Samsung PN51D550 Clicking and blinking led

[Diyer]

Hello, I have a Samsung PN51D550C1FXZA which has a start up clicking issue. The red LED up front will blink twice 5x then nothing. I've tested some components on the boards and my findings are below. Any help that can lead me fixing this issue via replacing components or boards would be greatly appreciated.

All boards connected. (tv clicks and led blinks)
No PS-Vs, PS-Va, Y-Vs, X-Vs, VSCAN or Ve reading

All boards connected but all ribbons removed from the main board. (tv clicks and led blinks)
No PS-Vs, PS-Va, Y-Vs, X-Vs, VSCAN or Ve reading

All boards disconnected from the PS. (no click and no led)
No PS-Vs, PS-Va, Y-Vs, X-Vs, VSCAN or Ve reading

Only logic and main board plugs removed. (no click and no led)
No PS-Vs, PS-Va, Y-Vs, X-Vs, VSCAN or Ve reading

Only Y-main plug removed from PS but ribbons connected
PS-Vs goes from 207 to 0, PS-Va goes from 58 to 0, Y-Vs=0, X-Vs=0, VSCAN=0 Ve=0

Only X-main plug removed from Y-main board but ribbons connected (tv clicks once)
PS-Vs goes from 207 to 0, PS-Va goes from 58 to 0, Y-Vs=207 to 0, X-Vs=0, VSCAN=goes -187 to 0 Ve=0

Only X-main plug removed from Y-main and X-main ribbon removed from main
PS-Vs 11v, PS-Va goes from 58 to 0, Y-Vs=11v, X-Vs=0, VSCAN=goes -187 to 0 Ve=0

All Y & X main plugs and ribbons removed
PS-Vs=239v, PS-Va=58,Y-Vs=0, X-Vs=0, VSCAN=0 Ve=0

Only Y-main ribbon with X-main plug and ribbon removed. (y-main plug still connected)
PS-Vs=207v, PS-Va=58,Y-Vs=207v, X-Vs=0, VSCAN=-187v Ve=35.0mv



Any suggestions on whats going on and how to fix it would be greatly appreciated.


Thanks in advance
Sam from Michigan

[Diyer]

Re: Samsung PN51D550 Clicking and blinking led

I'm confused why when the Y-main is plugged in but the x-main cable and ribbons are removed I have no voltage till I also remove the Y-main ribbon. Can I conclude that the x-main is bad?

[tom66]

Re: Samsung PN51D550 Clicking and blinking led

Could you include a picture of the parts in the TV so we can see how it is laid out?

[Diyer]

Re: Samsung PN51D550 Clicking and blinking led

Vola!

[tom66]

Re: Samsung PN51D550 Clicking and blinking led

To me, it looks like a Y-main fault.

Samsung plasmas shut down Vs/Va after a few seconds if X- or Y-main activity is not detected. You have very low Vs without Y-main, but you do get brief Vs with it out.

It is possible both X- and Y-main are bad, so try checking the transistors for shorts too.

[martino]

Re: Samsung PN51D550 Clicking and blinking led

On bufferboard(far left narrow board) just above the top white connector you find two test points,SVC_OUTH and SVC_OUTL.
CAn you measure resistance between those two with ohm meter?
If bufferboard is shorted,you will measure around 24ohms.....

[Diyer]

Re: Samsung PN51D550 Clicking and blinking led

Hi Tom66,
Can I check the transistors while they are on circuit or do I have to remove them to get a true reading?

Martino with the only the y-main attached to the power supply I get a 0-ohms but with everything connected like normal I see its ranging from 600k - 7M Ohms.

[martino]

Re: Samsung PN51D550 Clicking and blinking led

This SVC checking should be done by disconnecting the yboard from the bufferboard,its purely to test if the bufferboard is shorted out.
SVC_OUTH<<-----OHM----->>SVC_OUTL

[martino]

Re: Samsung PN51D550 Clicking and blinking led

See pic for sample,this one is shorted out as you can see from the ohm reading....sry about the dark pic...

[tom66]

Re: Samsung PN51D550 Clicking and blinking led

Any value than a few 100kohm is bad across those points.

[Diyer]

Re: Samsung PN51D550 Clicking and blinking led

Hey guys,

I removed the y-bufferboard and tested the resistance between the points. 150kOhms so I guess that rules out the y-buffer being bad. Can you tell me if I have to remove transistors from being in circuit to test them or can I do it while in circuit.

[tom66]

Re: Samsung PN51D550 Clicking and blinking led

You can test them in circuit.

[martino]

Re: Samsung PN51D550 Clicking and blinking led

I have the exact same TV here,Fixed it for a friend,he hasen't picked it up yet,I was lucky enough to have 3 of the same TV's sitting here for parts,so plenty of boards for it
If you guy's want some measurements from certain areas etc,let me know and I will gladly assist in doing so.

[Diyer]

Re: Samsung PN51D550 Clicking and blinking led

Ok so I removed the y-main board and removed 2 of the transistors on the board for testing upon removal I found that I can only get a reading from touching my negative lead to the collector and the positive lead to the emitter everything else gave me an O.F reading. Based on what I've read online I'm guessing this means I have a bad transistor (Fairchild - FGPF4536)?

[Diyer]

Re: Samsung PN51D550 Clicking and blinking led

Ok so I woke up this morning and did some more research on how to test an IGBT transistor and found out that my transistors are OK. Any suggestions on what to test next.

Thanks

[tom66]

Re: Samsung PN51D550 Clicking and blinking led

Test all the transistors you can see. You don't need to remove them for checking for short circuits. Simply test across all three pins (1-2, 2-3 and 3-1)

[Diyer]

Re: Samsung PN51D550 Clicking and blinking led

Tom66 what setting should I have my DMM on and what values I'm I looking for?

[tom66]

Re: Samsung PN51D550 Clicking and blinking led

200 ohms. Any reading lower than a few ohms is suspect.

[Diyer]

Re: Samsung PN51D550 Clicking and blinking led

Ok so everything seems to check out on the y-main board. So I took out the X-main and test the transistors and found a couple giving me a short reading and <20ohms. So I desoldered the transistor and it still tested short on all legs and <20ohms. Its a RJP30H1 transistor and I've also noticed all the transistors on the same side of the board are testing the same way in circuit (short and low ohms). Please refer to the pic the transistors with a red mark are testing short in circuit and low ohms. The yellow transistors are model #AUK-61825-SF10A400H Purple# 30G124 Orange# AUK-91811-SMK1820 Green# RJP30H1.

[Rubiks06]

Re: Samsung PN51D550 Clicking and blinking led

I have the same problem. I've replaced x-main and y main. I'm showing 2kohm across y buffer. Help?