Samsung PN43D450A2DXZA, won"t come on

[stratos976]

My Samsung decided it didn't want to come back on today. no picture, no sound.doesnt respond to touch button or remote. If power is cycled to it, several "clicks" are heard upon applying power and the standby LED blinks before remaining on contionusly.

I read through this site and others, and have tried to troubleshoot it. If I disconnect Ymain (and Xmain by default) I get the samsung melody and the touch button becomes responsive. If only the Xmain is disconnected from Ymain board, it goes back to the "clicks". With the Mains disconnected from the PS, I get 208v on the VS and 60v on VA, both go down slowly after power-up.

I also tested the pins on the Ymain and Xmain to ground, and the VS pins on the Xmain board show shorted to ground.

I guess its safe to assume the Xmain is bad?

with the Ymain effecting the PS even without the Xmain connected to it, could it be bad also?

Trying to figure out what boards to replace, I'd like to get some guidance on further testing, and others opinions on what the issue could be.

Thanks in advance,
Andy

[tom66]

Re: Samsung PN43D450A2DXZA, won"t come on

Huh, so you still get clicking with Y-main in, but you can't find any shorts on it? The X-main is a common fault on these models. The first thing to do is probably start checking all the transistors on the boards to see if they are OK. If you need help post pictures of the X- and Y-main boards.

[stratos976]

Re: Samsung PN43D450A2DXZA, won"t come on

I'll work on getting pictures posted. I checked the pins on the Ymain and none showed a short. And yes if the Ymain is connected to PS, wether the Xmain is connectedd to it or not it will still give the clicking

[tom66]

Re: Samsung PN43D450A2DXZA, won"t come on

When it does the clicking with Y-main in, do you get any Vs/Va voltages?

[stratos976]

Re: Samsung PN43D450A2DXZA, won"t come on

If I remember correctly, I dont think I did or they were very low < 1v. I checked alot of things and this being my first one, I'm sure I was troubleshooting in circles.

[tom66]

Re: Samsung PN43D450A2DXZA, won"t come on

Time to check for shorted transistors then..

[stratos976]

Re: Samsung PN43D450A2DXZA, won"t come on

Could there be other problems other than the Ymain and/or Xmain? from what I've read it seems like a good idea to change both plus the Ybuffer, if either is bad. I was thinking of going that route, but was curious if it could be a problem with another board.

[stratos976]

Re: Samsung PN43D450A2DXZA, won"t come on

Update: I ordered a y-main, y-buffer, and Xmain. Installed all three, but believe I may have a bad "new" (Refurb) xmain.

TV showed same symptoms when plugging it in, clicking and no picture, no voltage on vs/va.

I unplugged ymain from PS and would get chimes and correct voltage on vs,va

Plugged Ymain back in and unplugged Xmain, still had chimes and 207v on VS and 59v on VA. Bad Xmain or other issue?

[tom66]

Re: Samsung PN43D450A2DXZA, won"t come on

If Vs/Va are missing with X-main in, it's shorted, and faulty.

[stratos976]

Re: Samsung PN43D450A2DXZA, won"t come on

here are a few pics of the Xmain, if anyone could point out what to test on it.

Also could it be something in the TV that killed this "working" board immediately upon initial powerup? The Ymain and Ybuffer are new and as of now still appear ok.

[stratos976]

Re: Samsung PN43D450A2DXZA, won"t come on

i recieved a replacement X-main, is there a way I can double check this board (without a scope) to see if its ok before i install it.

I'm also 99% sure my new y-main and y-buffer are ok, is there anything else that could take this board out?

[stratos976]

Re: Samsung PN43D450A2DXZA, won"t come on

could the logic or power board kill it?

all of the 5.3v pins on my power board show continuity to ground around 47 ohms resistance... not 0 like lead to lead or ground pin to frame show.

I'm hesitant to put this X-main in, in fear I'll fry it

[tom66]

Re: Samsung PN43D450A2DXZA, won"t come on

Run the set without the X-main. Do you very briefly get a flash of light on the screen?

[stratos976]

Re: Samsung PN43D450A2DXZA, won"t come on

No flash of light, when applying power or when pressing the on switch.

[tom66]

Re: Samsung PN43D450A2DXZA, won"t come on

You can try checking for shorts.
For each marked device, check between all three combinations of pins, on the 2000 ohm range of your multimeter.
Report readings with the board Qxxx or Dxxx number near it.

[stratos976]

Re: Samsung PN43D450A2DXZA, won"t come on

On my known bad boards. the three devices at the top left are all shorted 1-3,1-2,2-3. Same with the three at the centerline of board. I tested board as it sits in pic and am counting pins left to right regardless of device position (pins on top or bottom). my meter has a 6k ohm setting

Readings on uninstalled X-main.
Q4002: 1-3: 5.4k, 1-2: OL., 2-3: 4.2k
D4010: 1-3: 0, 1-2: OL., 2-3: 4.2k
Q4007: all OL.
Q4001: 1-3: 6.5k, 1-2: OL., 2-3: OL.
Q4000: 1-3: 6.5k, 1-2: 5.2k, 2-3: OL.
Q4005: all OL.
Q4004: all OL.
D4004: 1-3: 0, 1-2: OL., 2-3: 4.1k
Q4006: 1-3: 5.7k, 1-2: OL., 2-3: 4.0K

[tom66]

Re: Samsung PN43D450A2DXZA, won"t come on

OK, you should repeat the test for the Y-main but if that is OK you should be good to put your X-main in.