Samsung PN43D450A2D

[tom66]

Re: Samsung PN43D450A2D

Great, this rules your PSU out, but it gets tricky now, as the fault is on the main or T-con.

I can't see a danger with plugging them in, but I don't think the set will power on. Worth a shot I suppose.

I've highlighted several components.

Do all measurements with the resistor removed and TV plugged in.

For each red device (voltage regulator / LDO):
- Note down voltage on each pin relative to case of TV
- Note down part # (e.g. KIA 78M08, or LD1117-18, ...)

For the green test point:
- Report the voltage on the nearby black diode's pin relative to case.

For the blue test point:
- Report the voltage on the nearby brown cap pins relative to case. (You need only test one, just make sure it's connected to that visible trace coming out of the "4R7" component.)

[crashp3]

Re: Samsung PN43D450A2D

Thanks again! I uploaded a new picture and labeled each device. RED devices are numbered 1-6 and their results are below. I've also drawn arrows to the main components next to the Green and Blue test point if it helps.

For components 2, 3, 5, 6, the first line identification is "C-11" in my notes below, however on the chip it looks like a backwards C, or a D without the straight line.


1:
Left - 0v
Right - 0v
KIA
7805AF
051

2:
L: .09v
R: 0v
C-11
1117z
1102DG

3:
Top: .6v
Bottom: 4.6v
C-11
1117Z
1102DG

4:
Top: .6v
Bottom: 4.6v
78M09A
0R5E

5:
Top: .007
Bottom: 0
C - 11
17-33Z
1040CG


6:
L: .007
R:0v
C - 11
17-33Z
1040CG

Blue:
1.1v

Green:
4.63v

[tom66]

Re: Samsung PN43D450A2D

Sorry, communication error on my part. You need to test the tab pin (top) on each regulator as well. The tab pin is often the output voltage.

Your blue test point looks okay for a 1.1V core voltage for the main processor, though I'm not certain.

[crashp3]

Re: Samsung PN43D450A2D

No no my fault - I should have known that

Here is the test tab on each regulator, same numbering convention as before:

1:
0

2:
0

3:
1.85

4:
0

5:
.53

6:
.08

[tom66]

Re: Samsung PN43D450A2D

OK, the only suspect at the moment is #4, as its output should be 9V, but it is 4.6V. But I notice the input voltage is only 0.6V, so this is likely the cause. But it is a bit strange.

The regulator giving 1.85V is fine. The output should be 1.25V(ref voltage) + 0.6V(ADJ voltage) = 1.85V.

Also... Try unplugging the speaker connection; a user on this forum reported this let his TV power up because a shorted speaker was causing problems.

Also, are there any components on the bottom side of the main board?

[crashp3]

Re: Samsung PN43D450A2D

Just tried with the speaker unplugged - no change. Doesn't appear to have any components on the bottom side of the board.

Here's a shot.

[tom66]

Re: Samsung PN43D450A2D

My suggestion would be to replace the main board... Other than that, I cannot be certain of the failure, but it certainly looks like a main board issue.

[crashp3]

Re: Samsung PN43D450A2D

Thank you for all of your assistance today, tom! I'll get a new one ordered up and post back with the results!

Out of curiosity, would replacing #4 possibly make a difference, or does the input voltage being wrong throw out that idea?

[crashp3]

Re: Samsung PN43D450A2D

Just to update any future readers - per the advice of tom66, I replaced the mainboard and this corrected the problem!

Thanks again Tom for saving my TV from the dump!

[killingscum]

Re: Samsung PN43D450A2D

Hello everyone sorry I'm bringing up an old issue but I am having a similar problem as well and I though rather then starting a new thread I would just build on this one. I will try to be as descriptive as possible on what happened and what is going on.

I was watching TV (same exact modle TV as the topic) when all of a sudden the screen went black and started making a clicking noise which sounds like its trying to turn on and off--after unplugging the TV and plugging it back in again all it did was click.

So far I have inspected all the boards and cannot see any bad capacitors or obvious signs of failure. I have since replaced the power board and the mainboard (which my original one actually had heavy contamination but is still working) but am still having the same issue.

I am a n00b at TV repair so forgive me if I do not know the name of some components in the plasma tv.

Now I have noticed if I leave everything plugged in it makes the click on/off sound, but if I disconnect the board I am calling the X board (the one without the processors attached) the TV turns on, it makes the start up sound and you can even see the light flash when putting the volume up-- I even saw 3 white horizontal lines come on the screen for a split second at one point.

I believe it may be that x board that has failed but seeking some guidance.
Thanks in advance for any help

[mbarnard]

Re: Samsung PN43D450A2D

Im with the guy above. Unplugged his picture of the "X" board and i have sound can change channels and all that but no video is there something on that board i could replace?

[tom66]

Re: Samsung PN43D450A2D

Replace the X-Main. It's available for around £10~15 in the UK. I don't bother to repair these as the cost of the transistors on them which fail outweighs the cost of a new board.

[dtg616]

Re: Samsung PN43D450A2D

Hey guys, I'm running into the same exact problem with my PN43D450A2D... I've replaced the x, y and logic main boards with no change.

Basically what happens is with everything connected, I plug the tv in and the little black box on the bottom of the psu clicks, then clicks more when I try to turn it on and then just eventually quits and the tv doesn't do anything.

If I unplug the y or x board, the tv will click once and then I press the power button and am greeted with the samsung power on music. I can turn it off and on with no issues, but have no picture.

I've inspected the psu and the board with the hdmi/cable connectors and don't notice anything blown. I do see a red light emitting from what I'm assuming is the optical port too.

Any ideas here? I'm getting kind of sad buying parts and not having it fix this thing.

If you need any pictures, let me know.

[tom66]

Re: Samsung PN43D450A2D

We are seeing quite a lot of boards defective from ebay sellers etc who never test them. If your TV clicks with the Y-main plugged in (given they are chained) the Y-main is defective.

Other things to take care about are the fact that a bad Y-main can damage the X-main and vice versa, so if you've only swapped one at a time it would be advisable instead to swap both.

[dtg616]

Re: Samsung PN43D450A2D

It's fine with the y main connected.

Once i pull the x mains power, everything seems to power up correctly, short of the picture.

[tom66]

Re: Samsung PN43D450A2D

In which case the X-main is probably bad, but a Y-main that is not directly shorted could still damage the X-main.

[dtg616]

Re: Samsung PN43D450A2D

If there was a power surge on the unit, could that cause all the problems via the power supply board?

[tom66]

Re: Samsung PN43D450A2D

Unlikely. These Samsungs are poorly made and die on their own terms.

[dtg616]

Re: Samsung PN43D450A2D

Sounds like this is a craigslist buy / fix it yourself ad kinda thing then.

Thanks for the help.

[datadummii24]

Re: Samsung PN43D450A2D

hey tom,

im having the same issues as crashp3. however, when i plug in the power source the clicking does seem to originate from the transistor you highlighted in your first response. any suggestions before i start reading voltages with dmm