Monitor LG Flatron W1934S 2 seconds then turned off

[francesco3000]

Hello everyone sorry for the language is not perfect
can you help me if I have a monitor that lgw1934 and turned on 2 seconds then goes off in another post as I tried to pull one at a time, CCFL connector capacitors look good

[smason]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

When you say it goes off, do just the backlights go off, or the whole monitor (power led)?

Do you have a multimeter?

[francesco3000]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

Meanwhile, thanks for the reply, turns off the monitor but the light is on indicating that stays on then just turn off the button and turn it on again and he turns on for 2 seconds
you have a multimeter

[retiredcaps]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

Possible causes of "2 seconds to black" can be

a) bad caps
b) bad ccfls and/or ccfl wiring
c) bad inverter transformer
d) bad ccfl sense circuitry

All are discussed in more detail starting with post #13 and #14 at

https://www.badcaps.net/forum/showthread.php?t=10419

[francesco3000]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

hello and thanks for the reply, the problem is that the backlight turns off the power LED stays on
capacitors do not seem inflated.
the primary measure all 0.5 ohm transformer, the secondary measure 618ohm.
resistances are all ok
and can do some measurements on this chip oz9938gn-ic I know that this takes the security chip
I can give a hand to do some testing
I am attaching photos
possibbile would find a wiring diagram

[lcdman]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

Hello,

Heres a service manual .PDF on this monitor. Hopes this helps you!

A Fellow 1/2 Italian
lcdman

[francesco3000]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

hello
Thanks and we'll try '

[ipman]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

I've got one of these monitors.
It was the clasical "2 seconds to black" simptom.
When I opened it, somebody resoldered some connections, but according to the former owner, it was not repaired before
Found 2 bulging caps, Ltec brand.
Then I've found this thread, opened the service manual and these two caps cannot be found. Instead of these 1000uF/6.3V general purpose caps, the manual listed a 1000uF/10V low-esr cap marked as C812. The picture above confirmed that it was an empty space instead of the second cap. They measured an ESR value 6 times more than they should have, and they had around 300uF instead of 1000 nominal. Replaced with an Rubycon HM 1200uF/16V salvaged from a junk motherboard.
C501 and C810 were originally 470uF/25V, but they were replaced with 1500uF/16V Rubycon HM which survived intact, to my surprise. They show the capacity and ESR in spec. Replaced with Samxon GF (I know, bad series, but cannot find something better. Luckily, they are away from heatsinks.)
Now the monitor is working again as it should be.

[aziiiz]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

problem of 2 seconds then it goes DARK

I reversed the CN501 & 502 by CN503 & 504.;

It works fine ...

[ipman]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

Another one repaired.
Story: bought the monitor as a bargain. According to the former owner, afther heating-up, backlight flickered until went totally dark. Bought as defective.
Opened the monitor, replaced two 470uF/25V low-ESR Hermei caps with Samxon GF, one 1000uF/10V Jackeh lowESR with Samxon GT. Nothing wrong with them as measured with ESR meter tough.
Resoldered a lot, what seemed to be cold joints: inverter transformers, caps, even the HV connectors on PCB.
Tested on bench with back cover removed, everything fine.
Assembled it, 2 seconds working, then black, but image was there.
Dissasembled again, worked without back cover!
The back panel was pushing against one HV pigtail between PCB and lamps ... The monitor is working again now.

[PlainBill]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

Another one repaired.
Story: bought the monitor as a bargain. According to the former owner, afther heating-up, backlight flickered until went totally dark. Bought as defective.
Opened the monitor, replaced two 470uF/25V low-ESR Hermei caps with Samxon GF, one 1000uF/10V Jackeh lowESR with Samxon GT. Nothing wrong with them as measured with ESR meter tough.
Resoldered a lot, what seemed to be cold joints: inverter transformers, caps, even the HV connectors on PCB.
Tested on bench with back cover removed, everything fine.
Assembled it, 2 seconds working, then black, but image was there.
Dissasembled again, worked without back cover!
The back panel was pushing against one HV pigtail between PCB and lamps ... The monitor is working again now.

Congratulations. I shudder to think how long it would have taken me to figure that problem out.

PlainBill

[ipman]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

It took me a full day to figure out why it was working without back cover but not assembled. I cannot figure out how many times I dissasembled and reasembled the monitor tough.
And another day to measure all caps and find replacements locally.
Anyway, there was no rush.

[djmurati]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

tanks ipman......... I have like same problem LG flatron w1934s now finish......
You helped me a lot THANKS take care fully.....

[LaGGER]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

I have problem with LG W1934s
2sec and go off is solved but not its blinding maybe problem is a DVD ans speakers with magnet ofc I go to degaus monitor and blinbing is lower

[LaGGER]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

Sry for my bad english...

2 sec go dark prob is solved by manual power on-off backlight but few months later backlight flashing IDK why whats the problem maybe speakers and DVD whic is almost 2-5CM placed from the monitor speakers are with magnet

[palamattam]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

I had the same problem with my LG flatron w1934s,display showed momentary and vanishes. I tried many online forums and learned to open the monitor. The capacitors showed in good condition.Contacted LG and one day the serviceman came to my house.He inspected the monitor and told me the lcd display is damaged and will charge apxy Rs 4000/-.There was no point spending that amount,instead I can buy a new monitor. While checking the power supply I found 600volt supply to the display is off.The power board components are surface mount and impossible to repair at home. Surveyed Lamington Road at Mumbai. One shop had separate LCD inverter board with connection details which costs just Rs.200.I connected the board and Lo the monitor worked !!

[selldoor]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

LaGGER

1, Do not hi-jack other threads
2, Do you have a W1934S or a W1932S
3, The picture you posted in the other thread is useless
unless you post a much better one we can not help

[Jastreb]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

Sorry for digging out the old thread but since the problem is the same Ill use this one.

Problem : LCD monitor LG Flatron W1946S turns on briefly then goes off. Backlight goes off, but power light is on, so as indicated here, Ill check on caps, wiring, invertor and ccfl's.

Reporting back with solution and images.

Thanks to lcdman for the pdf repair guide.

[borbs]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

Sorry for digging out the old thread but since the problem is the same Ill use this one.

Problem : LCD monitor LG Flatron W1946S turns on briefly then goes off. Backlight goes off, but power light is on, so as indicated here, Ill check on caps, wiring, invertor and ccfl's.

Reporting back with solution and images.

Thanks to lcdman for the pdf repair guide.

Hi Jastreb, i have same problem with that monitor. Did you fix yours? What was the problem?

[ANIBALYMARTA]

Re: Monitor LG Flatron W1934S 2 seconds then turned off

pin 3 of ic 501 (OZ...) to gnd. If timer no 3v = no lamp check.