Hey all. Working my way through a diagnosis. Basically if the X Main Board is plugged in with power, the TV will not boot. No sound, just repeated relays clicking.

I noticed that Va does not get shorted to ground anywhere in the TV. On the SMPS and Y Main Board, Vs has high resistance to ground (20k ohms or higher). However on X Main Board, Vs has 0 ohms resistance to the chassis ground. Vs is shorted to ground ONLY on the X Main Board.

I have a second X Main Board purchased from eBay with the same behavior. Can anyone confirm whether this is correct?
...

Re: Samsung PN42C450 - Working my way through the diagnosis

Hey Tom66, what component(s) did you replace on that particular X-drive board? I'll pull that board out and look at it more closely.

Additionally: the troubleshooting manual below describes scenarios for certain failures...
Red tint: X drive failure
No picture: Y drive failure

Is this reliable? I have a (staticy) picture but only momentarily. Uploaded a lousy shot of the static....

Re: Samsung PN42C450 - Working my way through the diagnosis



I have a similar defect but not the same. My display turns on for about a second and shows static. I am unsure whether it's normal brightness.

I have no Vs/Va voltage when X-Main is not connected. Is it normal for the X-Main to "drive" the SMPS to provide Vs/Va?...

Re: Samsung PN42C450 - Working my way through the diagnosis

Randtek: Thanks, that was extremely helpful. I used it to find myself a new diagnosis...

What I know now:
-When all cables are plugged in EXCEPT for power to the X-Main-Drive, the TV powers on normally and even chimes and displays static for a second.
-Va/Vs voltages begin at typical values, however when the display turns off, the voltages return *slowly* back to zero.

I'd be inclined to conclude that my X-drive has failed. However, because the power is actually routed through...

Hi all,

Long time lurker, first time poster. My 42" Samsung plasma TV does not power on; instead a series of relay clicks are heard. I've formed my conclusion and want to bounce ideas off you guys. No bulged, discolored, smelly, or otherwise incorrect-looking caps or ICs anywhere.

What I know:
-After disconnecting all other boards to SMPS except the Logic Board, relays click twice and remain off. I can "force" the SMPS to go on my jumping PS_ON to GND.
-Doing this causes 5.4VDC and 15VDC in the correct places, but no voltage at Va/Vs...