Dell monitor Backlighting goes out after a few moments

[Warlock79]

I have a Dell 23inch monitor that my uncle brought to me to try and fix ,

it powers up lights up for a moment then the backlighting takes a dump.

I did a self test on it , but it doesn't stay on long enough to complete it ,,,

I shined a light into the monitor and saw the images were still loading so the screen it self is working.

SO I'm assuming it is the backlighting, I have it apart now looking over the inverter board.

First thing I checked was buldges on the capacitors they look pretty much factory new condition no buldges.

looked over soldering joints on the Caps doesnt appear to be anything wrong there.

was gonna see if the on board fuse was bad but I mean if the fuse was bad the thing wouldnt power up at all.

could it still be the capacitor?

the main cap looks fine but if it helps the cap is an elite 120uf 450V
I heard elite isnt so great of a cap brand so if its that I can replace it i just need to find a replacement for it.

if anyone has any other suggestions on whats up with it I would appreciate the advice.

 

[Shaun o]

There are two places to look for a bad cap or signs of a bad one.
Most people look at the top side, but on slightly older ones without a lined cross on the top. the bottom of the capacitor must also be checked for doming.

The cross on new models of capacitors was created to produce a weak spot where it would be prominent the cap was on it`s way out.

What looks like a good cap visually is often not the case an should in fact be tested by a capacitor multi meter.
The main cause is down to the set or buch of caps located just off the main power section of the board.
Where one will provide power to the inverters of the board, and the other set provide power to the decoder chip, and display control.

 

[drtweak]

Yea shaun o said it perfectly. Now when it turns off, if you take a flash light to it, can you still see your desktop? If so then its just some bad capacitors that you can usually find in a kit that is sold on eBay or Amazon. Me because i fix stuff like this on a weekly basis i always have a vareity of caps laying around and I only use high end japanesse caps. http://www.badcaps.net/ can tell you and show you a lot and for the most part stick with Nichicon Nippon Panasonic Rubycon Sanyo brand Caps. They are the good brands.

 

[Warlock79]

this cap has the weak point crosses ontop very plain as day ,, as do all the caps what i may do is jot down all the caps info and just replace them all to be on the safe side. was wondering if there was another possibility for this issue , oh and yes shined a flashlight into it and saw the desktop so yeah it is working .