[SOLVED] SAMSUNG T190

[Lukisek]

Hi everyone,
My second monitor is broken. After few seconds screen disapper and looks like switched off. But when I unplug hdmi from my laptop, and plug it again it works again for few seconds. Tested on 2 another laptops with the same symptoms. It looks like it need to replace some capacitors on power board like @betwixt suggest me in my another monitor. But I don't have every capacitor now. Can you tell me which capacitors should I replace first? Some of them I have, but which can be suspicious most? Thanks in advance for tips.

Photo of the board in attachement.

 

[Lukisek]

Btw. I measured resistance on trafo inverter and they are in a proper range ca. 980 Ohm on 1-2 and 3-4 pins. Checked with documentation of TMS92920CT. Capacitors doesn't look like swollen. When screen is working there is a quiet noise about trafo (yellow one), but when screen turns off on it's own, then noise fell silent.

 

[BradtheRad]

works again for few seconds.

* What do you see onscreen for those few seconds?

* At power-up does it display a logo?

* Does a light turn on to indicate power is good? Does the light shut off when the monitor stops working?

* Can you access settings by pressing buttons on the front of the monitor? Can you quickly choose default settings? Is there any setting that could cause brightness to be minimized?

* Can you feed it video of a different format, or through a different cable? (Example, VGA)

 

[ZASto]

You should open up panel and change CCFLs.
I have a "patient" at the moment with swollen/blown elkos in power supply.
If two of them are 820 uF, just replace them with 1000 uF of corresponding voltage and all of those should be Low ESR type.

 

[stenzer]

Hi,

a picture showing the electrolytic capacitors from the side would be useful, to see if their top's have lifted up.
But to me it looks they have not changed in "size" (from the provided picture), which is usually a clear indication of a faulty electrolytic capacitor.

BR

 

[Lukisek]

* What do you see onscreen for those few seconds?

* At power-up does it display a logo?

* Does a light turn on to indicate power is good? Does the light shut off when the monitor stops working?

* Can you access settings by pressing buttons on the front of the monitor? Can you quickly choose default settings? Is there any setting that could cause brightness to be minimized?

* Can you feed it video of a different format, or through a different cable? (Example, VGA)

So:
1) I saw my laptop screen, the same what was on the laptop.
2) Yes, it displays logo every power-up.
3) No, only backlight stop working.
4) Yes, I've tried this with no result.
5) No, I don't have VGA (only DVI with plug for HDMI)

You should open up panel and change CCFLs.
I have a "patient" at the moment with swollen/blown elkos in power supply.
If two of them are 820 uF, just replace them with 1000 uF of corresponding voltage and all of those should be Low ESR type.
View attachment 168381

So:
I've changed some capacitors but with the same values. After that problem was not solve.

Hi,

a picture showing the electrolytic capacitors from the side would be useful, to see if their top's have lifted up.
But to me it looks they have not changed in "size" (from the provided picture), which is usually a clear indication of a faulty electrolytic capacitor.

BR

As I said before, capacitors don't looks like swollen, I've replaced three caps next to the trafo inverter (blue).

So acutally I solve the problem. I figured out, that when I will press the supply board after screen stop working then it works again, but when I release it stop working again. I figured out that on the blue trafo there are some cracks on the pin solders so I soldered it again. Everything works now. I don't know how long it will work, but now works. Next time I will replace this trafo inverter. What do you thing guys?

Thanks for your tips.

Regards,
Lukisek.

 

[BradtheRad]

Well done! You persevered and won.
The solder fractures around the transformer (often a bulky component) likely resulted from the monitor being struck or dropped.
I doubt the transformer is at fault. Anyway I'd be surprised if you can find an exact duplicate.

 

[Lukisek]

Thanks. I don't remember is there was a situation when monitor have been dropped. Maybe it can be this way: transformer is warm after about 10 minutes. Under the influence of heat, the tin oxidizes and a cold solder was formed, which turned into a cracks. Am I right?

Btw. I found duplicate in online shops with the same model signs.