LG W2243s 2sec to black with beep

[gmpout]

Hello, am i newbie in the world of electronics but willing to learn. just bought a multimeter, soldering iron, desoldering wick etc.

This monitor faces 2 seconds to black problem with a beep coming i think from the inverter transformer (code number on it: SPW-162 LSE u22BH A)
Image is still visible when direct light hit the screen

--replaced the 2x 1000uF and 1x 470uF capacitors just in case, problem persists

-- couldnt test the CCFLs coz i dont have a 5th spare one, but i tried them one by one seperately on every pin, i had the logo shown on 3 of 4, then 2 sec to black again with no beep this time

i need your advice on correctly measuring any values needed coz im still learning.
i also found the service manual of the monitor (attached)

Thanks in advance, Giorgos from Greece, excuse my english

if more pics needed i'll be here

[Phoenix83]

Re: LG W2243s 2sec to black with beep

Try replace those other electrolytic capacitors.
If the image is still visible, you have a prob with the backlight. Some sound coming out from the inverter transformer is ok. If that sounds like sparks, and smell something like ozone, transformer is K.O. (Do not try to measure the transformer with a multimeter, it would probably not survived). On the smaller PCB solded perpendicular to the main PCB should be parts with sign U302, U303. See whether they have cold joints, or are visible bad.
If you have the opportunity try to connect the CCFLs to another source.
Be careful with high voltage


Sorry for my english.

[budm]

Re: LG W2243s 2sec to black with beep

Build two of these lamps to test your inverter circuits.
https://www.badcaps.net/forum/showth...er+testing+cfl

[selldoor]

Re: LG W2243s 2sec to black with beep

You can do a quick test on the inverter transformer.
Power off the board
Set your meter on 2000ohms and test S1 to S2 and S3 to S4
on the attached picture
Did you do the single bulb test in the same socket or each bulb in its own socket?

[gmpout]

Re: LG W2243s 2sec to black with beep

is there a way to measure these U501, U502? cant visually recognize the abnormality!

thanx for the quick respond

[gmpout]

Re: LG W2243s 2sec to black with beep

S1 to S2 = 780
S3 to S4 = 780

i tested each bulb to all 4 sockets. only in 1 of 4 didnt see light onscreen (i think i really did all the cobinations)

thanks again for your quick support

[selldoor]

Re: LG W2243s 2sec to black with beep

Inverter trasnformer is ok - looks like a dud bulb - either test with one out of (or still in)
something else or make up at least one of Budms test bulbs,

[gmpout]

Re: LG W2243s 2sec to black with beep

okay! im gonna try the ccfl test and post any results as soon as possible

[selldoor]

Re: LG W2243s 2sec to black with beep

is there a way to measure these U501, U502? cant visually recognize the abnormality!

These are mosfets tests for these and many others are in the 2 seconds to black guide by retiredcaps - it is a sticky at the front of this forum.
https://www.badcaps.net/forum/showthread.php?t=10419 start at post 19

datasheet is here
http://html.alldatasheet.net/html-pd...SSM9971GH.html

[gmpout]

Re: LG W2243s 2sec to black with beep

did the test on two MOSFETS. set my multimeter on 200ohm and got the '1' value on both 3 tests S-G S-D G-D.
"Most manual multimeters display "1" on the left hand side to indicate out of range"

then i guess i have no shorted mosfets

Thanks again Selldoor

[gmpout]

Re: LG W2243s 2sec to black with beep

This morning managed to dismantle a working Lenovo 17" Monitor and test the CCFLs. looks like the ccfl connection on CN501 pin is the problem, because in the other 3 pins and the monitor worked just fine yeeey!

now i have to deal with a new problem though. my monitor wont open at all, no light on screen, no light or flashing light on led, think i only hear a repeating "TAK" sound from this (photo attached), something with the power board

thought i was making real progress and now that! only happy for a couple of minutes :/

[gmpout]

Re: LG W2243s 2sec to black with beep

just plugged the power on again and ended it up with a tiny explosion and a blown fuse!

I think i should have waited for your instructions first

[selldoor]

Re: LG W2243s 2sec to black with beep

ok may do that when it is working but there is nowhere for the power to go.

On the right hand side of your picture there is a red fuse F802 can you test it.
First power off meter on ohms probe to each side.
Second - power on meter on vdc200 black probe on a ground screw probe each side of fuse with red. (if less than 20v change scale on meter)

[selldoor]

Re: LG W2243s 2sec to black with beep

My last post relates to your earlier post - it should not do that when its working.

What did you have connected up when you switched it on were the boards loose/ touching? touching the frame? what surface are you working on - not a steel bench?

[gmpout]

Re: LG W2243s 2sec to black with beep

everythin i did was on the back "maybe steel" cover of the lcd screen! i was touching the frame! i messed up didnt I? snif

whats the next step if there is any left !?

[selldoor]

Re: LG W2243s 2sec to black with beep

Arghhhhhh!!!!!!!

[selldoor]

Re: LG W2243s 2sec to black with beep

Messed up big time - how lucky are you? despite this, must be fairly as you didnt kill yourself
First thing will be to clean up the mess- remove the fuse and test the green thermistor
for continuity. Can you see where the short occurred - more burn marks?.
I wouldnt want to spend much on it but to do some basic testing will need to replace the fuse- perhaps use a fuse holder with a few spare fuses instead of a fixed one.

[gmpout]

Re: LG W2243s 2sec to black with beep

i think the short occured on C828 ?! on post 12 image no2 its seems burned. is this useful?
i need more guidance on the fuse replacement and/or fuse holder setup

if it a waste of time from now on, i would like to know and not waste your time!
Thanks again Selldoor

[gmpout]

Re: LG W2243s 2sec to black with beep

green thermistor:
with multimeter set on 2000 ohm it showed 0.06
in continuity test it beeped measuring 6.4

[selldoor]

Re: LG W2243s 2sec to black with beep

I did look at the pic but my top to bottom geography is not good and gave up thinking perhaps just the fuse joint.
Anyway that is useful as it could be just the more robust components that have been shocked.
It is difficult to test a blue cap - just do ohms test across it to make sure its not shorted.
Fuse - what I am suggesting is that instead of removing the fuse and replacing
(it is a fuse with legs welded on) just take it off and replace with a fuse holder
like this
http://cpc.farnell.com/schurter/0031...-bb45-00001003

I dont know how much room you have? You can solder it onto the board in place of the fuse or one something like this - a torpedo holder with a wire on each end.
http://cpc.farnell.com/bulgin/fx280/...1-4/dp/FF02318