Samsung Plasma PN50C550G1F : no image, but sound is ok

[superbigjay]

Re: Samsung Plasma PN50C550G1F : no image, but sound is ok

The X board seems to receive its power from a cable connected to the Y-sustain board...

[superbigjay]

Re: Samsung Plasma PN50C550G1F : no image, but sound is ok

To disconnect the X and Y boards, I only have to disconnect the power cable from the PSU to the Y-sustain board?

There no power cable that seems to go from PSU to X-board...

[superbigjay]

Re: Samsung Plasma PN50C550G1F : no image, but sound is ok

I'll test the voltage with a 1K Ohm load on it.
Can I use any 1K resistor (I have a bunch of small resistors here, but not sure if I need "bigger ones" that support at least X watts)?

Here's a pic of the power supply (BN44-00330A).

[MagicSmoke]

Re: Samsung Plasma PN50C550G1F : no image, but sound is ok

Need pics of PSU. Most newer Samsungs have protection circuits to shut down VA & VS when there is a fault on X ,Y or PSU.

You can disconnect the cables that power the X & Y boards and force PSU on with a 1k ohm resistor to see if VA & VS volts are present and stable.

[superbigjay]

Re: Samsung Plasma PN50C550G1F : no image, but sound is ok

https://www.badcaps.net/forum/showthread.php?t=18542

thanks sordids999,
that thread mention taht the most probable cause is the y-sustain.
But since the Vs voltage wasn't stable at its 200+VDC, I am not sure if it is the y-sustain, or the power supply.

It also says that the no picture is a bit more complicated to troubleshoot and suggest to create a new thread for it (post #4).

I have not read in other post a similiar problem (VS startting at about 200VDC, but decreasing rapidly).

Anyways, I'll conitnue reading the proposed thread... I'm at page 3 of 19.

Jay

[sordids999]

Re: Samsung Plasma PN50C550G1F : no image, but sound is ok

https://www.badcaps.net/forum/showthread.php?t=18542

[superbigjay]

Hello,

I've got my 50in plasma that just gave up on me : no image, but sound is working.

From what i have read, the cause is usually one of these three boards:

- power supply
- y sustain
- y buffer

I have done a visual check for blows caps and couldn't find any defective caps.
I have check th AC fuse and it is fine.

The 110VAC line is fine.
The Va and Vs lines behave strangely:

Right after power on, the DV voltage is near their nominal DC voltage (about 200VDC and 50VDC, but decrease until they reach 0V in about 20 seconds).

(This is with all boards connected).

Anyone have seen such behavior and could help troubleshoot the problematic board ...

I don't mind replacing 1 board if it has a good chance of fixing the problem, but I don't want to end up replacing 3+ boards and spending almost 50% of the tv price tryinng to fixing it.

Any ideas/tests/measurement that could help identify the culprit.

Jay