buldged on one end, all others look good. I ordered the cap from Digikey moments ago, so we'll see.
Didn't think I should start a new post with the same TV and same problems.
Digikey is out of part# 399-5982-ND so I ordered part# 495-3799-ND. Guess we'll see if I did good in a week or so when cap gets here.
I did my homework and took some pic's of board and checked a few readings.

All boards hooked-up (DC/V) No Boards hooked-up

GND 0.00 GND 0.00
GND 0.00 GND 0.00
STB 2.08 STB 0.00
5vS 4.77 5vS 4.79
5vS 4.77 5vS 4.79
12v 0.01 12v 0
12v 0.01 12v 0
GND 0.00 GND 0
BR1 0.00 BR1 0
SW 0.00-0.01 (bouncing back/forth) SW 0
GND 0.00 GND 0
GND 0.00 GND 0
5vM 0.00 5vM 0
5vM 0.00 5vM 0

121.8 AC/volts both sides of main fuse. My meter does have a diode test but doesn't read what I think others are (nF) see manual pic attached. Can anyone explain in (simple terms) what it means.
Any ways I tested the big blue cap in c842 (in circuit) with the tv plugged in (won't power on) and the reading was 520 unplugged the tv and it read 456
With all other boards unhooked it read 459 both plugged in and unplugged.
$1.41 for the part $3.40 shipping = $4.81 fix
Unless something changes I'll post back after I get it changed out.

[dick_barton]

Re: Element ELCHW402 - Will not turn on!

Disconnect the power supply from the main board and connect a 1K resistor between 5VS to (I believe SW). Then check that 5M and 12V are present. If they are then it would appear to be a main board fault.


Worth viewing:-
http://www.jestineyong.com/video-mis...d-tv-elchw402/

[newuser65]

Re: Element ELCHW402 - Will not turn on!

Disconnect the power supply from the main board and connect a 1K resistor between 5VS to (I believe SW). Then check that 5M and 12V are present. If they are then it would appear to be a main board fault.


Worth viewing:-
http://www.jestineyong.com/video-mis...d-tv-elchw402/

That's the video I was referring to.
Are you saying to leave the power supply disconnected and test the 5vM and 12v ?

[dick_barton]

Re: Element ELCHW402 - Will not turn on!

To test the capacitor you would need a capacitor checker which lots of meters have today.

Yes, unplug the connector from the power supply board that goes to the main board, connect the resistor between the two points and switch on power to the set.

Edit.
Budm has corrected me.
And it looks as though the power supply is at fault.

[budm]

Re: Element ELCHW402 - Will not turn on!

STB 2.08 is the PS-ON
BR1 0.00 is the Dimming control.
SW 0.00 is the BL-ON
So right now you do have 5VSTBY and the PS-ON signal but no switched 5V or switched 12V.
The board has PFC so you need to check if you do have close to 400VDC between the two legs of the main filter cap in the hot side or not, that will be the first step.
BTW, does the STB change state between 2.08V and <1V when power switch is activated? The 2.08VDC is on the low side so that may be the problem too.

[dick_barton]

Re: Element ELCHW402 - Will not turn on!

It appears as thougth the PFC voltage is derived by a push-pull pair of mosfets with it's output connected via that 47nF capacitor (which appears to go faulty) to the primary of the transformer.

[budm]

Re: Element ELCHW402 - Will not turn on!

It appears as thougth the PFC voltage is derived by a push-pull pair of mosfets with it's output connected via that 47nF capacitor (which appears to go faulty) to the primary of the transformer.

No, it is just a typical PFC circuit with single power MOSFET. The blue cap is the DC blocker/coupling cap for driving (Half-bridge) the transformer T831.

[newuser65]

Re: Element ELCHW402 - Will not turn on!

STB 2.08 is the PS-ON
BR1 0.00 is the Dimming control.
SW 0.00 is the BL-ON
So right now you do have 5VSTBY and the PS-ON signal but no switched 5V or switched 12V.
The board has PFC so you need to check if you do have close to 400VDC between the two legs of the main filter cap in the hot side or not, that will be the first step.
BTW, does the STB change state between 2.08V and <1V when power switch is activated? The 2.08VDC is on the low side so that may be the problem too.

400VDC ??? at best I'm reading 64.2VDC on either of the screws you showed as the PFC MOSFET...???
The STB stays at 2.08 and 2.09 VDC weather doing nothing, pressing the power button on the TV itself or trying the remote.
And yes the Relay does click but only once when 1st supplying power to the board.

[newuser65]

Re: Element ELCHW402 - Will not turn on!

The blue cap is the DC blocker/coupling cap for driving (Half-bridge) the transformer T831.

The one that you said "don't look good" is what I had ordered already in hopes it's the problem like most others have had. Seeing it was buldging on the one end pretty bad.

[budm]

Re: Element ELCHW402 - Will not turn on!

400VDC ??? at best I'm reading 64.2VDC on either of the screws you showed as the PFC MOSFET...???
The STB stays at 2.08 and 2.09 VDC weather doing nothing, pressing the power button on the TV itself or trying the remote.
And yes the Relay does click but only once when 1st supplying power to the board.

It is either you are measuring it wrong by using the wrong GND ref point such as chassis for your meter or the meter is bad.
When you measure DCV in the HOT side of the circuit, you have to use the negative leg of the main filter cap as the GND ref. for the meter.
So check the DCV again BETWEEN THE TWO LEGS of the main filter cap.