Samsung 245B 00173A No power No blue LED

[budm]

Re: Samsung 245B 00173A No power No blue LED

T-CON board is under the metal shield:
https://www.badcaps.net/forum/showth...t=samsung+245b

[momaka]

Re: Samsung 245B 00173A No power No blue LED

T-CON board is under the metal shield:
https://www.badcaps.net/forum/showth...t=samsung+245b

Right you are, budm. No wonder I couldn't find the T-con -associated circuitry on the pictures that redoxy just posted. So it looks like this monitor has the T-con board separated from the thin LCD panel board that is attached to the TFT (this is more typical for LCD TVs than monitors). So yeah... all the parts we need to check are going to be on that board that budm mentioned. It appears from the pictures of the thin long board that you posted that only perhaps the gamma chips are on it.
Will wait for more pictures.

[redoxy]

Re: Samsung 245B 00173A No power No blue LED

Where are the pictures of the whole back side of the monitor showing all the boards I requested?

Sorry for the late reply. I was away.

Here is the picture of the back with all the boards.

[momaka]

Re: Samsung 245B 00173A No power No blue LED

Thanks.

Using this board as a reference...
https://www.badcaps.net/forum/attach...6&d=1538851538
... first check fuse F1 (should show good continuity). Next, check the voltage on test points 5VDD, 3VDD_A, 3VDD_B, AVDD, VON, and VOFF. Post what voltages you get here.

5VDD should be about 5V. It's what supplies power to the entire t-con and TFT-attached panel boards
3VDD_A and 3VDD_B appear to be linearly-regulated from 3.3V regulators, so you should get about 3.3V on each.
AVDD is the main boosted rain - typically around 10-18V (varies with monitors and TVs)
VON is one of the two secondary boosted voltage rails and typically around 12-30V. Often also goes by the name of VGH on some monitors.
VOFF is the other of the two secondary boosted voltage rails and typically around -5 to -10V (negative voltage relative to ground). Often goes by the name of VGL on some monitors.

Let us know what you find. Be careful when powering up the monitor to check these rails and make sure the boards are well insulated beneath and not shorting on anything metal.

[redoxy]

Re: Samsung 245B 00173A No power No blue LED

Thanks.

Using this board as a reference...
https://www.badcaps.net/forum/attach...6&d=1538851538
... first check fuse F1 (should show good continuity). Next, check the voltage on test points 5VDD, 3VDD_A, 3VDD_B, AVDD, VON, and VOFF. Post what voltages you get here.

here are the results. There is continuity in the fuse F1. I tested with power on and the screen on.

5VDD = 5.22 Vdc
3VDD_A = 3.29 Vdc
3VDD_B = 3.28 Vdc
AVDD = 11.93 Vdc
VON = 14.6 Vdc
VOFF = -5.61 Vdc (when I reverse the leads with the positive red lead on ground and the ground lead on the VOFF it reads 5.61).

I tried the working monitor's T-con board on the non-working monitor and it was still the same. power on with white screen.

I guess this means end of the road for the LCD panel.

[momaka]

Re: Samsung 245B 00173A No power No blue LED

I guess this means end of the road for the LCD panel.

Not quite yet.
What happens if you put all of the boards from the good screen onto the bad one? If it works, then issue could be back on the logic board then. Typically white screen is t-con board, but not always, as this seems to be the case here now.

From the voltage you posted above, VON does seem a little low relative to AVDD - it's like it's almost not boosting at all. But since you tried the t-con from the working monitor, that rules out the t-con.

In that case, go back to the TFT panel board and look for shorted ceramic caps. Anything under 30-Ohms on a ceramic cap I'd say is suspicious (and even under 100 Ohms could be an iffy cap somewhere). Or it could be the gamma ICs.

But before digging in any deeper with the TFT panel board, first try the working boards from the working monitor (power supply, logic board, and t-con). If monitor still shows white screen, then check the TFT panel board out.

[redoxy]

Re: Samsung 245B 00173A No power No blue LED

Thanks momaka.

when i transfer all the boards from the good screen i still get the same white screen when monitor is powered on.
So now the only board left will be the the long tft panel board.
As i mentioned earlier, i'm a complete novice when it comes to circuit boards. And looking at the tft panel board even if i identify the bad component, i do not think i will be able to properly replace it to fix it. So i will throw in the towel here and see if a can either find a reasonably priced tft panel or use the boards as spare for the working screen in case any of the boards need replacing in the future.

Thanks all for the guidance and input. if nothing at all i learned a lot and i have a spare working board due to the knowledgeable folks on this forum.

Cheers!!