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Samsung LN46A550 Won't Turn On

post #1 of 8
Thread Starter 
I have a Samsung LN46A550P3 which is just out of warranty. I had been very happy with this TV until last night when the screen displayed static/snow for a couple of seconds, accompanied by a loud static/snow noise, then it shut down.

The Blue light under the screen is illuminated, the standby light is blinking, and there is a solenoid type clicking at regular intervals from the rear of the TV. Sounds like it might be the power supply tripping. The power brick I was using has the grounding light illuminated.

I have tried disconnecting all devices such as PS3, HD DVR, etc. Have unplugged the power cord, tried a different wall socket, and left the TV unplugged overnight, but the same condition existed this morning.

From some research it looks like it could be either the internal PSU, or the rear input board which is the cause.

Any help in troubleshooting/determining cause will be greatly appreciated before I go to the extent of taking it to a service center. If I can repair it myself, I will do so.
post #2 of 8
Check the link. It sounds like the bad capacitors on the power board. Instructions at the link on how to fix:

post #3 of 8
Thread Starter 
Thanks for the info!

As it happens I had a stroke of luck. I called Samsung on the off chance I could get them to help. Warranty ran out on 9th January, but when I called they told me my warranty was valid until 9th April. I completely forgot I got an additional 3 months warranty from Samsung when I bought the TV for registering online. My online profile didn't show it. Anyway, with 9 days left of my warranty, they have opened a ticket for me, and I'll get it repaired gratis!
post #4 of 8
Good to hear.
post #5 of 8
Good to hear someone being on the "right" side of the warranty expiration.
post #6 of 8
Thread Starter 
They just got done repairing my TV. Took 20 minutes. New motherboard, and it's back up and running!
post #7 of 8
If you replaced the capacitors on the power supply and still have a clicking TV, this post is for you.

My Samsung LN46A550P3FXZA had the clicking problem with flashing red LED on the front panel. Replacing the power supply capacitors didn't bring the TV back to life. I found a voltage regulator integrated circuit on the main board had died.

This repair is for those with a high degree of skill at soldering. I won't go into details other than to point you at a "do it yourself surface mount soldering with a heat gun" video, point you at the parts to change, and tell you what those parts are and where you can get them. If you're not quite skilled in soldering, I urge you to find someone who is to do this work. You really can destroy your board this way and I'd rather you fix the TV than utterly trash it.

What you'll need:
  1. DC voltmeter.
  2. Soldering iron, fine gauge solder.
  3. Heat gun, solder paste.
  4. Tweezers.

  1. Plug in your TV and measure the voltage at the solder pad on the main board pointed to by arrow #1 in the pictures below. This is the thin sliver of a pad sitting between the inductor and the shield can. Be very careful not to short your test lead to the shield can in this process -- wrap your test lead tip with a piece of stiff wire from a resistor lead to make a skinny probe if need be. You should measure 1.1VDC when the TV tries to switch on. If it doesn't, then your culprit is the same as it was in my TV, so carry on with the steps in this list to correct the problem.
  2. From www.mouser.com, order quantity two voltage regulator integrated circuit number MP2363DN-LF and quantity two Shottky diode number CD214A-B240LF. I recommend two since they're cheap and you'll have a spare in case you break one during installation.
  3. Note that you can also get top quality, ultra long life replacement power supply capacitors from Mouser. For this set, you'll need quantity two UHE1E821MPD, two UHE1V471MPD, and two UHE1C102MPD. You can find instructions for replacing them on other posts.
  4. Unplug, unscrew, and remove the main board.
  5. Remove and replace the diode pointed to by arrow #2 with one of the CD214A-B240LF diodes you bought from Mouser.
  6. Watch this video about replacing a surface mount part with a heat gun: www.youtube.com/watch?v=ekZkCjOcCKY. Or if you've got access to hot air surface mount rework tools, so much the better.
  7. Remove the 8 pin surface mount integrated circuit pointed to by arrow #3. Note that this is an "exposed pad" surface mount part. That means it's got an integral, exposed heat sink pad on the bottom of the chip that's soldered to the circuit board ground plane. You can't replace this chip with a plain soldering iron since that won't unsolder the pad beneath the chip. You can fry the circuit board if you overheat things in this process. If your heat gun didn't come with a nozzle attachment to focus the heat into a smaller area, make one out of aluminum foil and attach it to your heat gun. You can use a hair dryer or another heat gun to heat the back side of the board. Be careful as heat guns get REALLY hot and can burn the board, make other parts fall off, or burn your body.
  8. Now that you've got the chip off the board, clean the pads with a regular soldering iron and some solder wick or stripped, stranded wire and flux.
  9. Apply solder paste to the pads, including the large pad at the center.
  10. Place the MP2363DN-LF you bought from Mouser onto the site where you removed the old chip.
  11. Using your heat gun, preheat the board and then focus heat on the new chip until the solder flows. Keep the heat on a bit longer to be sure the solder flows on the exposed pad under the chip.
  12. Re-install the board in your TV.
  13. Enjoy.

post #8 of 8
Hello. I replaced the 1000uF and 820uF capacitors on my Samsung and I still have the clicking problem. When I check the voltage at arrow #1 it reads 1.043 Volts. That is very close to 1.1 so I am guessing my voltage regulator isn't bad. Or is it? I am a circuit board newbie so any advice would be greatly appreciated.

Should I replace the 470uF capacitors on the board just to be safe? They don't seem to be bulging or leaking.

Please let me know if my TV is just finally dead. lol

Thanks for any help.

Phil H
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