Is this a bad inverter?

[CraiGDaniel]

Picked up a laptop cheap it's a dell inspiron 5720 (i think)

Basically the screen is extremely dark. Without straining or shining a torch on the screen you can't see anything. However when light is introduced or i look very closely i can see windows etc. Works normal on external monitor.

I removed the inverter and tried again, nothing changed.. as if it wasn't there in the first place.

Just wanted a second opinion as to if it is definately the inverter that causes this, as i'm new to doing inverters.

Cheers.

 

[PCX]

Its the inverter or backlight. Do you have another inverter or screen to test it with?

 

[CraiGDaniel]

Nope nothing about i can swap around. :/

If it is the back light, am i right in thinking i can buy any ccfl bulb with the same size as the screen?


As there are no bulbs specific for my laptop in the UK however there are lots of 15.4" bulbs that match the laptops spec.

 

[compnet]

Its the inverter or backlight. Do you have another inverter or screen to test it with?

Or the cable, or the board.

@Craig

Bulbs usually cost around half the screen and changing the bulb is very tough. I've tried removing them and its no fun.

 

[PCX]

Or the cable, or the board.

@Craig

Bulbs usually cost around half the screen and changing the bulb is very tough. I've tried removing them and its no fun.

Good catch! Totally forgot about those. They are less common, but most definitely a possibility.

 

[Kitten Kong]

Sounds like the actual screen to me. Easier and cheaper to replace the screen, than to replace the bulb.

 

[Jeffreynya]

ya, I am pretty sure you would have to unsolder the old bulb and resolder the new one in. For me I would rather just replace the whole screen.

 

[Winchester Computer Care]

Sounds like the actual screen to me. Easier and cheaper to replace the screen, than to replace the bulb.

Bulbs usually cost around half the screen and changing the bulb is very tough. I've tried removing them and its no fun.

If he can see an image when using a light source, it's definitely not the screen itself...a 15.4 ccfl bulb only cost about $12 USD ( http://www.lcdparts.net/CCFL13D.aspx ) and they are not very difficult to put in if you have a little patience.

I have changed out hundreds of them over the years...it only ads about 15 - 20 minutes to the time it would take just to change the screen.


The problem is most likely the bulb or the inverter...you need to find a way to test them.

 

[Patch22]

Taking screens apart to change a backlight is something I've found to be tricky and to take more than a few minutes!! LCD screen panels just aren't designed to be taken apart. Also, I've heard there is a high failure rate, and so although you may reduce the repair cost when compared to changing the whole screen your customer may be back on the phone again fairly soon.

With a darkened display fault I have a set diagnosis cost that includes initially changing the inverter. If this solves the problem then the customer pays for the inverter and repair. Otherwise I then quote to change the screen. If this is a no-go then they only pay the initial diagnosis cost. I potentially lose out on the cost of an inverter but I am slowly accumulating a good stock to use for testing...I am not a fan of screen faults that aren't just a straight forward smashed up LCD panel!

 

[Martyn]

You could buy a tester http://www.lcdparts.net/LST.aspx

 

[Patch22]

You could buy a tester http://www.lcdparts.net/LST.aspx

Wow! Never knew these existed..Will save me $$ and time, thanks. Do you use a tester yourself?

 

[Martyn]

Wow! Never knew these existed..Will save me $$ and time, thanks. Do you use a tester yourself?

No i did look at getting one but I have several test screens and invertors so I tend to bumble my way around problems. I still might get one. This has been posted on the forums several times so it's not my find.

 

[CraiGDaniel]

got a ccfl bulb 15.4" for about $4.50 and the inverter was the same price.


ordered both so hopefully i'll get it fixed. Changing the bulb doesn't look to painful. I have a soldering iron and what not if it comes to it


Hopefully all goess well lol

 

[Winchester Computer Care]

Taking screens apart to change a backlight is something I've found to be tricky and to take more than a few minutes!! LCD screen panels just aren't designed to be taken apart. Also, I've heard there is a high failure rate, and so although you may reduce the repair cost when compared to changing the whole screen your customer may be back on the phone again fairly soon.

I have never had a replaced bulb come back due to failure, and as I said above...changed out hundreds of them over the years. I guess it's like most things, the difficulty of the task is directly proportional to ones level of experience.

 

[Patch22]

I have never had a replaced bulb come back due to failure, and as I said above...changed out hundreds of them over the years. I guess it's like most things, the difficulty of the task is directly proportional to ones level of experience.

Well said. I will have to look again at this and practice taking apart a few screens and replacing the backlights. This would bring my costs down and hopefully win me some more business.

Good luck Craig with the repair.

 

[CraiGDaniel]

New invertor good as new!


Funny how the bloke i bought the laptop off said the shop wanted £xxx to fix it as they had to order a part in from another country.

As i thought, just a new invertor. Bought it cheap as chips will make a nice profit selling it on.. thanks all!!

 

[Martyn]

If you got a new invertor for most of those faint screen problems your would be right in 99% of the cases in my experience.

 

[Rob_NNCC]

If you got a new invertor for most of those faint screen problems your would be right in 99% of the cases in my experience.

I fully agree, I have always purchased an inverter first, never have had to buy a new CFL.

 

[Upnorth]

I had the exact same symptom, bought a new inverter which was a small fortune as it was so rare only to find the same dark screen when fitted. After an hour of testing I found it was the inverter cable, had to be twisted a certain way to get the connection which I did by accident.
First and only time I've come across it, managed to sell the inverter on Ebay thank god.

 

[CraiGDaniel]

Ahhhg! Right - After testing the laptop for a while a problem has made itself known.

When the charger is plugged in for more than 10 minutes, i loose the invertor again. The screen goes back to how it was before i replaced the invertor.

Only difference is, if i press the power button it sleeps the laptop, and when it comes back on the screen is back to normal!


To clarify when the charger is plugged in, the invertor is dying after a while... ahhh any ideas? doesn't die under just battery,.