LG W2453V Picture Dies After 2 Seconds

[flafson]

Hi,

So i have a problem with an LG W2453V, i connect it, it turns on and shows a picture and after about 2 seconds the picture turns off but the on button light is still on. If i unplug and reconnect, the same will happen again.

After reading a bit and coming across this place i found out the problem is likely bad caps.

I took the monitor a part and took some photos of the power board.
At first glance it looks like the small 33 uF has leaked but is it enough to cause that problem? The other caps look alright, no leak, no weird shape.
Now, after a while of looking at it i noticed that there is also some white stuff below the big 68v caps, is that normal? I read that they rarely break.

Another possible problem that i found, if you look at the back photo i took, the back side of one of the big pieces (i think it's inverter?) is really black, kinda like it was burned, also has some burned smell to it. I assume it's not normal, not sure though.

I looked on ebay and a kit for the normal caps i need goes for $10 but i also found used from china some complete power supply board for $22. Might be more cost effective to get the whole board if indeed it's more than the normal caps, only problem though, the caps it will come with are the same standard ones it came with and plus shipping is probably 2-3 weeks.

One small note i was wondering about, the board has lots of small blue things to it which kinda look like M&M, about half of them look like they leaked the white stuff. I've seen some photos of the same board before and they all have that white stuff leaking from them, is that normal? I guess so, but why?

Any ideas?

Thanks.

[Rtech]

Re: LG W2453V Picture Dies After 2 Seconds

If the 33UF cap is leaking then you will need to change it.The 'white stuff' under the big caps and on the 'blue M&Ms' (which are caps as well)...is Glue and unless it has gone yellow,and can become conductive in that state, it should not be a problem.The Black part is under the Inverter transformer,and at each end of it are two pins.You need to measure the Resistance between each set of two pins and advise.....they should be within 3-5% of each other.

[Mrx3750]

Re: LG W2453V Picture Dies After 2 Seconds

As I learned from my Viewsonic, if you change the caps and it still isn't staying on, check the CCFL's. You might want to read the 2 seconds to black sticky for more info.

[budm]

Re: LG W2453V Picture Dies After 2 Seconds

The inverter transformer looks like it runs hot, you can see the PCB underneath the transformer is blackened, so check the resistance readings of the HV sides as suggested by RTECH.

[flafson]

Re: LG W2453V Picture Dies After 2 Seconds

First of all, thanks for all the helpful replies.

Now, i'm a noob to this "business", so the way i understand it, i need to buy a digital multimeter with auto range, there are hundreds of those on ebay, are they all ok? Do i need to look for something more specific?
And then check the ohm readings between the upper left/right to the lower left/right to makes sure they are within 3-5% of eachother?
Another noob question, when i hook the multimeter up, the power should never be connected to the board, correct?

[Rtech]

Re: LG W2453V Picture Dies After 2 Seconds

A mutimeter ?? yes..need not be Auto Range...Then check the resistance BETWEEN the upper L/R pair, and then the lower L/R Pair ..each pair is separate, so no readings are required between the upper and lower pair of pins,Finally NO Power to the Board !!!!

[flafson]

Re: LG W2453V Picture Dies After 2 Seconds

So i checked the resistance (it's the one that uses the omega sign on the dial, i think) and it gave me 1.019 on the first pair and 1.023 on the other pair. I guess that means they are well within the 5% and are in good working condition?

I already ordered some replacement caps, hopefully ill be able to solder them.

[Rtech]

Re: LG W2453V Picture Dies After 2 Seconds

Transformer readings are good,if the caps do not work,and I suspect they will not,then you are looking at possible problems with the lamps themselves..let us know !!

[budm]

Re: LG W2453V Picture Dies After 2 Seconds

Yes the lamps may be the problem. There are two dual MOSFETs (the SMD devices with 4 pins and big tab on top) that drive the high voltage transformer, P/N? We need to check them too. You can also make two test lamps using old CFL.

[flafson]

Re: LG W2453V Picture Dies After 2 Seconds

English please? Haha.
If it's not the caps (which i will test once the new caps come) then it would make more sense to buy a new (used) board for $22.

[budm]

Re: LG W2453V Picture Dies After 2 Seconds

See the picture, you can have board problem or lamp problem.

Bad lamps:
http://s807.photobucket.com/user/bud...?sort=3&page=1

[kaboom]

Re: LG W2453V Picture Dies After 2 Seconds

Also, there are a total of 8 ceramic caps near both lamp connectors. These "ballast" caps, by virtue of their capacitive reactance, limit the current to the lamps.

Sometimes, they start to break down. Only under full operating voltage, this can cause excessive lamp current, leading to the lamp OCP ckt operating and killing the backlights.

It's important to use good caps here, they handle quite a bit of reactive power, despite the lamps only being a few watts apiece.

Since they tend to act up only at full voltage, it's pointless to check them w/ a meter. Just replace with equal value and higher voltage. Same type- NP0.

[flafson]

Re: LG W2453V Picture Dies After 2 Seconds

See the picture, you can have board problem or lamp problem.

Bad lamps:
http://s807.photobucket.com/user/bud...?sort=3&page=1

I see what you mean, from closer look it looks like red wax in there.

[N3trox]

Re: LG W2453V Picture Dies After 2 Seconds

Sry to bump this up but i got the same screen with the same problem no caps visualy busted brown under transformer.. did you find what was wrong with it?

I just opened mine so gonna try and test see if i can find the problem iam new to testing components but iam here to learn ^^

[N3trox]

Re: LG W2453V Picture Dies After 2 Seconds

ok its been a while finally found the problem 2 of the CCFL where dead so iam now planning to convert to led for the fun of it to just see how it will workout.

Now i need your help to figure out where i can "steal" 12-19V since thats what the driver needs to function there is a Capacitor that is rated 16V (the 4 caps next to eachother) can i just solder my + wire to it and ground to any ground and be happy with it ?

Sorry for double posting

[Davi.p]

Re: LG W2453V Picture Dies After 2 Seconds

16v Cap doesn't mean it's applied 16v on it, but always less, your board is working so test the output or watch for markings on it near the output connector.

[N3trox]

Re: LG W2453V Picture Dies After 2 Seconds

So if i find a connection that gives out 12-19V can i just solder the positive wire to that point and then the ground to the nearest one ?

About the Cap i knew that its max is 16v if it measures 12-16V can i just solder the positive to the caps positive and be done with it or do i need to cut the connection there or something else before?

Thank you for the help Davi.p

[Davi.p]

Re: LG W2453V Picture Dies After 2 Seconds

I see in the bottom's photo that in the output connector is written 22v and 5v, i'ts strange for a 5v to use 16v caps, usually are 10v, then you cannot make the modify unless you put a linear regulator like lm317 or better (?) but in this way the energy efficency of the leds will decrease..
for energy save purpose you must maybe desolder the square brown/magenta fuse F201 near output connector, i don't see bottom view well so i'm not sure

[budm]

Re: LG W2453V Picture Dies After 2 Seconds

C301 is the last filter for the inverter power supply, you can get the power right at the two legs of the cap, but you must use some kind of current limiter to feed your LEDs. The little rectangular fuse is for the main logic board b+.
You also meed to remove the b+ jumper wires that feed the inverter circuit so the inverter will be disabled.

[N3trox]

Re: LG W2453V Picture Dies After 2 Seconds

C301 is the last filter for the inverter power supply, you can get the power right at the two legs of the cap, but you must use some kind of current limiter to feed your LEDs. The little rectangular fuse is for the main logic board b+.
You also meed to remove the b+ jumper wires that feed the inverter circuit so the inverter will be disabled.

Ok, as for the LED it has a driver so think i only need to step down the voltage and it should work.

As for cutting the jumpers at B+ where is that after the cap near the transformer? Iam new to all this sorry for the newb questions ^^

Thx for all the help appreciate it