Samsung ps51d6900 dk will not switch on

[Miller r5]

Hi I'm new to the site and looking for some advice.

My TV turned its self off yesterday, I was not in the room when it happened and will not turn back on. It was bought new in October 2011 and had a replacment screen fitted in January 2012.

If you switch it off at the wall and switch it back on the red light on the front flashes for 10sec or so then goes out. If you press the power button on the remote the red light wil light up then go out as soon as it's released.

It has no clicking noise and I have removed the rear cover and cannot see any damaged capacitors.

I have noticed it had a flashing green light under the panel and flashes ever 5-7sec, does this mean anything as it's referenced in this thread....

https://www.badcaps.net/forum/showthread.php?t=34121

Do you have any advice on this problem, does it sound like the power supply board?

Thanks for your help
Chris

[Miller r5]

Re: Samsung ps51d6900 dk will not switch on

A picture of the back of the TV

[tom66]

Re: Samsung ps51d6900 dk will not switch on

blink every 5-7 seconds indicates X-main or Y-main drive fault, do you have a digital multimeter available?

[Miller r5]

Re: Samsung ps51d6900 dk will not switch on

Yes and the rear panel is off.

[tom66]

Re: Samsung ps51d6900 dk will not switch on

OK try to locate the Vs test point on the power supply and take a measurement there. Red probe on the test point and black probe on a part of the metal chassis, reading should be in the range of 205~215V, DC.

[Miller r5]

Re: Samsung ps51d6900 dk will not switch on

OK try to locate the Vs test point on the power supply and take a measurement there. Red probe on the test point and black probe on a part of the metal chassis, reading should be in the range of 205~215V, DC.

Will it be called "vs-adj"

See pic

[tom66]

Re: Samsung ps51d6900 dk will not switch on

That's the one.

[Miller r5]

Re: Samsung ps51d6900 dk will not switch on

Ok switch on power at wall, placed red lead on vs adj then black on ground point and got 7v?

Thanks for you help tom it's much appricated

[tom66]

Re: Samsung ps51d6900 dk will not switch on

Can you take the measurement as the set is powered on? i.e. red lead on vs-adj and then power on TV. Note if it changes significantly, or if it is stuck around 7V.

[Miller r5]

Re: Samsung ps51d6900 dk will not switch on

It starts of at 210 then drops off very quickly to under 10v

[tom66]

Re: Samsung ps51d6900 dk will not switch on

OK, this indicates there is no short, so the next step, I will need a picture of the Y-main and Y-buffer. In your photo above, these are the large boards on the left hand side of the TV.

[Miller r5]

Re: Samsung ps51d6900 dk will not switch on

Are these ok?

[tom66]

Re: Samsung ps51d6900 dk will not switch on

There is a point marked VSCAN on the Y-main board, please test this. Should be about -187V according to panel sticker. The reading will be negative.

Could you get a clearer shot around the connectors where the buffer boards, bottom half, meet the Y-main board? I need to see the small traces.

[Miller r5]

Re: Samsung ps51d6900 dk will not switch on

Done the test as you described for the last one, it starts of at -187.2 then drops off quickly down to around -0.45 then goes open.

I will just get the pictures....

[Miller r5]

Re: Samsung ps51d6900 dk will not switch on

...

[Miller r5]

Re: Samsung ps51d6900 dk will not switch on

.....

[Miller r5]

Re: Samsung ps51d6900 dk will not switch on

And finally

[tom66]

Re: Samsung ps51d6900 dk will not switch on

OK, you see the points marked SVC_OUTL and SVC_OUTH on the buffer board? Measure the voltage between these points i.e. black on OUTL and red on OUTH.

[Miller r5]

Re: Samsung ps51d6900 dk will not switch on

With the power off i am getting 19.7ohms then when holding the probs on and powering up the TV it momentarily changes to volts but gives no reading (fluke automatic selection meter) and then changes back to show 21.8 ohms for 5 seconds or so then returns to 19.7ohms.

Cheers
Chris

[tom66]

Re: Samsung ps51d6900 dk will not switch on

Hmm, any way to lock your meter in volts or borrow a meter that can? That being said, 20 ohms between those points indicates a shorted buffer board to me, so I think that is the fault, but can't be sure because I've never used a meter that determines mode automatically (sounds confusing and bizarre personally.)