Help with the Inverter or Bulb.

Hey guys,

I know this topic is all around the web, but I just can't seem to find a solid answer. I own an old Dell M1330 with an LCD display that's just over four years old. The screen failed about a week ago. I want to say that the bulb is the problem, but it could also be the inverter, as it is more likely to fail from what I've found online. This is what I've gathered.

I can see very dark image if I shine a light down from the top of the screen.

If I plug my laptop into screen via VGA there are no issues.

Prior to failure, the screen would often flicker on the desktop. My desktop is rather dark, so I suspect that it was having issues showing certain degrees of brightness.

As of right now, when I open the lid of my laptop (set to just turn off the screen when the lid is closed) the screen illuminates for a fraction of a second and goes dark.

I tried doing an inverter test as outlined on the first link below using a multimeter with a frequency range of up to 4MHz. However, the meter won't pick anything up around 30kHz. I get an odd 60Hz if put the leads anywhere near the laptop whether the screen is on or not
LCD Inverter Test - Laptop Testing for Backlight or Inverter Failure
http://www.radioshack.com/graphics/uc/rsk/Support/ProductManuals/2200812_PM_EN.pdf

What do you guys think is the problem?

On a side note, does bulb mean the same thing as backlight as does CCFL?

Thanks,
Josh

 

Yes, it's the same.
Can you hear any noise during flickering?
I had similar sympthoms with my notebook but that was electrical breakdown to the ground (wire from inverter to bulb were with damaged insulation and sparked breakdown to metal frame). No bulb, no inverter.
Check all wires and contacs.

 

I did not hear anything when the screen flickered. As for sounds, at the moment, when I open the lid, I can hear a very soft high frequency sound. Its like when you turn on a TV but softer. It goes out in less then a second though.

 

For me it sounds like you've got broken wire somwhere between inverter and lamp.
Check wires and contacs.
Good luck!

 

Yeah... I'm leaning towards the lamp since the computer flickered, kind of like a dying floro tube.

 

That's not critical term for backlight lamp. My old hp pavilion still working since 2002.

 

From the diagnosis you did and saw it to me would indicate a bad LCD back-light since you were still able to shine a light on the screen and make out the images. And plugging it into a VGA ext would indicate that the GPU isn't the problem but more related to the actual LCD going bad and replacing it would be what you have to do. I think CCFL aka back-light is the same name just said differently. As to if the inverter is bad you have to find a another computer with a good inverter and swap those out to be sure as well. So you will either end up with buying a LCD or getting the cheaper inverter and try that out and if the problem persist then that means the LCD needs to be replaced. Also check your LCD wiring harness as well sometime that might the cable is bad and replacing that might fix it as well. I do know I bought a HP dv5 with bad LCD from what the seller told me but I first bought a lCD cable and that fixed the flickering problem. That could also be the fix as well as my dv5 the seller always grabbed the LCD thus somehow causing the cable to go bad from the stretching. But as you see there so many diagnosis you have to first eliminate before buying a LCD as that is the most expensive part of the replacement.

 

Not a good comparison.
My Dell Inspiron 1300 had its backlight die on it after only 2 years (and it was bought in 2006) which was confirmed and replaced in late 2008 (in one of the repeair shops in London - waited 24 hours and paid 40GBP).
Granted, that laptop fell on the floor (accidentally) twice in those 2 years before the backlight died (which probably contributed) but other than that, my Acer 5930G (the laptop in my signature) has a non functioning backlight (this one never fell on the floor nor was it mis-treated - and it was bought in 2008) - am currently using an external monitor until I can order a new backlight (or a LED conversion kit).

The reason why I highly suspect the backlight in my Acer is because my screen was flickering for a few weeks, until one morning, I woke up, turned on the laptop, went online, and after 5 mins of it working (with the usual screen flickering), I just saw the screen dimming from bright to pitch black in roughly 10 seconds (and then just staying like that).
If the inverter was responsible, then the power to the bulb would likely have been cut off abruptly instead of slowly (of course, there's a background image if I shine a bright light on the panel itself and my webcam works as well).
Either way, my situation reeks of the bulb going out.

I think the backlights are much more prone to failure that people want to give them credit for.
Usually the inverter is to blame, but practically no one I met who had similar issues to mine had inverter problems (instead it was always traceable to the backlight).

 

Comparing LCD longevity is like comparing the longevity of just about any other electronic product. Some makes and models have a lower failure rate than others, but it's a moot point, as LCD lamps have a given planned obsolescence or approximate life span. It's like saying a car motor is more likely to fail after 100k miles; true that within that time frame is the prime of the engine's life, but at the same time, there are engines on the road with several hundred thousand miles that still [barely] run.

Anyway, a dimming display has often alluded to a bad inverter in my experience, but the only way to know for sure would be to take bug999's advice; check your cables and contacts, and then if necessary, replace first the inverter and see if that fixes it. A new inverter logic board will probably cost less than a new LCD screen, but it's your call on what order to troubleshoot.

 

I tightened down the wires leading to the screen and inverter today. However, the backlight does not stay on for longer then 1 second. I ordered a $15 backlight off ebay. Anyone know how difficult it is to change out the backlight? The one I bought had the wires already attached to the backlight.

 

I don't have experience in swapping the lamp(s), but hopefully this will help you out: LCD Backlight Removal & Replacement | laptop screen fix | - YouTube

 

The backlight can be a bit tricky to install given its position inside the screen panel, and then of course, you have to take into account that the backlight is relatively fragile (could break easily).
The latter is one of the reasons I'm contemplating on converting my Acer 5930G from backlight into LED lit screen instead.

 

I myself would advise against doing this unless you have the know how and experience and tools to do such repair as others noted is a delicate operation to do and not for the faint of heart to try. Try the inverter first that would be the least expensive cost to you. The LCD would be the most expensive depending on the model and serial number you have to match up with your current one.

 

If you have already got the bulb, you can check the inverter work WITHOUT INSTALATION new bulb into LID (monitor)
Just disconnect old bulb from inverter and connect new one laying aside. Turn the computer on. If new bulb will not work, you do not have to go thru this delicate and complicated bulb replacement.
It's just easiest way to find out what's realy wrong in system.
Good luck!

 

And, anyway, I would check the wires and contacts because even the inverter is ok but lamp has broken wire it will not work and you can not know for sure where was a problem.
In addition, a LID is a moving part so open-close procedure will finally cause wear&tear of cables, ribbons, wires, ect. affected.

 

The wires very seldom are exposed to such a degree of stress from opening and closing the lid that they go "bad", though the problem is most likely electrical.

Right, this a simple testing procedure that will tell you which component is faulty before you go through any major disassembly and hassle.

 

Hi, I've gotten a lot of information on this site and so I'm hoping someone can steer me in the right direction. I just pulled a bonehead move. I went to replace the inverter in my laptop and in my haste to get it fixed I totally forgot to unplug the power. So of coarse while I'm pulling the old inverter it sparked and now the computer is dead. Anybody have an idea of how much damage I may have caused? I don't have a clue where to look. Thanks for any info.

 

You might get more feedback from your own thread, but to answer your question:

No, but a spark is never a good sign! Does the system exhibit any symptoms of damage? Any beep codes, POST, or even power?

 

prostar, thanks for the reply. I have to say no to any symptoms except total silence and darkness. No beeps or even any power signs at all.

 

I don't think you can just take out the bulb as easily as mentioned here it is inside the protective covering and takes alot of care to take out and test and doing that will be more work IMO.

 

Yeah... I'm hoping its the inverter, but if its not, then I would need a new screen anyways. I might as well try replacing it. A new screen is around $90 unfortunately.

 

That was not about taking out the bulb. Looks, you've missed this:

 

As long as you sparked the inverter alone but not the system board, you should just be able to replace the inverter.

 

My backlight came in yesterday. It was definitely the backlight that was the issue, as the new backlight worked on the inverter. I replaced the backlight, and my screen works now. It was rather tricky to get the old backlight out. You pretty much need to take the screen down to the bare bones and reassemble.

Thanks for the help guys!