Samsung LN40B650T1F won't power on

[tom66]

Re: Samsung LN40B650T1F won't power on

Maybe you haven't broken any bulbs, you can get lucky. Try lifting the TV up and see if you can hear broken glass. If more than one bulb is broken it's probably too expensive to replace them.

[tom66]

Re: Samsung LN40B650T1F won't power on

Transformer test: first transformer, 20000 ohm range (or autoranging ohms, if you meter is autoranging) across each pair red and black, avoid the middle short link. For every other transformer test as indicated, curved pairs of red/black probes (though technically orientation does not matter it can help you be consistent in your tests so you don't double test or omit one...)

Power to board must be disconnected or damage to meter could occur.

[MEB]

Re: Samsung LN40B650T1F won't power on

Here are the results of the transformer test. I am guessing the test is to look for uniform readings between the secondaries. Is there a percentage value that you guys use in your decision making of OK or bad and if too far out one would then remove from circuit and retest? I'm just trying to understand what your thoughts are.

And in remembrance of our old friend, “If you have problem understanding my language, you will always insist on owning a cheap meter and will lose the race."

[MEB]

Re: Samsung LN40B650T1F won't power on

Refresh

[MEB]

Re: Samsung LN40B650T1F won't power on

bump

[tom66]

Re: Samsung LN40B650T1F won't power on

The transformers are all OK, so I am guessing there is a bad bulb in the panel or some fault with the inverter circuit.

[MEB]

Re: Samsung LN40B650T1F won't power on

Thank you for the reply. Based on all your help, and the comments and experience from Glitcher and audofreak19, plus the fact that my buddy yanked the lamp sockets out as shown by budm, I think it is time to disasemble the lcd. Any documentation or helpful words of wisdom before the exploration begins? Any help is welcomed.

[Glitcher]

Re: Samsung LN40B650T1F won't power on

Its pretty simple to get to the backlights, the hardest part is getting the screen itself off without damaging it. Make sure you unhook any connections that block between the frame and the panel (usually the speakers, IR sensor, and buttons). Then just find any screws around the edge of the panel. The panel should easily lift up away from the frame if all the screws are off.

You'll then need to unscrew the metal frame of the panel that cover the tab bonds to release the lcd screen. The hardest part is gently and carefully getting the lcd screen out. It usually comes off easily (however in few cases it is slightly glued down... or itll be stuck in a tight fit between the black bezel)

After taking out the lcd screen, there will be a black bezel that needs to be removed. They are usually held on by latches on the sides. After that there are two white plastic pieces that cover the ends of the lamps. (They usually pull off easy on most panel or latched if not)

[MEB]

Re: Samsung LN40B650T1F won't power on

I'm back! Went to my friend's last night and worked on the screen. All was just like you guys said it would be. No lamps were damaged due to the mistake made with the sockets, and after getting the lamps exposed and firing the thing up, it looked just like Glitchers previous photo. I attached ours below. Thanks so much for the help getting this far. This site, thanks to the head stooge and its members has really put a spark back in my life, and I am truly grateful. No-one treats me like an idiot and I am learning so much. THANK YOU!

Now I need to find a 36" lamp. I will be in the hunt and would appreciate any guidance. Thanks again.

[MEB]

Re: Samsung LN40B650T1F won't power on

Only lamp I can find is from CCFL Warehouse and will have to find a way to measure the length more accurately, but best I can tell, it is 4mm X 895 or 900mm. Would one of these from them be OK? I have no idea, but if I don't hear back, will go ahead and get one.

[tom66]

Re: Samsung LN40B650T1F won't power on

Maybe have a look around for a similar 40" on craigslist with a smashed screen - CCFLs might be usable.

[MEB]

Re: Samsung LN40B650T1F won't power on

Having no luck on craigslist as of yet. Is buying a lamp from CCFL Warehouse not a good idea? Is your concern that the lamps will visibly look different as far as color output than the Samsungs or are there other reasons? I don't have any knowledge to make this decision. Just wondering what your thoughts are to help me understand your reasoning.

[tom66]

Re: Samsung LN40B650T1F won't power on

No major objections, just quite expensive so giving you alternatives; with a smashed set you'll get a full set of good bulbs (worst case a couple are cracked.)

[MEB]

Re: Samsung LN40B650T1F won't power on

OK, thanks for the clarification. I will keep watching craigslist for a while to see what treasures show up. I will let you know if I find something. Thanks again.

[MEB]

Re: Samsung LN40B650T1F won't power on

I have been unsuccessful in getting a donor set from craigslist. I am blocked by Websense at work and by the time I get home, all likely candidates have already been sold. Any hacks would be appreciated.

So I ordered a ccfl from ccfl warehouse and it has arrived. Tonight me and my buddy are going to attempt to install it. I will post back, hopefully with good news.

[MEB]

Re: Samsung LN40B650T1F won't power on

Yipee!!

Replaced that lamp and all lamps lit up bright and no flickering. What an adventure. Thanks to all for helping. I learned much and had a great time.

But ... If you revert back to post 20, I attempted to describe a horizontal line problem. I read about tab bonds and told myself if the lamp solved the main problem (which it did) I would check into that. My plans were to flex the tab bonds with my finger and watch the line to see if anything changed. So after the lamp was placed, I re-assembled enough to fire it up and still get to the tab bonds. I presses on each one repeatedly (boy, they get warm) I saw no effect on the line. So we reassembled the set. We were watching the fine picture for a couple hours and I will try to explain what I saw relating to this line. I don't know the terms but here goes.

This line is horizontal and the width of the screen. It is located at the very top of the image. If you are looking at an image which I will call widescreen, with large black borders, the line is the first scan line or row of pixels of the actual image. If you look at something like full screen, the line is still the first scan line or row of pixels in the actual image. So in layman's terms the line is not related to an actual row of pixels on the LCD but moves around with the actual displayed image. Don't know how else to try to explain it.

After staring at the thing for a long time, I discovered something else. This "line" is an actual duplicate "scan line" (sorry) which appears to be duplicated from another area of the screen. If you look at the total image, and watch the movement of objects on the screen, and imagine taking one horizontal row of pixels from 3-4 inches from the bottom of the screen and stick it on top of all the image, that is exactly what that line is composed of.

I read this over and even I can't understand what I am trying to say... be right back with a sketch...

See attachment.

The sketch shows my exagerated LCD composed of 10 horizontal rows of pixels. This is what I am seeing. I can't tell if the duplicated line is actually removed, but there is no visible gap in the area where it should be.

I don't know how but this is what I see. Hopefully you won't think I am nuts, but is this even possible?

[MEB]

Re: Samsung LN40B650T1F won't power on

refresh

[tom66]

Re: Samsung LN40B650T1F won't power on

Hmm, I have had the issue you describe before. In my case it was caused by the overscanning settings of the source being set wrong for the TV - a bug with the source's software not the TV. A quick fix in some cases is to turn off the "Just Scan" mode on the TV - in the picture size settings. This will hide the faulty row of pixels.

[MEB]

Re: Samsung LN40B650T1F won't power on

Thank you fine sir. Don't you start your new job pretty soon?

I had him go in and search around and although he didn't find "Just Scan", he found something called "screen fit" and he played around in that area and ended up on 16:9 and noticed no disappearance of the line. But he just bought a new 50" Samsung to replace the 40" in case we didn't get it fixed, and he said his wife noticed a similar line in the same area on it also. I guess he thought that information was not relevant.

You mentioned the source problem before. Is it possible that his provider is causing this? He says he never noticed this until about a year ago when they went full digital. The 40" is upstairs in a bedroom and has a different box then the 50" in the living room.

Am interested in what you have to say about that, or am I back to the drawing board?

[MEB]

Re: Samsung LN40B650T1F won't power on

refresh