Samsung PN43D450A2D No Video

[tom66]

Re: Samsung PN43D450A2D No Video

You will need to unplug the X-main board, take it out, and we can show you how to test for shorts. It is sometimes advisable to swap or repair both X-main and Y-main.

[phantom715]

Re: Samsung PN43D450A2D No Video

X-Main Front:


X-Main Back:


Thank you so much.

[tom66]

Re: Samsung PN43D450A2D No Video

I've highlighted some places to make tests.

On each of the devices I have highlighted note the part code e.g. D8280 or Q8099 and the resistance (200 ohm scale) measured between pins 1-2, 2-3 and 1-3. Note numbering is arbitrary (i.e. as you wish), but between each device try to be consistent.

[phantom715]

Re: Samsung PN43D450A2D No Video

The attached PDF table is slightly easier to read.

Code 1-2 2-3 1-3
------ ----- ----- -----
Q4000 Open Open Open
Q4001 Open 190* Open
D4008 150* NA NA
Q4006 150* Open Open
D4004 Open 150* .2**
Q4007 Open 170* Open
Q4004 Open 140* Open
D4010 open 140* .2
Q4005 Open 150* Open
Q4003# Open Open Open
Q4002 Open Open 170*

*Value is averaged; value is measured, & disappears – is instantaneous and does not hold steady.
**Solder connects the two pins across the board – see picture.
#Picture is attached – does not appear to be connected properly – is missing the outer 2 posts connecting to the board like all the other components.

Thank you again.

[tom66]

Re: Samsung PN43D450A2D No Video

Looks like there are no shorts. That FET with the missing leads is very strange. I have seen later versions of that board with that FET completely missing. Chopping the leads would do the same thing as not putting it on at all, so it's probably a modification done after the fact. Wonder why they did that...

Next step is to look at the Y-main. You can test similar devices on it.

[phantom715]

Re: Samsung PN43D450A2D No Video

Sorry - I've been out of town for a while. Here's the Y Main components that I've tested.

[tom66]

Re: Samsung PN43D450A2D No Video

"O" = Open or Zero?

[phantom715]

Re: Samsung PN43D450A2D No Video

Sorry; meant to edit that before I sent it. Those mean Open.

[tom66]

Re: Samsung PN43D450A2D No Video

Q5013 is the only suspicious device then. Can you get a picture of it and the surrounding area?

[capkid]

Re: Samsung PN43D450A2D No Video

Here are my thoughts: https://www.badcaps.net/forum/showpo...74&postcount=5. I just repaired this model a couple weeks ago. The X-main was bad in my TV, but I blew the Y-main during testing. I won't make that mistake again.

The gist of what I say in that post is that it appears that a surface mount component blows, damaging one or more of the through-hole components on the heat sink on the same circuit. To me, connecting the Y-main or X-main to the power supply to verify whether the VS or VA stay up is asking for trouble on these TVs.

[phantom715]

Re: Samsung PN43D450A2D No Video

Q5013 is the only suspicious device then. Can you get a picture of it and the surrounding area?

Attached are the pictures; one of the front, one of the back. Q5013 should be in the center of the pictures.

[phantom715]

Re: Samsung PN43D450A2D No Video

*bump*

[Clydeuk]

Re: Samsung PN43D450A2D No Video

Samsung issued a revised X main for this problem, I would say it is a very likely culprit we had hundreds of these in still under 1st year warranty. It does normally short when it fails.

[tom66]

Re: Samsung PN43D450A2D No Video

Sorry I did not notice your post, but that FET doesn't look to have anything in parallel so it is suspect.
I have replaced X-main boards in three Samsung plasmas, they just don't last.

[Clydeuk]

Re: Samsung PN43D450A2D No Video

Watch out for the blue capacitors on these as well, they tend to burn, maybe the original cause of the failure.

When we first started seeing these, sometimes brand new failures out of the box, samsung supplied the whole PDP to replace. Later they started supplying the X Main and CTRL as a kit for repair. The CTRL was advised to replace as they changed the ROM version, though I don't recall having to swap out many. The new X Main had slightly different coils on it's output side.

[hienton2]

Re: Samsung PN43D450A2D No Video

I fixed one board like that last week(LJ41-09478A X main). Q4002,4003,4004,4005. RJP30H1 shorted

[phantom715]

Re: Samsung PN43D450A2D No Video

So, since I'm kind of new to this, would it be easier to replace certain components, or try to get a new X-Main board from Samsung?
Thank you all!

[hienton2]

Re: Samsung PN43D450A2D No Video

Better get a new board. It is hard to have fets.

[phantom715]

Re: Samsung PN43D450A2D No Video

Sorry I did not notice your post, but that FET doesn't look to have anything in parallel so it is suspect.
I have replaced X-main boards in three Samsung plasmas, they just don't last.

THANK YOU! I was able to order a Y-Main board from EBay for $21, and it worked. Thanks for all your help!

[tom66]

Re: Samsung PN43D450A2D No Video

Glad it's fixed. Apply the update to the firmware to avoid a second replacement!!