LG w2241s 2sec and then black

[selldoor]

Re: LG w2241s 2sec and then black

Hi - Vince they will be - except its a an EEL 20D in all probability.
He already tested it in an early post - seems ok - I have one here on a board
tests very similar.

[vinceroger69]

Re: LG w2241s 2sec and then black

cool i missed that bit skim reading threads as usuall yes just re read it in post 2.

[selldoor]

Re: LG w2241s 2sec and then black

Please can you post pictures of the bottom of the power supply again.
Do it in two halves so we can give it a good check.

Also dust off the top and check it for burnt components its hard to see a lot of them through the dust.

[budm]

Re: LG w2241s 2sec and then black

OK, the MOSFETs seem to look OK. I notice that the board under the inverter transformer looks like it is over heated (picture #3 on post #1). Even though the resistances look OK. May be should pull the transformer and inspect the bottom side. We also need to locate the BL_ON signal line to make sure it is still present when the lamps black out just to be sure it is not control signal problem. We also need to inspect those 8 ballast caps (small blue caps by the inverter transformer).

[rippergr]

Re: LG w2241s 2sec and then black

I am attaching bottom pictures of board near the transformer and one picture from top of the board with removed transformer.

budm you said that the MOSFET seem ok. Those readings I have are good? I thought they should give me some readings and not infinitive in all pins.
Can you tell me how to check the BL_ON signal.

[selldoor]

Re: LG w2241s 2sec and then black

I think budm wanted a pic of the bottom of the transformer so he could try and see why it is putting out so much heat.
Also can you post a good clear picture of the bottom of the board at the other end- the
solder joints on those 2 big diodes doesnt look good. Also when you resolder can you clean off the flux (Old toothbrush and IPA ) so we can see them clearly
BLON is a pin on that connector from Main board to Power supply. There may be a legend
front or back on one of the boards - again if you do a close up of the back of both connectors and surrounding area budm may be able to tell you which pin it is

[rippergr]

Re: LG w2241s 2sec and then black

Ok I am attaching the bottom of the transformer and the other end of the board where the 2 diodes are.
I tried to clean it although I didnt resolder the diodes this was as it was from the manufacturer.
I hope I understood correct this time

[selldoor]

Re: LG w2241s 2sec and then black

Partly right good one of the transformer doesnt look burnt but budm will know better.
Pic 2 is nearly ok but the "legend" right at the bottom has been cut off if you can do it again with it on - should say things like gnd 12v 5v and so on.

The other picture I wanted was the bottom side of the other board ( Main Board) where the lead from connector P201 goes to. It is on that board that the blon signal will be generated.

[rippergr]

Re: LG w2241s 2sec and then black

Ok I think I've got it now.
Sending you the new pictures

[selldoor]

Re: LG w2241s 2sec and then black

To move on you will need to replace the transformer - pity budm didnt comment yet.

OK Well the blon pin is the third in "INV-on" on one board and just "on"
on the other board.
First test is with it all connected up, meter on vDC20 black probe on a ground screw probe pin 3 on whichever is easiest to get to with the red.
Maybe you have to push a needle into the socket along side the wire and test to that
The test should be done as you turn the set on- report what happens - leave in test position for 10 seconds

[budm]

Re: LG w2241s 2sec and then black

OK, I am surprised that the center section where the Primary winding of the transformer is, does not show any sign of over heat (may be the picture does not show well) so I cannot tell if there is problem with primary winding or not. I will wait to see what you get on the INV_ON signal.

[rippergr]

Re: LG w2241s 2sec and then black

selldoor can you give me a little help.
You told me to check the vdc20 which I don't see it.
Second you said "meter on vDC20 black probe on a ground screw probe pin 3 on whichever is easiest to get to with the red."
Can you tell me where to put the black and where the red probe because I couldn't understand what you wrote.

[selldoor]

Re: LG w2241s 2sec and then black

I couldn't understand what you wrote.

Me neither most of the time

Ok set your meter to read VDC - if it can be set manually set it on 20vDC
if it is autoranging/automatic just leave it.

You need to set the LG so it can be switched on.
On those two boards - Main and Inverter there is a pin that when you turn the set on will receive a voltage signal from the main board ( we hope)

So to test this you put the black probe on a chassis ground / ground screw
( screw that holds the board onto the chassis or a known ground (you could use a pin on the connector marked gnd but you will run out of hands so it better to fix it somehow unless you have a helper.)
The Red probe you have to put on pin 3 from the bottom and hold it in position while you turn the set on.

Having said all that you may not be able to get to the bottom of the boards so you have to test the top of the socket but because it has to be connected up your probes may not reach the pins so you have to put a needle in.
Hope you can follow this - if not I will try again

[rippergr]

Re: LG w2241s 2sec and then black

The readings from the 3 pin are.
When plug it on power it gives me ~0,45 then goes up to 3.3V the lamp is on , goes down to 0.01V lamp is off. Then goes to 3.3V again the lamplights again and then it goes off. The reading remain 3.3V

[selldoor]

Re: LG w2241s 2sec and then black

Ok so two more tests
First if you have all the boards in place can you take a pic of the whole back of the set to show the set up.
Test1 is to carefully take the ribbon cable that goes from the main board to the panel
off at the main board end. ( Careful those long thin cable clips get brittle)
Then try switching on again. Obviously there will be no picture but the lamps might stay on.
Next test you need a resistor 500 to 1 kohm. This time disconnect the cable that goes from the power supply to the main board and on the power supply use the resistor as a jumper from the 5v pin (pin6) to the inverter on - pin- 3.

If you dont have a resistor you can use a 3v cr2025 battery or 2 AA or 2AAA batteries
and connect between ground and the invertor on pin

[rippergr]

Re: LG w2241s 2sec and then black

Here is the picture of the whole setup.
I removed the cable that goes to screen but the problem is the same. after 2-3 seconds the lamps are off.
For the second test if I understood correct I must put the one end of a resistor to pin6 and the other one to pin 3 in the big board not the small one right?

[selldoor]

Re: LG w2241s 2sec and then black

Yes on the big brown board - Power supply/inverter

[rippergr]

Re: LG w2241s 2sec and then black

I can't find a 500ohm resistor can you tell me how to connect it with battery? And what to do when I connect it? I will plug it to power and measure it?

P.S.: I found a 620ohm resistor. Can you explain what should I do when I put it to 6 and 3?

[selldoor]

Re: LG w2241s 2sec and then black

Drat - gone to eat just drew you a nice pic of how to use the battery back in 30 mins

[selldoor]

Re: LG w2241s 2sec and then black

OK pic adapted for resistor if lucky the resistor might just reach across the holes in the scket or if not solder a wire to one end.

Nothing to measure connect it all up then disconnect the main board
on the socket on the powersupply/inverter board jump pins 6 and 3 with a
300-1000 ohms resistor then plug in/switch on the power to the board.

Test is to see if the lights come on and stay on for say 20 seconds.