Samsung LCD TV on Off Issue DIY Repair Fix

by TheCoffeeDude

19K11218

Intro: Samsung LCD TV on Off Issue DIY Repair Fix

We had a Samsung 32" LCD TV go on the fritz recently. The television would turn on, then immediately turn itself off, then turn on again...in a never ending cycle. After doing a little research, we discovered that there had been a recall on these televisions due to faulty capacitors used during manufacture.

We also discovered the recall had ended a couple of years ago.

Not wanting to buy a new TV or pay an estimated $150 to have it repaired, I grabbed my trusty soldering iron and went to work. It turns out that for only $3-$6 in parts, you can fix this problem yourself. The only skills it takes are some basic soldering and desoldering techniques. Here are a couple of excellent Instructables written by other authors explaining these skills:

Now on to materials...

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STEP 1: Materials

Do do this repair (other than a faulty LCD tv), you will need*:

*Links point to the specific item I used.

**Do yourself a favor and make sure to buy braid or wick with flux already in it.

STEP 2: Disassembly and Diagnosis

In almost every case, this particular issue is caused by one or more capacitors on the power supply board over heating. Finding an overheated capacitor is simple once you get the back off the television. Take pictures as you go in case you need to refer back to where things are, particularly on the circuit board.

Carefully remove the stand and the back of the television. Be sure you have a clean, flat surface to lay the television on face down, then remove the stand followed by the black screws around the outside of the back of the television. If all the screws have been removed, the back should lift up and off very, very easily. Do not force it.

The power supply board is on the right. If you look at the picture of the power supply, you will see a closeup of an burnt out capacitor. Notice the top is no longer flat, but has puckered up and separated. To remove the power supply board, Carefully unplug the two cables running to the board (one on the left and one on the top). Then unscrew the silver screws at the four corners. There will be an extra screw in the bottom left corner of the board where the power cord plugs in. This is noted on the picture. Do yourself a favor and screw the silver screws back into their holes so that you don't lose the screws or where they go.

Now we desolder...

STEP 3: Out With the Bad Part...

We mount the board in the helping hands, noting where the bad capacitor is located on the underside. We then desolder the connections, and remove the part. Did you remember to note which way the capacitor was mounted? Did you take a picture? The easy way to remember which way the capacitor goes is to remember which side the vertical stripe was on. If you need help desoldering, just consult the Instructable at the beginning of this one.

Now we solder in the new one...

STEP 4: ...In With the Good Part.

Making sure we have the capacitor mounted the right way, we now solder in the new capacitor. How did we know which capacitor to buy?

There are three key features that identify a capacitor. First, it's capacitance, second, it's voltage, and third, it's leads. There may also be a temperature specification as well. For our capacitor, all we need to identify a proper replacement is the nominal capacitance in micro-Farads (47µF), the working voltage in volts (160v), and finally, since both leads come out of the bottom, this is a radial capacitor (as opposed to an axial or snap-in capacitor).

I found ten of these on Amazon for 15 bucks. That's $1.50 to repair the TV, as opposed to paying $150. I don't mind buying 9 extra capacitors, because someday I may find a use for them.

Now we put it all back together right?

STEP 5: Test First, Then Reassemble.

Replace the power supply board in the TV (aren't you glad you didn't lose those screws?), plug the two cables back in, and then plug the TV in and verify it is now working. If it isn't, did you solder the capacitor in the right direction (+/-)? Is there more than one capacitor burnt out that you missed?

If you have verified that the television is working properly, replace the back and the stand and then enjoy the fruits (and savings) of your labor!

15 Comments

tytower 8 years ago

You need to make clear how you found the faulty capacitor . The picture does not look like it is blown up or expanded in any way .How will I find mine?

Clyde1020 7 years ago

The tops of mine were buldging. Hard to see in the picture without zooming in

Clyde1020 7 years ago

I can easily see them but that may be because I already know which ones they are.

tytower 7 years ago

OK well tha does not help others much does it . Can you add an arrow to your pictures or draw a mud map or something?

Clyde1020 7 years ago

Hi, sorry it took me so long. Been dealing with some health problems. Here's a picture with the buldging caps highlighted. Hope it helps.

mrcurlywhirly 8 years ago

Nice work! Good to see other people repairing their electronic equipment rather than replacing. I had a similar issue with a Samsung 226bw monitor, great picture quality for three years, then flickering and eventually failing to power up. It is pretty widely known (google it) that the cheap (rhymes with saxon..) capacitors in these units often drift out of spec after a few years, leading to these types of problems. I replaced all mine with a well known brand, problem solved, repair cost - around $15AUD total. For testing you can use a cap tester, or visually check for bulging, signs of leakage or heat degradation. As caps are cheap - even decent ones, I tend to perform debugging with a solder sucker (which i far prefer to braid) and a rubbish bin lol.

TheCoffeeDude 8 years ago

I have a spring-type solder sucker but haven't had much luck with it...any tips?

mrcurlywhirly 8 years ago

Support the cct board if necessary, then heat the solder until you have a fluid mass and have the nozzle of the sucker as close as possible to allow the vacuum to suck up the solder, press the button and byebye solder - works fine for me.

qpaul666 8 years ago

I had a similar problem with my Samsung. The difference being that I went on their website support and searched for known faults. I did find it in a list and then used the email to contact support, who were excellent. Arrange for an engineer to repair it free of charge, in a week.

TimoR3 8 years ago

Some people say that this kind of circuits were faulty already on the sketching board during planning. This company has used too low quality capacitors and has also placed them on the printed circuit board (PCB) too near the cooling fins of the switching powerfets and diodes. This causes too high operating temperature for the capacitors, thus leading too early drying. The internal resistance of the capacitor gets too high and the DC voltage is not able to be smoothened enough.

pfred2 8 years ago

When I recapped my Samsung I just replaced all of the power supply capacitors. They're all defective. That is why there was a recall. I think there were 4 of them? Although not all of the caps I replaced were bad when I did replace them. I doubt they were going to last very long.

mm0bef 8 years ago

The majority of the time most faults can be traced back to faulty capacitors in the low voltage side of the power supply. This applies also to most large electronic equipment. Pretty easy to fix if capacitor is obviously faulty butyou are better to replace all the electrolytics as another failure wont be far behind the first :)

pfred2 8 years ago

Taking your TV apart is not something you want to have to do on a regular basis.