LG Flatron W1934S

[selldoor]

Re: LG Flatron W1934S

OK Let us start that again

All the time it was on mean all the time the screen had some backlight on it... when it disappeared I turned off the monitor. Guess it last one minute.Should I leave it plugged longer?

Set up your PC with the vivid picture - check that if left this will stay on for 10 mins.
Start again - Set up your PC with the vivid picture then connect the W1934S and switch it on.
You say it will then come on, flash something, go black,come back on for up to one minute then go black.
Is that correct?
You must then just leave it as it is -do not switch anything off or unplug anything.
THEN try the torch test.
It may be that that is what you did but it has lost something in translation.

Also I dont think you answered this question:
does the power light led come on, stay on, flash, change colour.

[champzzz]

Re: LG Flatron W1934S

I did exactly what you said now.
When the screen went black I flashed the torch there and I got those 2 stripes I got in the very begining of this tread. They were there, like a background, really dark, only seen with the torch!
That's what I got to do or am I missing something?

The power light still blue, like there's nothing going on...

[selldoor]

Re: LG Flatron W1934S

You have got it exactlly right. It may not mean much to you now, but these are important tests when troubleshooting a monitor. Nothing more to suggest until you get use of a meter.

[champzzz]

Re: LG Flatron W1934S

Ok, thank you so far.
Now, all I've got to do is get a multimeter... hope soon I get it!

[champzzz]

Re: LG Flatron W1934S

Here I am, again.
I got the multimeter... now I need you to teach me how to handle this!
You can see how the multimeter looks like in attachment.

Hope you can help me soon!
Thank you.

[selldoor]

Re: LG Flatron W1934S

Hi - sorry - missed seeing your post, anyway ,hopefully you have been practicing with your meter.
Is it callibrated correctly - on zero when on and probes not touching.


A few very important things to remember.
Measure Voltage with power on
Measure Resistance with power off ( and wait 5 minutes if power just off)

Do not touch heatsinks when power is on.

See the black line zig zag across the power board?
one side (with the BIG blue cap on) is lethal mains voltage. Most of the other side is low voltage except for the output from the inverter transformers.Large black rectangles (one is at T501) and the 4 little white sockets which can carry around 2000volts.

ANYTHING you dont understand - ASK

Ok start with some simple tests.

With the power off - and the board can be connected or not with your meter set on maximum ohm measurement, test the inverter transformers.
T501 and T502 are the inverter transformers. Pins 7 and 8 are the secondaries on each one. Measure the resistance between pins 7 and 8 of T501 and between pins 7 and 8 of T502. They should be about 1K, and must match to within 3%. ( Do the test twice to check your results) then post the numbers

[champzzz]

Re: LG Flatron W1934S

I have a question, which of them are the + and -? (pins 7 and 8)

[selldoor]

Re: LG Flatron W1934S

Doesnt matter for resistance measurement

[champzzz]

Re: LG Flatron W1934S

Okay, I ran the tests twice.

Here are my results:

T501 and T502 = 2,5 ohms each.

The image shows what I got measuring.

[selldoor]

Re: LG Flatron W1934S

Hi - ive been looking for instructions for your meter. Cant find any. May have misled you on setting zero - With it on Ohms and touching the leads together it should go to Zero.
If the setting the meter was on was for full deflection on 1000 ohms then that would be perhaps 260 which seems a bit low but if they are both the same that is the important thing. Just try again using the next setting X100 -it will probably just go right across off scale.- just do it the once.

[champzzz]

Re: LG Flatron W1934S

Okay, set it to X100 and on both the number was 10 ohms.
When set to X10 I got 100 ohms on both!

[selldoor]

Re: LG Flatron W1934S

Have to confess I dont know what that means did you get any instructions with the meter.
I have been looking at the service manual which is supposed to be for the w1934s but it doesnt seem to match up (Not unusual) Ill look again tomorrow. Can you read any numbers on top of the inverter transformers and I will try and get some info on them.

Next thing to check is the low voltages on the connector that goes to the other board.
I will post a picture of the connector. You will need to put your meter on volts DC10The board should be connected to the mains and switched on but not connected to anything else. Although you are measuring low voltages as I have explained earlier part of the board is still at high voltage so dont touch ANY of it with your hand.
There are six pins, the middle two are ground so you can put the black negative lead on either of those two then touch the red positive lead onto each pin in turn and record the result, keep it on for a second or two to see if the voltage stays the same or fluctuates. If you think it is easier and you can see the connector on the back of the board test it there. If you want you can do a dummy run without the power on- you wont get any usable readings but you will see how to manage placing the probes and reading the meter at the same time.

[retiredcaps]

Re: LG Flatron W1934S

Okay, set it to X100 and on both the number was 10 ohms.
When set to X10 I got 100 ohms on both!

10 ohms X100 = 1000 ohms or 1K.

100 ohms x 10 = 1000 ohms or 1K.

Using the X100 scale gives a bit more precision.

Using X1K would yield even more precision since the needle will be around the number "1" on the green ohm scale.