How to repair a Samsung LE40M87BD LCD TV

The other day my TV suddenly turned itself on. I turned it off again, but sure enough after about 30 minutes it was on again. It didn’t take long before the TV was unable to start at all. When I pressed the power button, the TV started to click and the red status LED flashed. I suspected that it didn’t get enough power to start. To me this sounded like some kind problem with the power supply, probably a bad capacitor. Sure enough, after opening the TV, I found three capacitors that were in bad shape, and after replacing them with new ones, the TV works perfectly again!

I suspect that this is a quite common problem, and this solution is probably applicable to more models starting with LE40. However, if you have a model that starts with LE40R*, then this solution might not be enough since there is a memory on the logic board that could have been broken when the capacitors failed. Since it is a quick, cheep and quite easy fix, it might at least be worth to open your ”broken” TV to see if it suffers from the same problem as mine. I payed 5$ for the capacitors, and you can probably get them even cheeper on eBay.

Preparations

This is a pretty simple repair, and you don’t have to have any great soldering skills, but you do need a few tools and of course new capacitors to replace the broken ones with.

Tools

  • Screwdriver, PH2
  • Soldering Iron
  • Solder
  • Solder sucker
  • Wire cutter
  • 3 pcs of 1000uF 16 or 25V electrolytic capacitors

Step 1, open the TV.

Put the TV on a soft surface (like a bed) with the display facing down and remove all screws holding the back together. After all screws have been removed, you should able to lift the back cover right off.

1. back_open

Step 2, look for any bad caps on the power board.

The power board is the white circuit board in the middle of the TV, (the capacitors that were broken on my TV has been marked byd arrows in the picture above). You can tell if the capacitor is broken or not by looking at it. It should have a nice flat top. If the top of the capacitor is bulging, it is broken or damaged. If you are unsure, compare it with the other capacitors around it. They should look the same.

Step 3, Desolder the broken capacitors

Now it is time to remove the broken capacitors! Start by removing the power bard from the TV, unscrew all screws and and disconnect all wires to be able to remove the card from the TV. After removing the card, locate the solder joints for the bad capacitors on the cards backside, the green side. In my case the capacitors were CM811, CM812 and CM817. Use the soldering iron to heat the solder joints, when the solder turns liquid, use the solder sucker to remove the solder. If you have problems melting the existing solder, try adding some new solder on top of the existing solder joints. This might sound counter productive, but when we add more solder we create a bigger surface for the soldering iron to heat and this makes it easier to heat it. Once you have removed as much solder as possible with the solder sucker, you should be able to remove the capacitors by hand. Be a bit careful when you do this, since there is a risk that you will brake the copper conductors on the circuit board if you bend to much. It can help to add some more heat with the soldering iron while bending if you have problems to remove the bad capacitors.

Step 4, Mount the new capacitors

The existing capacitors that broke were 1000uF 10V capacitors. Since they broke, I suspect they were under-dimensioned. There for I replaced them with 1000uF 25V capacitors instead. What is important here is that the capacitor that you use is 1000uF and at least 10V, so anything above 10V is also ok. I would recommend using 1000uF 25V capacitors. I got mine from the local TV-repair shop but you can also easily find them on eBay.

These capacitors are what is called polarized, that means you have to connect them the right way. To see which of the capacitors legs is the anode (+) look at the length of it, the longest leg is the anode (+). Almost all capacitors are also marked with a (-) on the capacitor housing indicating which leg is the cathode (-). Thread the capacitors leg through the holes and make sure the anode is in the hole marked (+) on the circuit board. Now solder the new capacitors in place and clip the legs of the new capacitors close to the board to make sure they don’t cause any short circuits.

Hopefully you will now have a working TV again.

Annonser

3 comments

Kommentera

Fyll i dina uppgifter nedan eller klicka på en ikon för att logga in:

WordPress.com Logo

Du kommenterar med ditt WordPress.com-konto. Logga ut / Ändra )

Twitter-bild

Du kommenterar med ditt Twitter-konto. Logga ut / Ändra )

Facebook-foto

Du kommenterar med ditt Facebook-konto. Logga ut / Ändra )

Google+ photo

Du kommenterar med ditt Google+-konto. Logga ut / Ändra )

Ansluter till %s