Dell - ST2410 - Flickering screen light and dark

[SkeeterUK]

Posted my problem in the New Members thread so ill just copy it to here.

Hi im SkeeterUK. From the UK. I have registered with the site in hopes of some assistance with monitor repair.

I have a dell st2410 monitor. It was flickering on the brightness. I suspected the cfl bulbs but was then told it could be bad caps inside. With it being unusable my monitor i thought why not and open it up to see if there was any.

http://s1374.photobucket.com/user/Sk...slideshow/caps

As you can see there wasnt but no buldging doesnt auto mean not a bad cap. I dont have a multimeter i dont know squat about electrics tho im good at pcs and building em. Anyhow, if it was bad caps i was gona get my cuson to solder new ones in if i could find out what caps was needed. Anyhow as pics, i duno if its caps afterall.

Problem was, pink hue in the bottom left corner of the screen when viewing a all white screen like notepad open. When starting monitor it was all pink near the bottom not as bad on the top half but went away after 15 secs. This is from a cold boot. Later as of today. It was flickering light and dark. It wasnt too bad, then it stayed on longer and flickered more. Then once today it went black as if turned off (duno if it did turn in to standby or not cant recall color on power button) then came on about half a min later or somit.

Anyhow, i cant post a new topic it seems, so any help would be appreciated.

I had tried the 2 self tests dell told me without any cable in for the computer, still flickered, also tried vga and dvi cable both connecting to either onboard or dedicated gpu, still flickered. Was so bad i thought why not look at caps on it as someone at a different forum suggested it might be.

[selldoor]

Re: Dell - ST2410 - Flickering screen light and dark

Can you post good clear pictures of the power supply and main board
Looking straight on , top and bottom. Post them using manage attachments
jpg less then 3mb work ok.
Pink tint suggests a faulty bulb as does flickering. Has it got many hours on it?

[SkeeterUK]

Re: Dell - ST2410 - Flickering screen light and dark

Darn, ive put it back together now as i thought the pics in the link would have been enough.

[selldoor]

Re: Dell - ST2410 - Flickering screen light and dark

Well, if it is bulbs you will need it in even more bits.

[SkeeterUK]

Re: Dell - ST2410 - Flickering screen light and dark

I did try to access the bulbs but the thin frame bits around the actual lcd display was nerve racking so i stopped when i got up to a point where i thought hmm can i put this back together after i do this next bit...

Little bit too far out of my comfort zone. The caps i might have managed with help from cuson to do the soldering but changing the bulbs i dont know if i can do it.

[selldoor]

Re: Dell - ST2410 - Flickering screen light and dark

Ok - you may want to part it out then or sell as fault or try and buy one with
a power supply fault.
Something to try as you say the pink is predominantly at the bottom is
to swap the leads to the bulbs over - That was one reason for the pics
cant see them, anyway assume there are two one is usually for the top bulbs
and one for the bottom so if you can swap them the pink should go to the top.
If not then we can look elsewhere.

Interesting to see two dells with a similar problem on here at the same time.

[SkeeterUK]

Re: Dell - ST2410 - Flickering screen light and dark

Hmm link works for me, ah well here you are. Pics.

[selldoor]

Re: Dell - ST2410 - Flickering screen light and dark

page doesnt exist that is the reason we ask for them to be posted using manage attachments

[SkeeterUK]

Re: Dell - ST2410 - Flickering screen light and dark

Pics updated in previous post.

[selldoor]

Re: Dell - ST2410 - Flickering screen light and dark

Ok - talking at cross purpose, but thanks for those pictures - I was trying to say I cant see any
connectors for the lamps in the pictures not that I couldnt see the pictures.

Anyway assume there are two one is usually for the top bulbs
and one for the bottom so if you can swap them the pink tinge should go to the top
confirming a bulb problem.
If not then we can look elsewhere.

[chozo4]

Re: Dell - ST2410 - Flickering screen light and dark

hmm, it could be a bad solder joint too. Inspect every solder joint closely on the through-hole components for a small hairline break around where the joints are soldered if there are any at all. Symptoms such as this can show poor functionality until the heat cycles causing on/off or variations thereof.

Just fixed a TV for a friend that wouldn't power on the screen at all and would exhibit power supply clicking. Was a bad solder joint at one of the transistors collector and fired right up upon fixing it.

This has some good examples on how to spot such a joint.
How to spot a dry joint, (fixing relay units or ecu)
http://mercedes-190.co.uk/topic/6581171/1/

and a video demonstrating it:
https://www.youtube.com/watch?v=9VYA9ufb4Jc

[SkeeterUK]

Re: Dell - ST2410 - Flickering screen light and dark

I tapped the top corner of the screen when testing the self test colors when dissasembled and the flicker went away. So i put it back together, it lasted about 3-4 hours and then the screen went off and wont stay on. When the screen is turned on it flashes up like its ok then immediatly goes black but i can see a faint image of it working as when i press the start button i can just about make out the menu pop up that comes with clicking on start button.

Swear tho that when i looked at the caps they were fine lookin and not buldging. What could it be, caps bad but looks fine? a transistor of sorts? inverter whatever that is?

[budm]

Re: Dell - ST2410 - Flickering screen light and dark

These st series is cost cutting design using just 2 lamps instead of 4 lamps so the lamps are driven hard and they just fail. They are just bad series, only 2 lamps for 22" and 24".
This the 22" version:
http://s807.photobucket.com/user/bud...?sort=3&page=1

https://www.badcaps.net/forum/showthread.php?t=39282

[Lumberjack777]

Re: Dell - ST2410 - Flickering screen light and dark

Something to try as you say the pink is predominantly at the bottom is
to swap the leads to the bulbs over - That was one reason for the pics
cant see them, anyway assume there are two one is usually for the top bulbs
and one for the bottom so if you can swap them the pink should go to the top.

That was a very good point selldoor made. A pinkish hue on a white screen is almost always a CCFL (bulb) that is going bad. By swapping top and bottom connections the pink hue would move to the top and you'd know for sure.

I don't think this is a cap problem. I think its a bulb problem. You'll need to get a set of test bulbs, or make some.

EDIT: I see you still type faster budm. Glad to see we came to the same conclusion

[SkeeterUK]

Re: Dell - ST2410 - Flickering screen light and dark

I tried awhile ago see if they could be switched the cables for the bulbs, but while one would go in the other one the other one couldnt reach the other port so no it wouldnt work as one cable was too small.

[selldoor]

Re: Dell - ST2410 - Flickering screen light and dark

Well its probably too late now if the bulb was bad tapping it will have finished it off possibly
taking the inverter with it. Best option now would be to make up two of Budms test lamps
from household cfls and try with those. Instructions are in Budms signature on th ebottom of most of his first posts in any thread.

[SkeeterUK]

Re: Dell - ST2410 - Flickering screen light and dark

Thanks for your replies but i think its too far gone for me to mess with now, saw a £20 acer 22" x223HQ so got that today, it works, will do till i can afford a decent one once again.

Again cheers for replying.

[selldoor]

Re: Dell - ST2410 - Flickering screen light and dark

Perhaps you can sell it for spares/repairs whatever dont throw it away -offer it on
freecycle or freegle - id have had a go at it if it was in my area.
Some Acers are also prone to bad bulbs - in search above type in the model and see if anything comes up.

[techgirl107]

Re: Dell - ST2410 - Flickering screen light and dark

I'm looking to fix a Dell st2410b for a friend and in need of an IC. It's located in the top left hand corner of the main board. It has four capacitors around it. I have tested this part and it is bad. The only thing is, I can't locate this part from the numbers on it anywhere on the net. It looks like some kind of IC regulator. If someone knows exactly what part this is, it would be greatly appreciated if you would let me know.

Thanks

[Lumberjack777]

Re: Dell - ST2410 - Flickering screen light and dark

If you could attach a nice closeup picture that would help a lot. I'm a little curious how you could test it unless you know what the part is. If it's a voltage regulator you'll need to know if its fixed or adjustable. Also, the capacitors nearby can go bad and never show any outward signs. If you could get us a nice closeup we might be able to identify the IC, and/or isolate the problem.