Can I test an inverter on a laptop?

[yello]

The misses' laptop screen has gone very dark. And I have tried turning up the brightness. Laptop itself works fine with an external monitor.

So I'm guessing it's either a screen or an inverter problem, hopefully the latter because that's cheaper to fix. A screen is around €150, inverter €20.

Anyone any ideas on how to test which is at fault though? Or which is the most likely... gut instinct tells me to take a punt on an inverter.

Incidentally, we took it into the local computer shop and asked for a fault diagnosis. Motherboards gone, they said, it's beyond economic repair... but we'll sell you another laptop and not charge you for the fault diagnosis. Thanks, I said, but I thought the motherboard/video card was ok if I could get an external monitor to work. Ah yes, he says, cascading problem... the motherboard was probably okay before but it's broken now. Hmmm, I say, how much for the fault diagnosis? Took the laptop back and came home. Yep, it still works with an external monitor.

 

[Piemaster]

Sounds more like the screen to me as its working with an external monitor. There is a very old laptop licking about this ship somewhere which is quite dark now and has a distinct orange cast to it (looks like it needs a degauss, obviously not though with an LCD screen).
I'm assuming by 'inverter' you mean the power supply? Easy to test. Leave laptop on until it goes flat and hibernates, then plug it back in. If it comes back to life its ok. Or if you have a multimeter you should get something like 18V DC at the jackplug that goes into the laptop (power supply will be marked with its output voltage)


BTW - pedantic mode- an inverter takes battery voltage to produce AC power, laptop power supplies do it the other way round.

 

[ColinJ]

Sounds more like the screen to me as its working with an external monitor. There is a very old laptop licking about this ship somewhere which is quite dark now and has a distinct orange cast to it (looks like it needs a degauss, obviously not though with an LCD screen).
I'm assuming by 'inverter' you mean the power supply? Easy to test. Leave laptop on until it goes flat and hibernates, then plug it back in. If it comes back to life its ok. Or if you have a multimeter you should get something like 18V DC at the jackplug that goes into the laptop (power supply will be marked with its output voltage)


BTW - pedantic mode- an inverter takes battery voltage to produce AC power, laptop power supplies do it the other way round.

No, he's talking about the inverter that takes the low voltage laptop supply and boosts it up to power the back lighting for the screen! See Laptop repair help.

 

[Crackle]

Might be the backlight itself, rather than the inverter and that is both tricky and delicate to replace.

 

[Wobblers]

When you say that the screen is very dark, can you still actually see anything on it? If the inverter's gone, you will be able to see the image if you hold a bright light to the screen - take it into full sunlight, for instance. If you can see something, then either the inverter or the fluorescent tube in the screen itself has died. The inverter's easy to fix, but the tube is more awkward: it can be replaced but that's not for the faint hearted!

P.S: the shop was telling you finest manure! They're trying to rip you off. You should speak to Trading Standards about that, it's just not on.

 

[yello]

When you say that the screen is very dark, can you still actually see anything on it?

Yes. The image is there just very very dark.

Thanks for the link CJ. Very useful and I'll bookmark that one.

There is no way I'm going to attempt a backlight fix, it sounds like something for someone who knows what they are doing! I can be a 'panel jockey' with the best of them though so it might just replace the inverter and see what happens. Worth a try I figure.

 

[Crackle]

It's possible to do the backlight Yello. I took one out of my bust screen but you have to cut all the sealing tape on the screen and wiggle things out carefully. As I wasn't really trying, I didn't cut the tape enough and wiggled the backlight too hard and it bust but if you can take enough apart to get to the inverter, you can manage the backlight.