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Samsung TV power LED flashing pattern as soon as plugged in

TV was stored in attic for the past 6 months probably subjected to hot summer and cold winter. Pulled it out and plugged it in and it worked fine for about 3 hours. While i was searching for the Roku remote. That is when i noticed that the TV had shut off and was flashing. I figured it was some kind of sleep mode but well i was never able to wake it.

Details: LN26B360C5DXZA

As soon as power is plugged in the red power led starts flashing a repeating pattern.

On for 1 second, off for 1 second, on for 2 seconds, off for 2 seconds.

Things I have tried:

Unplugged and set for 24 hours. Still flashing pattern immediately after plugging in.

Checked the glass fuses on the power board - two total, not blown

Checked the output voltages of the power supply board - All present at the correct level

Checked all the Electrolytic Caps - none are bulging, ESR is low and the few that looked questionable I removed and verified capacity was still correct.

Reseated all connectors

Checked voltage regulators on the video board - 7805 and 7809 had a 5 and 9 volt output respectively.

Reflowed solder joints on power supply board with hot air rework station/soldering iron

At this point I am out of ideas and am hoping someone with more TV or Samsung troubleshooting knowledge can point me in the right direction so i don’t have to give up on this and toss the TV.

Thanks in advance

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Voltage measurements after reflowing ( described in my comment below )

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Okay, so I reflowed the video board in the oven last night, 15 minutes at 320F. No difference. I was cautious with the temp because of the plastic connectors but I wasn’t convinced that the solder had actually liquefied.

I put the board the oven again for 10 minutes at 320F then removed carefully and put both BGA chips under my hot air reflow gun. After 30 seconds I could see the solder liquid on the main square BGA.

I switched my focus to the to the smaller adjacent rectangular BGA chip. After a few minutes of hot air and slowly cranking the temp up to 600F it still felt rigid to the PCB. I am not sure what to think about this component, but I stopped applying heat at this point.

After all this work still no difference. The power LED flashes the pattern immediately when plugged in.

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Being stumped, I got my meter out again and started testing some additional voltage regulators on the video board that I had just identified when I started to notice the DC voltages are lower than before. Lower than I would like to see.

Unfortunately I was not able to look into this further last night as it was fairly late and you know, work in the morning… But I’m now thinking it’s a power issue again. I will poke around more tonight.

See image below depicting the voltages I measured and where. Advice always welcome. Thanks.

[image|1757103]

Edit: Can't add images to comments... See main post for image...

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1 solution

Reflow the BGA. I tried this on a similar model. Put it in the oven for 15 minutes and reflow that main board.

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jack baker sera éternellement reconnaissant.
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