Samsung PS51D550 51" Plasma - Issue? Any Help?

[Wabby]

Hi Guys,

I have a PS51D550 and it will not power on. I have performed some test but I am unsure as to the exact results of those tests.

Issue: When powered on, the front LED will flash 6 times, and then go off. Nothing comes on the screen.

Tests:
I have tested the following:

1) I have tested for Vs and Va and have neither when everything is connected up. If I disconnect the power to the X-SUS board (which is powered from the Y-SUS, not from the PSU directly) then I get the Vs and the Va, however they start dropping almost right away, the Vs right down to 8v, and then Va right down to 1v.

I have the correct power at VS_ON etc all the time.

If I disconnect the cable that goes from the Y-SUS to the MAIN LOGIC board, along with the power to the X-SUS, then I get solid Vs and Vs readings.

Under fully connected circumstances the LED on the MAIN LOGIC is flashing in the sequence of lit for 5 seconds, then 2 seconds off, then 5 back on etc.

I think that this means that the X-SUS is definitely faulty, but I am unsure as to whether the Y-SUS and/or Y-BUFFER are also possibly culprits?

I have experience in fixing LCD TV's, but not PLASMA so any help is appreciated.

Obviously don't want to be buying all the boards if they are not needed.

Cheers

[tom66]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

On these newer Samsung plasmas, pulling the power to the X- or Y-main boards will result in a brief Vs/Va then shutdown - this is fine.

You will probably find you have a shorted X-main - it is a common fault on the D450 series (720p) so would not surprise me if it also affected the D550s. You should check the transistors on the X-main board for short circuits.

[Wabby]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

On these newer Samsung plasmas, pulling the power to the X- or Y-main boards will result in a brief Vs/Va then shutdown - this is fine.

You will probably find you have a shorted X-main - it is a common fault on the D450 series (720p) so would not surprise me if it also affected the D550s. You should check the transistors on the X-main board for short circuits.

Cheers pal. Will test them this evening.

X-SUS are cheap enough to and easy enough to source for me to not even bother with component repair if any of them are shorted.

I had it down as the X-SUS only, so does that sound right? Probably no issue with the Y-SUS?

Cheers

[tom66]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

There is a small chance X-main failure has damaged the Y-main - you should check the Y-main for shorted transistors too. But if there are none you should be good to go.

[Wabby]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

Swapped out the X-Main and now sat watching the TV. Cheers for the input tom66

Now onto my next project - a 32 LED with ghosted vertical banding ...

[JRobinson]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

Hi everyone. I have only recently discovered this site and have read many forums relating to my current problem which I have found very helpful but now have a few questions of my own.

I recently purchased a second hand Samsung PS51D550 knowing that it wasn't working at the time. I have very limited experience (by very limited I mean practically none) in fixing electronics. When I first inspected the TV I looked at the capacitors which all look fine. Everything looked as it should as far as I can tell.

When I power up the set with all boards connected I get a clicking sound (two contactors engaging in quick succession then disengaging simultaneously) from the SMPS. This happens 5 times then stops. The red LED on the front panel double blinks 5 times then pauses briefly before repeating this pattern continuously. There is a green light on the logic board which flashes in sync with the clicking then remains off after the clicking stops. TV is nonresponsive to the remote, no sound is emitted and no picture is displayed.

When I unplug the X-main board from the Y-main board and the Logic Board I hear the two clicks from the contactors engaging. The green light on the Logic Board goes on for 5 seconds then off for 2 seconds and repeats this pattern continuously. Sound is emitted after about 35 seconds. Unit is responsive to remote but no picture is displayed.

When I unplug both the Y-main and X-main from all other boards I get very similar results as to when I had the Y-main connected and the X-main disconnected. Only differences being the green light on the Logic Board flashes on and off about every second and the sound only takes about 10 seconds to come on.

I have read that the REV numbers of boards should be the same across the boards. Do they all need to be the same or can you get away with some being different? SMPS REV1.3. Logic Board REV1.4. Y-main REV1.5. X-main REV1.2. Could this be causing the problem?

Looking forward to hearing your responses.
Thanks in advance,
Josh

[ehboy]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

good luck. i am dealing with similar problem, with a similar degree of background knowledge. thank goodness for the experts on here.

[tom66]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

It does sound like your X-main is bad, do you have a digital multimeter you could use to do some tests?

[JRobinson]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

Yeah I sure do. I've tried testing a few things but I don't really know what they all mean. What should I test?

[tom66]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

Try checking resistance across Vs and Ground on the X-main board. Remove the board from the set completely and use the 200 ohm range. Allow the reading to settle for 10 seconds before noting it.

[JRobinson]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

A I mentioned earlier, I have very minimal experience and have never been shown how to use a multimeter nor have any real education about electronics so I'm not sure if I have tested this right. These pictures explain what I have done better than my words could..
http://imgur.com/a/UWLGj

[JRobinson]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

Anyone out there who know what my problem might be? I don't know if my results from checking the resistance across the Vs and Ground on the X-Main were good or bad. Do I need to replace my X-Main board? And does it matter if the REV numbers don't match?

[saabman]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

I just recent fixed one for a guy at work - similar symptoms to what you are describing the X main board was shorting the VS supply. I was unale to obtain genuine RJP30H and GT30G124's the ones on ebay were fake and blew straight away.

I enede up replacing them with IRG7IA3 which fixed the problem (6 IGBTs in all)

[saabman]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

JRobinson your reading looks to be OK - I dont know what the actual value should be I no longer have access to he one I just fixed but 1.8K is not a short. If you flip the board over and check the resistance between each of the legs of the IGBt's if any of them are shorted your meter will display something like 0.00

I dont want to discourage you from having a go at fixing your tV but you will be fighting a loosing battle. The back of a plasma tV is not a good place to learn how to use a multimeter.

From what I have read the revision numbers do matter. Shopjimmy.com has some good information about reaidng board revision numbers.

[eytaneytan]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

I have the same issue (PS51D550), and I'm thinking of replacing the x-main board.

I see there are two version of this board:
http://www.aliexpress.com/item/Free-...451318400_6149

http://www.aliexpress.com/item/LJ41-...451318400_6149

A quick difference I spotted was one had 4 green capacitors on the side, and one has three and one empty spot. Is there a difference between these boards? and how should I know which one is right for my set?

[Jaitly]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

Hi i have the similar issue with my ps51d550. If everything is connected, i do not get any readings on va and vs. but if i disconnect x-main, i get the readings like 22.0 on vs and 04.4 on vs. please help me if there is a problem with x-main or psu. as i am new to these things, i have no knowledge.

[Nick's Tvs]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

Jrobinson
Try checking VS and VA lines to ground. Additionally as saabman suggested, check the legs of the transistors screwed into your heat sinks on your X main

Eytaeytan,
LJ92- is the part number of the board and the number you want to make sure you follow. These X-main boards have 2 different LJ92- numbers however one is for the 720P version and the other for the 1080P version of the board. How do you know which version is for you? Well there will be a thin bar code sticker on the board and on that sticker, the last 3 or so digits from one of the LJ92- numbers along with a suffix will be printed on that sticker. which ever last 3 digits matches will tell you which number to go with. 763A or 759A
http://www.shopjimmy.com/samsung-bn9...main-board.htm
If you click on the picture they will have that number I am talking about highlighted in marker on that sticker. Lastly either or will work on your tv, however if you use the wrong one, it will fail much sooner than it should and you will be back to square one fairly quickly.

Jaitly,
Same advice tom has been giving everyone else, unplug your tv and leave it unplugged for a while. Then grab a multimeter and check for shorts between ground and VS with all boards connected in circuit. If you get 500 ohms or less than disconnect the x-main and check it separately. To confirm the X or Y or both are your issue you can test the transistors that are screwed into the boards heat sinks. If for some reason you do not find a short on your sustains, you will have to jump your power supply boards PS-ON to ground and VS-ON to 5volt line. If you end up needing to do that then make sure all other boards are disconnected from it first. Once you do this you will be able to test the VS and VA voltages.
Good luck

[joeydfish]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

"I enede up replacing them with IRG7IA3 which fixed the problem (6 IGBTs in all)"

I concur this replacement part works, I replaced 2 RJP30H and 3 GT30G124 with IRG7IA3

Thanks!!

[Willem-Ben]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

"I enede up replacing them with IRG7IA3 which fixed the problem (6 IGBTs in all)"

I concur this replacement part works, I replaced 2 RJP30H and 3 GT30G124 with IRG7IA3

Thanks!!

Hi gentleman I have the exact same problem here in South Africa on the X main board and really appreciate your detailed brake down of this comman problem.

I however cannot find any IRG7IA3 on google or my supplier.

Please help if this is the correct number.

Thank you in advance.

[Willem-Ben]

Re: Samsung PS51D550 51" Plasma - Issue? Any Help?

Hi Gents I got the transistors and replaced them.So my X-main and y-main is good and checked all transistors,caps and resistors.

I don't have any shorts on the y-main or x-main even tested without the buffer board connected.

BUT:The only way I can get a healthy green LED flash is by removing the Y-main ribbon cable running to the logic board.

Voltages

That I get is perfect VA,VS,Vscan but VE is high should be 80 and i get 105 Vdc.

Im stumped on this one if somebody can help please.

Even if i don't connect the power from the PSu to Y-main and just connect the y-main ribbon cable don't have a healthy green led.

Sorry did not mention the unit X-main get the power from the Y-main.

Is there any other components that I could look at I dont want to buy a logic board as mention in other posts and sit with the same problem.

This unit is starring me in the face for last 2 months now and with your help we can surely beat this sucker.