Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

[tom66]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

The inverter tries to keep the current through each bulb, to do this it needs to keep each transformer at the same voltage output. If this cannot be done (current too low due to bulb too short), the output voltage will rise, and the inverter will enter error/protect mode.

[johnboy1313]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

So, in theory, if all of the bulbs were short, it might work?

[tom66]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

I'm not sure. The current must be kept equal between each bulb. But it also has a maximum output voltage and current.

[johnboy1313]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

Per the attached and modified schematic, I was able to get the upper 12 lights to remain lit with only three transformers. I removed the components that are crossed out in red and ran jumpers where the green lines are drawn in. For the high voltage jumper between 5 & 6 (circled), I used a piece of 1/8", insulated, solid copper wire, run through a small length of silicon tubing to add more insulation (see pics). I plugged the IP board in and the remaining 12 bulbs lit and remained lit. I only left it on for about 10 seconds. I just wanted to see if they would stay lit. At this point, I should now be able to test the 13th original bulb to verify that I only need to replace the one bulb and I should also be able to confirm that my modified shorter bulb does not work.

[johnboy1313]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

Does this look odd to you too?

[tom66]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

Does the set remain on indefinitely with that jumpered?
Have you tried swapping bulbs from dead area to working area?

[johnboy1313]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

With one of the 12 working bulbs removed, the remaining 11 shut off after a second or two. The same thing happens with a modified, shorter bulb in. With the 13th bulb in place of one of the working 12, they all stay lit, so it looks like I just need to replace the one bulb. However, I don't like the looks of the ends of the two in the one picture below, and I don't like the dark spot on the other bulb in the other picture below. I may be in the hunt for 4 bulbs.

[johnboy1313]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

Forgot to add pics

[tom66]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

This:
https://www.badcaps.net/forum/attach...7&d=1372538420
just looks like mercury sputtering in the tube. Not a major issue IMO. (Mercury is what converts (into visible light) the ultraviolet light that the neon-xenon gas discharge creates.)

However, these tube(s):
https://www.badcaps.net/forum/attach...6&d=1372538420
are clearly showing signs of arcing.

[budm]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

If you check the temp of that middle tube (the arcing one) end, it will be higher the other. I have seen them glowing red hot.

[johnboy1313]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

Picked up a broken screen KDL40V2500 yesterday for $10. Just tore it open and scavenged a bulb from it for testing. The salvaged bulbs work.

Long story short, my wife and kids are out of town until Friday, my oldest friend is in town from Arizona, unannounced, for a week, and I'm off work until Monday the 8th. I have a pocket full of money, a best friend to hang with, and more free time than I know what to do with. I'll post pictures of the TV when I get around to it.

[johnboy1313]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

I went ahead and swapped out all fourteen bulbs. They all had at least one blackened end. I figured if three of the fourteen were already bad, it wouldn't be long until the remaining eleven went out. I wonder if the previous owner didn't just leave this thing on all the time. All in all, I may have damaged that "bad" transformer pulling it out of the original board, so I might not have really needed to buy the IP board. Considering the condition of the bulbs, the original IP board was probably past it's prime anyway, so at $20 for the new board, I can't be too upset.

[tom66]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

Put TV in standby mode then press Mute 1 8 2 Power to find out power up hours. Most CCFLs should reach 20,000 hrs with no problems, 60,000 hrs is typical lifetime.

[johnboy1313]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

So this thing's still not right. After about two hours, half of the screen goes a small but noticeable difference darker. There's a perfect line down the middle. If you turn it off and right back on, it goes away for a few minutes. Changing the source seems to make it go away too. I accidentally hit the source button and it corrected itself. I went back to the original source and it worked fine. At that point I shut it off. I'll look at it later. Any ideas?

[tom66]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

Could be a loose connector on the T-con side (two ribbons), or perhaps Demo Motion 120Hz/Store Demo (DNIe) is switched on.

[johnboy1313]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

Doesn't seem to be a loose connection or a demo mode that I can find. It really seems to be heat related. The inside of the entire set is brown and almost burnt looking. It's weird. I don't have an IR thermometer, but the metal cover over the T-Con board gets too hot to keep your hand on. The tab-bonds that connect the panel to the left and right PCB's get ridiculously hot too. In fact, the heat coming off the entire set is such that you can feel it from three or four feet away (~1 meter).

At this point, I have two theories.

A) The T-con is faulty and getting so hot that it's causing one side of the screen to dim slightly.

B) The screen itself is faulty and causing the T-Con to get hot.

I'm leaning towards B. At any rate, I'm convinced it's heat related. Apparently, when I was able to get the issue to disappear by changing the source, it was a fluke. I haven't been able to do that since. I've had the panel apart to expose the tab bonds and the boards bonded to the panel (whatever they are called) but there is no change when pressing or flexing the tabs. The only thing that seems to make a change is to shut it off. The longer it's off, the longer it takes to show the fault again.

I've attached several pics. With the test patterns active, the fault is more prominent on a grey screen, slightly visible on the white screen, and not noticeable at all on a solid color. I'm not sure what to make of it.

Any thoughts?

[johnboy1313]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

Anyone?

[tom66]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

So if you put the panel on a black only test pattern does the black level vary as you look down the panel or is it fixed?

[johnboy1313]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

It seems to be fixed. There's no distinguishable difference.

[tom66]

Re: Samsung LN40B630N1FXZA, brief backlight, power up chime, then nothing.

OK, I'd be saying panel myself. I can't see how a T-con could cause that problem but I've not seen said problem before.