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Samsung LN40A750 Dying. Is it fixable?

post #1 of 30
8/29/11 at 12:38pm
Thread Starter 
I have a Samsung LN40A750 for about 2 years now and we have been having a problem with it.

The picture starts off jumbled and then gets better after 10 to 15 minutes.
Sometimes it takes longer.
This has been going on for a few months now.

I don't have the money for a new TV yet and I'm wondering if it is fixable and what the cost might be?

ANY help is appreciated!

Here are some pics of the issue:
TV just powered ON




TV after a few minutes



TV finally back to normal
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post #2 of 30
8/29/11 at 1:12pm
I tell Samsung owners who are having difficulties with start up to call Samsung customer service, get the serial number off the side of your tv, and see if your tv is one of the many covered by their free, out of warranty, power board replacement. They've had so many problem with the capacitors on the boards going out that they authorized the out of warranty repair.

If your serial number is on their list, they send a repair person to replace the board for free. I think the A series is included.
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post #3 of 30
8/30/11 at 8:08am
Thread Starter 
Quote:
Originally Posted by mes444 View Post

I tell Samsung owners who are having difficulties with start up to call Samsung customer service, get the serial number off the side of your tv, and see if your tv is one of the many covered by their free, out of warranty, power board replacement. They've had so many problem with the capacitors on the boards going out that they authorized the out of warranty repair.

If your serial number is on their list, they send a repair person to replace the board for free. I think the A series is included.

It's not a startup issue though.
It powers on just fine. Problem is just how the video looks after it turns on.

Is the Video problem a symptom associated with the power board problem?
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post #4 of 30
8/30/11 at 10:56am
Many odd problems have been reported by people with failing power boards. Check the link below for a complete description, and below the article, many posters have added their input.

As you can see from the list of effected tvs, the A's are included. It doesn't hurt anything to get the board replaced, it's free and it can possibly fix your problem.

http://www.crovean.net/samsung-lcd-tv-power-up-problem
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post #5 of 30
8/30/11 at 11:20am
Thread Starter 
Quote:
Originally Posted by mes444 View Post

Many odd problems have been reported by people with failing power boards. Check the link below for a complete description, and below the article, many posters have added their input.

As you can see from the list of effected tvs, the A's are included. It doesn't hurt anything to get the board replaced, it's free and it can possibly fix your problem.

http://www.crovean.net/samsung-lcd-tv-power-up-problem

Called Samsung.
They told me some tests to run and gave a me a service center location info.

But he pretty much said it's not the power board since it is turning on okay.
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post #6 of 30
9/2/11 at 12:41am
Quote:
Originally Posted by Majoram View Post

Called Samsung.
They told me some tests to run and gave a me a service center location info.

But he pretty much said it's not the power board since it is turning on okay.

The symptoms you described is EXACTLY how the bad capacitors cause the problem!

This happens all the time on all power supply boards that are of high density, capacitors are located near heat sinks that radiate heat, the capacitors themselves are underrated (in Volts) AND improper type that cannot deal with high frequency ripple found in switching mode power supplies, the whole power supply gets warm... and what not. This causes the electrolyte inside the capacitors to dry, the capacitors lose capacitance and start "injecting" high frequency ripple into DC power supply rails. This upsets the processing sections EVERYWHERE in the TV.

On cold start-up, the above is most obviously shown... the capacitance "restores" as the capacitor start to heat-up.

There's possibility that you have a cold solder joint as well.... however, this would still be located on the power supply board!

Call again, demand to talk to someone who apart from knowing how to lift the phone knows tiny bit about electronics as well (maybe samsung employs idiots on purpose -> to reject perfectly legitimate claim with their idiotic answers!)

10 years ago I sworn no sumsung product will ever enter my household -> still going strong

Boky
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post #7 of 30
9/2/11 at 5:29am
Thread Starter 
Quote:
Originally Posted by Extreme_Boky View Post

The symptoms you described is EXACTLY how the bad capacitors cause the problem!

This happens all the time on all power supply boards that are of high density, capacitors are located near heat sinks that radiate heat, the capacitors themselves are underrated (in Volts) AND improper type that cannot deal with high frequency ripple found in switching mode power supplies, the whole power supply gets warm... and what not. This causes the electrolyte inside the capacitors to dry, the capacitors lose capacitance and start "injecting" high frequency ripple into DC power supply rails. This upsets the processing sections EVERYWHERE in the TV.

On cold start-up, the above is most obviously shown... the capacitance "restores" as the capacitor start to heat-up.

There's possibility that you have a cold solder joint as well.... however, this would still be located on the power supply board!

Call again, demand to talk to someone who apart from knowing how to lift the phone knows tiny bit about electronics as well (maybe samsung employs idiots on purpose -> to reject perfectly legitimate claim with their idiotic answers!)

10 years ago I sworn no sumsung product will ever enter my household -> still going strong

Boky

It's been a while but I actually understood that
I'll try again.

Just curious but what brand do you go with?
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post #8 of 30
9/2/11 at 8:59am
Thread Starter 
Called again. Got someone a little more cooperative but my model is not on their list.
Sigh...

So either I pay or fix it myself.
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post #9 of 30
9/2/11 at 1:00pm
If you're comfortable soldering, it'll be easy to spot which caps need replacing (they'll be visibly bulged). Otherwise having it fixed should be pretty inexpensive. An in-home visit shouldn't cost more than $150 (plus tax) to fix it (assuming it is of course caps).
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post #10 of 30
9/2/11 at 1:44pm
Quote:
Originally Posted by Majoram View Post

It's been a while but I actually understood that
I'll try again.

Just curious but what brand do you go with?

Sharp seems ok....

Boky
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post #11 of 30
9/12/11 at 10:20am
Thread Starter 
Just an update.

So I opened it up and I couldn't find anything wrong visibly with the caps.
My soldering equipment is quite crappy. So I just tried a little re-soldering of the connections.

It SEEMED like the TV started up faster and cleared up faster but after a day it's back to the usual.

1) Anyone know where a I can buy reasonable Soldering equipment and GOOD replacement CAPS?? I think I will see if replacing them will help.

2) Took some pics, so if anyone can tell me if anything seems wrong, please let me know.








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post #12 of 30
9/12/11 at 10:48am
If ur intending to go DIY, here are some reasonably priced good soldering equipment. Don't have to buy the most expensive one, middle-road OK.

http://www.mpja.com/productsdirect.a...item5=17204+TL
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post #13 of 30
9/13/11 at 2:58am
Hi Majoram,

Read my post (#6) again:

"There's possibility that you have a cold solder joint as well.... however, this would still be located on the power supply board!"

… you’ll need solid quality multimeter (the CRO would be nice… Service Manual as well…) and a can of freeze spray.

Good luck,
Boky
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post #14 of 30
9/13/11 at 6:39am
Thread Starter 
Quote:
Originally Posted by Extreme_Boky View Post

Hi Majoram,

Read my post (#6) again:

"There's possibility that you have a cold solder joint as well.... however, this would still be located on the power supply board!"

… you’ll need solid quality multimeter (the CRO would be nice… Service Manual as well…) and a can of freeze spray.

Good luck,
Boky

Actually your post is why I tried resoldering the joint Thanks btw!

I think an Oscilloscope/Multimeter may be a bit much.
Rather than ID the faulty joint/cap, I was just going to get a new soldering iron and replace all the capacitors.

I haven't done electronics repair in a while, so I'm a bit out of touch.

I assume the CRO/multimeter is to check the capacitor waveform??
Also, what is Freeze Spray for??

Quote:
Originally Posted by MrBobb View Post

If ur intending to go DIY, here are some reasonably priced good soldering equipment. Don't have to buy the most expensive one, middle-road OK.

http://www.mpja.com/productsdirect.a...item5=17204+TL

Thanks! I was also looking at this one:
http://www.amazon.com/Weller-WLC100-...5919746&sr=1-1

or this one:
http://www.amazon.com/gp/product/B00...cm_cr_asin_lnk

What about the capacitors?
I'm not sure how to tell which are good quality ones.
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post #15 of 30
9/13/11 at 7:38am
The problem with the distorted video is not a capacitor problem. This is a panel problem (probably a tab bond). When the problem occurs, try squeezing the top corners of the set and see if the problem goes away. You can also grab opposite corners (top left/bottom right or vice versa) and GENTLY rack the panel. Again, if the problem changes, you will have confirmed a panel problem.
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post #16 of 30
9/13/11 at 8:03am
Thread Starter 
Quote:
Originally Posted by EG3 View Post

The problem with the distorted video is not a capacitor problem. This is a panel problem (probably a tab bond). When the problem occurs, try squeezing the top corners of the set and see if the problem goes away. You can also grab opposite corners (top left/bottom right or vice versa) and GENTLY rack the panel. Again, if the problem changes, you will have confirmed a panel problem.

What is the tab bond problem? Is it fixable?

Also am I squeezing it with the back plastic cover on or off?
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post #17 of 30
9/13/11 at 8:27am
Cover on so you don't accidentally electrocute yourself from high voltage to the back-lights! A tab bond is a panel ribbon cable connection within the frame of the panel. There are some posts on here about some people having some success in correcting the problem at least temporarily. But the fix is only a band-aid type repair. It involves partially disassembling the panel and placing a cushion over the affected tab bond. Try searching for some Sony LCD posts by OnlyTono. Perhaps some other members here have some other ideas, resources, or links.

Start here: http://www.avsforum.com/avs-vb/showthread.php?t=1173106
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post #18 of 30
9/13/11 at 8:30am
Thread Starter 
Quote:
Originally Posted by EG3 View Post

Cover on so you don't accidentally electrocute yourself from high voltage to the back-lights! A tab bond is a panel ribbon cable connection within the frame of the panel. There are some posts on here about some people having some success in correcting the problem at least temporarily. But the fix is only a band-aid type repair. It involves partially disassembling the panel and placing a cushion over the affected tab bond. Try searching for some Sony LCD posts by OnlyTono. Perhaps some other members here have some other ideas, resources, or links.

Start here: http://www.avsforum.com/avs-vb/showthread.php?t=1173106

Found the info! Thanks!
Thread I read though don't mention what material they used for the cushion.

Any suggestions? I'm concerned with the heat melting what ever material I use.
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post #19 of 30
9/13/11 at 8:44am
I use the soft pliable material that I find on heat-sinks. Not sure what it is called. LG sometimes calls it "chocolate". I'm sure there are numerous substances that would work. Time for someone with more experience in this procedure to chime in.
Good luck Majoram!
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post #20 of 30
9/13/11 at 8:46am
Thread Starter 
Quote:
Originally Posted by EG3 View Post

I use the soft pliable material that I find on heat-sinks. Not sure what it is called. LG sometimes calls it "chocolate". I'm sure there are numerous substances that would work. Time for someone with more experience in this procedure to chime in.
Good luck Majoram!

Ah thermal pads. Thanks again!
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post #21 of 30
9/13/11 at 12:23pm
Quote:
Originally Posted by Majoram View Post

What is the tab bond problem?

The flat cable connection(s) to the edge of the panel.

When it's happening, use both hands and use your palms to press firmly along the edges of the TV, if this has effect on the picture, then u have the above problem.
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post #22 of 30
9/13/11 at 1:11pm
My LN-T5271F is doing the exact same thing...

F**K Samsung. $3300, decided to go for an expensive fancy model (at the time) intentionally with a lot of research.

I had to have the panel replaced once month after buying it, a huge area of dying pixels started. Then the Samsung tech required my time to help out with the repair. Cheesy.

Now this problem. I am going to get them on the line as suggested here.
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post #23 of 30
9/13/11 at 1:33pm
Man I love AVS, I did exactly what the first poster said... and as he mentioned, they've had so many problems with these sets that you get one free out of warranty repair (that was also how the Samsung customer service agent just described to me).

When he said, "So you are having an issue with it powering on"
(I am not, just scrambled image issues)
I said, "yeah, trouble with the image coming up"

Just have to call them out on it. He originally tried to deflect my inquiry saying my first repair was the one time free repair, to which I corrected him, that repair was 2 months after I bought it, under warranty.

Still not going to buy another Sammy.
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post #24 of 30
9/13/11 at 3:09pm
Well the first Samsung agent that said Samsung would cover the repair out of warranty did not document his promise in the service ticket he opened for me. So the local repair partner won't move on it. I was even careful to discuss scope with this agent to make sure I wasn't going to be left high and dry on some technicality like my TV is mounted towards the west therefore the repair won't be covered.

I call Samsung back, not the same person of course, and this new person doesn't have record of who the first agent was, and he didn't write anything in the ticket, so the second agent can't speak to the promises made.

Man, sometimes its amazing how much humans have achieved, other times it seems amazing to me that we even have spoons.
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post #25 of 30
9/13/11 at 11:47pm
Quote:
Originally Posted by cmschleich View Post

Man I love AVS, I did exactly what the first poster said... and as he mentioned, they've had so many problems with these sets that you get one free out of warranty repair (that was also how the Samsung customer service agent just described to me).

When he said, "So you are having an issue with it powering on"
(I am not, just scrambled image issues)
I said, "yeah, trouble with the image coming up"

Just have to call them out on it. He originally tried to deflect my inquiry saying my first repair was the one time free repair, to which I corrected him, that repair was 2 months after I bought it, under warranty.

Still not going to buy another Sammy.

Good luck.... as stated above, the problem may be related to TAB's.... that is an expensive repair; just be persistent and you may end up with the new set!

Boky
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post #26 of 30
9/14/11 at 6:32am
Thread Starter 
Thanks all for the help!!

Last night I confirmed it was the tabs. Pressed a corner and the TV is working perfectly now.
I'll try a repair/bandaid solution later on.

The TV just hit 2 years old. I'm wondering if to bug Samsung about this.
Considering all I've read about Samsung now, next TV is definitely going to be a different brand.

Quote:
Originally Posted by EG3 View Post

I use the soft pliable material that I find on heat-sinks. Not sure what it is called. LG sometimes calls it "chocolate". I'm sure there are numerous substances that would work. Time for someone with more experience in this procedure to chime in.
Good luck Majoram!

Quote:
Originally Posted by MrBobb View Post

The flat cable connection(s) to the edge of the panel.

When it's happening, use both hands and use your palms to press firmly along the edges of the TV, if this has effect on the picture, then u have the above problem.

Quote:
Originally Posted by Extreme_Boky View Post

Good luck.... as stated above, the problem may be related to TAB's.... that is an expensive repair; just be persistent and you may end up with the new set!

Boky
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post #27 of 30
9/14/11 at 6:58pm
Quote:
Originally Posted by Majoram View Post

The TV just hit 2 years old. I'm wondering if to bug Samsung about this.
Considering all I've read about Samsung now, next TV is definitely going to be a different brand.

In Samsung's defense, when you own 17% of the world market share of televisions, there's going to be a lot more reports of problems than other brands.

(Citation: http://news.cnet.com/8301-31021_3-10454971-260.html)
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post #28 of 30
9/14/11 at 7:03pm
Quote:
Originally Posted by FadedMaster View Post

In Samsung's defense, when you own 17% of the world market share of televisions, there's going to be a lot more reports of problems than other brands.

No need to defend any one brand. Pick a brand, any brand, and you will see complaints about it.
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post #29 of 30
9/14/11 at 7:14pm
Quote:
Originally Posted by MrBobb View Post

No need to defend any one brand. Pick a brand, any brand, and you will see complaints about it.

How true!!!
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post #30 of 30
6/28/12 at 11:46am
Thread Starter 
Quote:
Originally Posted by EG3 View Post

Cover on so you don't accidentally electrocute yourself from high voltage to the back-lights! A tab bond is a panel ribbon cable connection within the frame of the panel. There are some posts on here about some people having some success in correcting the problem at least temporarily. But the fix is only a band-aid type repair. It involves partially disassembling the panel and placing a cushion over the affected tab bond. Try searching for some Sony LCD posts by OnlyTono. Perhaps some other members here have some other ideas, resources, or links.


Start here: http://www.avsforum.com/avs-vb/showthread.php?t=1173106

Just wanted to update/resolve this old thread.

The problem reached a point where the screen was so dark, you could barely see anything.
Only with cartoons you could see most of the picture.

We lived with it for a while but now it was no better off than getting TV on the radio smile.gif

So I finally bit the bullet and did the fix in the thread above.
The picture is absolutely perfect now smile.gif

I used the same "bumpers" from HomeDepot that they mention in the thread.

Thanks for Nothing though because now I don't have any excuse to get a new TV!!!
Just kidding tongue.gif

Thanks for all the Help! biggrin.gif
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