Samsung SyncMaster 2493HM black screen with power

[thirdoff]

Hello. My Samsung 2493HM will power on but has a black screen.
Working great for a while, it even sometimes works for a long time but then the screen goes black.
This is what I do know;
The Blue LED is solid when this occurs.
Sometimes while it's black, a clicking/ticking noise will start in no particular pattern. The noise may be coming from the speakers but I cannot tell for sure.
I have opened the case, inspected the caps and they are not visibly swollen. I know this might still be the issue I just want to move in the right direction.
I shined a flashlight on the screen and I see no picture/color.
One of the leads to a speaker cone was broken so I soldered to repair but I do not think this is related. The speakers work at all times.
Before I start replacing the wrong (or right) parts I was hoping for the shared expertise and experience here to help me in the next direction of troubleshooting and repair.
Thank you.

[retiredcaps]

Originally Posted by thirdoff

The Blue LED is solid when this occurs.

The solid blue led indicates that the power board and logic board are likely to be working okay. When the screen goes black, this suggests something wrong on the inverter board.

The standard procedure here is to post clear focused pictures of all your boards using the manage attachments functions so the pictures are attached to this forum. Please do not post inline because it slows down the loading of pages.

After you have posted the pictures using manage attachments, we can suggest test points or see if the caps on the inverter board are known bad series.

[thirdoff]

Photos Attached

[PlainBill]

Originally Posted by thirdoff

Photos Attached

The pictures are clear enough to give me a point to check. On the fourth picture (inverter) it appears the third pin from the top is the On/Off control line; the fifth through ninth are ground. Measure the voltage on that line when the backlights have gone off. It should be about 3.3 volts. If it is, you have a 'two seconds to black' problem. I believe replacing the two caps on the inverter would be the first step.

PlainBill

[retiredcaps]

Originally Posted by PlainBill

If it is, you have a 'two seconds to black' problem. I believe replacing the two caps on the inverter would be the first step.

I agree.

Normally, I would go for Panasonic FR/FM, but both are out of stock at digikey so FC would be the next choice at

http://search.digikey.com/scripts/Dk...name=P10301-ND

Or you can buy from the badcaps.net store and support this site with

http://www.badcaps.net/store/product...roducts_id=114

[thirdoff]

Thank you. I will set it up where I can power on while open. Or I may just change all the caps. I wanted to be sure as the screen may flicker for several minutes before going out. It also may run and be lit for hours or days before it goes out. It does not go out right after turning on. Once it's out - it seems to stay out for a long time. It does not come on and then turn off after 2 seconds ever.

[jetadm123]

I would also replace the two yellow Sam Young caps on the inverter board, since that brand is not the most reliable.

[thirdoff]

Sorry, picture 4 shows both boards and I can generically troubleshoot components but I have no idea the location you refer.
Sorry, I am ignorant to these monitor's components.

[thirdoff]

So the invertor board is the one in picture 5? I know what an invertor board looks like in a notebook and that looks most like it?

[jetadm123]

Yes, pic 5. Two yellow caps, marked NXH 470uf 35V.

[thirdoff]

Thank you. I will replace the two caps on the inverter board (470uF 35V).
I will use and support this board unless I can find it locally over the weekend or with cheaper shipping. I will read up on your brand recommendation.
THANKS AGAIN! (Yes I am shouting because it's exciting to see educated, responsive community support!)

I will be back with the results if it will help someone else.

[thirdoff]

Replaced the two 470uF 35V CAPS on the invertor board. The ones from digikey were too long but they worked any way. They did not however fix my problem. The screen is black, LED is still solid blue and I still here the clicking/ticking. It hasn't light up at all now but the noise is the same. I will try to record it and attach.

[thirdoff]

The backlight just came back on. It is still intermittent like it was. What troubleshooting point is next? Again all the CAPS look great. I will record the sound the next time it goes blank. The sound is consistent and only with the blank screen. Every time I try to record the sounds stops and the monitor works, maybe I found the fix! (not really) ...I'll just set up constant recording and it appears it will work forever not allowing me a chance to record.

[retiredcaps]

1) Check for poor solder joints on the inverter board.

2) I wonder if that clicking sound is arcing? That is, poor ccfl or burnt out wiring to/from the ccfl?

edit: See

http://s807.photobucket.com/albums/y...klight%20lamp/

for example pictures

[jetadm123]

The large ribbon cable that connects the power board to the logic board, with everything connected and powered on, can you take a voltage reading of every point on that cable connector and post your results?

[thirdoff]

The monitors works with no noise and full display when its working.
The clicking sounds like it is coming from the bottom right of the monitor. I swear the moment I shut down my recording device, the monitor went blank and started clicking. It is blank again after working for about 24 hours, I see it is in power saving mode ok, but when it wakes up it is blank. I got it recorded! The attached zip file contains a recording of the clicking and an amplified version. I will also get readings on the ribbon cable.

[thirdoff]

I should also add this started the night of a storm and a power outage. I do not know if it is related.

[alexanna]

Two seconds to black is just a very general term to describe a problem, it can be a lot quicker than two seconds. On some monitors you may not even be able to see through the dark LCD screen
Have you or can you verify that the backlight on voltage stays at about 3.3V when the lights go out?
PlainBill identified the pin to check.

[thirdoff]

Thank you, I still need to set it up so I can check the test points. I was not clear to where the "pins" were located on the inverter. On the white/blue cable or ???...
I was originally hoping just switching the caps would help. Does the noise reveal anything?

[pumady]

Hi thirdoff, do you get the solution? My 2493HM monitor has the same problem, looking forward your suggestion.