Samsung LE40B652 - Not booting fully (incomplete melody)

[tom66]

TV will make a chime sound, but it cuts off part way through. The TV will boot up fully if the T-con is disconnected.

T-con: 2009FA7M4C4V0.9.

http://www.youtube.com/watch?v=7Xz-i...ature=youtu.be

Found out that an IC21, a MAX8727, has a dead short on the T-con board across its internal FET.

Now to replace it. Or replace the whole T-con (but that's around £50 so I'd like to avoid it.)

My first Smart TV. Now to get an LED TV.

[tom66]

Re: Samsung LE40B652 - Not booting fully (incomplete melody)

Frustrating. Knocked a resistor off the board while changing one IC. And it's gone... with no clue of the value. Found new T-con at £40, fairly steep but it should fix it (most were at £50 this was just added.)

[kevinm34232]

Re: Samsung LE40B652 - Not booting fully (incomplete melody)

Nice job diagnosing that. Can you explain more on the diagnosing process you used, you said you scoped the 13v line and then used a power supply.. I would love to see those parts in the video. The freezing technique was cool too...

[tom66]

Re: Samsung LE40B652 - Not booting fully (incomplete melody)

I didn't get a video of those unfortunately due to low memory on the camera. But I've used my scope on previous videos so the method shouldn't be difficult to figure out.

[budm]

Re: Samsung LE40B652 - Not booting fully (incomplete melody)

One thing that help troubleshooting is the spec sheet of the IC, most of the time it will show what are inside the IC, in this case, Tom was able to check the internal MOSFET of the IC.

[tom66]

Re: Samsung LE40B652 - Not booting fully (incomplete melody)

Finding out it was a MAX8727 helped a lot...

[tom66]

Re: Samsung LE40B652 - Not booting fully (incomplete melody)

Good news is the TV is now showing a picture. Bad news is the T-con is defective because there's a green haze over the whole image which follows moving objects and is visible with LVDS setting changed to make colours different. Most likely this is due to the motion compensation (100Hz etc.) Upon looking at the T-con we had spent forty of our British pounds on, we found it to have flux around the SEMP74 (motion) processor and the motion processor's RAM. Clearly, someone had tried to reflow this board, and likely failed. Perhaps they smashed the screen in frustration and that's why it appeared on eBay. We're sending it back and buying one for £44. Annoying, but we're nearly there.

[tom66]

Re: Samsung LE40B652 - Not booting fully (incomplete melody)

New "new" T-con fixed the TV, yay.

[budm]

Re: Samsung LE40B652 - Not booting fully (incomplete melody)

Great job Tom. Did you get the money back on the bad replacement board? Did you still have to pay for shipping it back?

[tom66]

Re: Samsung LE40B652 - Not booting fully (incomplete melody)

Yes, we just told them we knew it had a reflow job done on it, and a bad one at that, and they refunded it, but told us to keep the old board. So we now have a partially functional spare board for doing tests on.

Funny, I had a similar green haze fault on an LE40A656, but it only affected every second 4" or so of the display. That too was the T-con -- probably the motion interpolation IC on that one as it did also appear affected by motion.