So awhile back my roommate said I could have one of his old monitors since its backlight was miffed.
I couldn't figure out a simple way to fix it.
It's an ASUS VS248H, and sometimes the backlight works perfectly fine, and most of the time it does shit like this.
Is there a free or cheap way to fix this? I mostly just want to fix it to sell it (not a fan of how it looks honestly)
Pic related
>>55244489
Backlight is obviously fucked. It's an edge-lit LED backlight, looks like it has four sections, three are opens.
Most likely: bad cable/connection attaching backlight to backlight controller.
Other possibilities: Shit you'll have no idea how to diagnose or fix.
>>55244521
Should I pop it open to see if theres a loose connection then?
And yea it doesn't all go out at once, spreads to those.
>>55244571
Do the others suddenly go out, flicker, dim slowly? Come to think of it, that will mean something.
[as for opening it... well, it's already broken. Mind the mains power and caps in the PSU]
>>55244585
Honestly I never actually noticed it happen as I rarely ever have it on. Or its just like that when I come back. I think they just go out. Might open her and see later.
>>55244617
then most likely a mechanical connection died. Connector, cable, maybe a broken solder joint in the backlight strip itself (since that will get hot and thermally cycle).
>>55244721
well the strip inside looks fine, fucked up the bezel a lil, gona look around at the board now.
>>55244936
a broken solder joint isn't going to be visually obvious... sometimes I can't even see them under a microscope.
right side became purple + vertical waves. any idea if this is fixable?
23" Dell UltraSharp U2312HM
>>55245018
True true, well this is like an adventure now.
Though I am at a standstill now. The control boards wont pull off the back shell.
>>55245055
got a constant current supply? You can test that LED bar before disassembling everything else (potentially unnecessarily--- my money is on the LED bar right now)
>>55245079
I could plug her back into a strip
Need to pop the panel back open but that aint no probelm
Keep posting OP, this is getting interesting.
>>55245195
working on popping it back open.
>>55245204
fucking hell wasnt ready for how bright these are/
>>55245257
is it working?
>>55245257
>>55245270
Alright since i obviously have it dismantled and the screen not actually plugged into my computer, I can get the LEDs to turn on and off, some work some don't. It's a continuous strip on a circuit board running along the bottom of the panel casing. Sometimes they all turn on, sometimes patches don't.
Shits too bright for a picture. They kind of flash on and off, but I'm guessing that's from it not being hooked up to anything but power, cause they don't flicker when it's on.
>>55245321
maybe the supply circuit for the strip is not providing enough/adequate voltage, and the leds that have a higher forward voltage dont light up sometimes (they are all in parallel, i think)
does changing the brightness level (on your OS) makes some of the leds that are powered on go "dead" before the others?
>this belongs on /diy/ btw
>>55245381
>this could go on /g/ as well
Like I said its not actually plugged into my desktop , give me a moment to try that.
>>55245450
>>55245381
Ok here's a pic of the lights, was able to get these to stay on some how, tho they aren't the ones usually on. and OFC i cant see fuck cause i got all the intermittent layers taken out. That and this light is blinding.
Original helpful anon here (who, coincidentally enough, makes backlight retrofit kits)
>>55245321
>maybe the supply circuit for the strip is not providing enough/adequate voltage
No.
You have a multi-segment LED strip, with each segment under independent current control. An open at any point causes the whole segment to go out.
Either you've got a bad joint on the strip (if it's flexi--- slee likely) or a bonding failure inside the LED package (distressingly common in chinese LEDs).
The fix to this is very simple. There's no need to repair the existing hardware, it's probably fucked. Just buy a cheap LCD monitor from goodwill and swap the backlights out. Some rigging will be needed, and you will need to wire the power into the components on your broken monitor but it will be perfectly functional. I have done this in the past with no issue
>>55245554
>The fix to this is very simple. There's no need to repair the existing hardware, it's probably fucked. Just buy a cheap LCD monitor from goodwill and swap the backlights out. Some rigging will be needed, and you will need to wire the power into the components on your broken monitor but it will be perfectly functional. I have done this in the past with no issue
"You've got an engine knock in your Chevy? Better buy a whole Ford and jury-rig that engine into it"
At worst, you've got three LEDs out. At best, you merely have three broken solder joints. A multimeter will tell you where the open is. Reflow the joints. If that doesn't fix it, replace just those LEDs.
>>55245552
ok so that last pic is with it actually displaying my desktop (missing the layers that make it easily visible of course).
Also its one continues PCB that the lights are attached to, not a flexible strip. Also seems bound to the rear casing.
>>55245554
>
>>55245581
Actually, one last possibility--- comes up in retrofits all the time, it would be weird if it was a problem in a manufactured panel---
you have an exposed solder joint or trace shorting against the metal channel the backlight is in. But if it still had segments out when removed from the channel, that's not it.
>>55245581
>Order chink shit LEDs from China for 15 dorras plus shipping
>Spend 5 or less burger bucks
Choice is yours OP. Alternatively, ask the manufacturer. Often they will send you parts for free
>>55245516
can you measure any voltage on the leds that are turned off (at start or stop of the off parts, measure from led leg to ground)? if there is voltage there then its either not enough to power the led of the led is busted (can crap out after overheating or over-voltage)
also, have you taken a look at the led driver pcb?
>>55245597
>Also its one continues PCB that the lights are attached to, not a flexible strip.
OK, good, makes things easier.
>Also seems bound to the rear casing.
Yeah, usually 'transfer adhesive', a really strong doublesticky tape that's really thin. Gently see if one side will pry away. The circuit board will be fairly flexible. FR4 is tough.
>>55245619
Sadly I don't have a multimeter or anything. The way the lights turn on and off is strange.
>>55245628
I'll see what i can do, don't really want to plug it back in right now, cause holy fuck my eyes hurt, even with sunglasses.
>>55245617
>>Order chink shit LEDs from China for 15 dorras plus shipping
>>Spend 5 or less burger bucks
>Choice is yours OP. Alternatively, ask the manufacturer. Often they will send you parts for free
So will I, but you should send me one off the strip first so I can match it. Backlight LEDs vary a lot.
>>55245634
>The way the lights turn on and off is strange.
? explain. could be relevant.
>>55245647
post pic of led driver board pls
>>55245647
>>55245634
hell, the PCB looks like its STUCK on there, as in if I try to pry it off it'll snap. It's thin, narrow, and almost flush.
Also the LEDs will sometimes all turn on, sometimes sections turn on, sometimes flash, sometimes just the ones you see on. Whats oddest is that the one that usually stays on when this is assembled and connected is off as well in that picture what stability I could achieve.
>>55245662
Here's the only identification I could find. Otherwise it's just a strip with each led labeled as Dxx
>>55245721
not the led pcb, the driver one, the board where that one connects to (should contain a choke and some other components)
>>55245667
>Also the LEDs will sometimes all turn on, sometimes sections turn on, sometimes flash, sometimes just the ones you see on. Whats oddest is that the one that usually stays on when this is assembled and connected is off as well in that picture what stability I could achieve.
Ah, and you didn't try powering them from a power supply without the driver board.
Flickering, turning on and off, etc, is actually pretty typical of a diode with a junction failure. Very common in first generations of Chinese InGaN LEDs. Think 'Green stoplights with half the LEDs out or flickering' syndrome. Or it could still be the driver or some other failure. Thus the desire to divide the problem in half by testing the strip on a power supply.
Anyway, it sounds like you don't really have the tools to go any further.
>>55245747
>>55245747
One board
>>55245826
>>55245747
Other board
>>55245812
Sadly this seems more like the case. Not economically viable right now to buy the tools to go any further. Though like I said, when plugged in, the lights all stay on, then eventually just the one in my OP stays lit (talking purely about when it's hooked up on my desk)
>>55245854
yeah, could still easily be driver board-- but that will be even harder to debug. If you don't even have a multimeter, you're likely screwed.
>>55245842
that top left ribbon/cable goes to the led pcb right? dont see anything wrong with those btw
>>55245854
wait a sec, so when its cold all the leds power on (no flicker) then after some time some start to flicker and then only one section stays lit?
if so get a el cheapo multimeter from the dolar store and find the culprit led!
>>55245903
he'd still need to find a matching LED. I don't have any in that particular package.
>>55245903
Top left goes to the other end of >>55245721 to power the lights, and the middle right connects to >>55245826
Also like you turn it on (since connections arent the tightest fucking around in my cluttered room) and those lights will all come on, since you cant really see shit, you flip around using the input button until you get the actual PC output so it'll stay on rather than trying to sleep. Once that happens only the ones that you see on in >>55245516 stay on.
However, if you let it sit for a long time (like I had) all of them work again, until eventually you reach >>55244489
>>55245903
But he can get a piece of wire and put one end on one working Led and the other end of the wire on the not working leds.... (Just make a bridge)
>>55245963
Yes, he could do that (and current regulation would keep the others in spec). You'll have a dim spot there in the display, but it won't be... as bad.
>>55245963
>>55245972
Also, if a few have failed, I'd expect several others to be ready to go in short order as well :-(
>>55245987
Well like I said (OP) the lights aren't burnt out.
>>55245996
LEDs don't burn out. They either slowly fade (due to package degrdation and electromigration) or the fail (bonding failure, junction fracture/delamination failure). You're seeing something that would be explained by junction failure. Most LEDs fail as intermittent opens.
>>55246035
Huh, learned something new today.
Since it seems I can't really do much from here I will say thank you to all of you for helping. Might see if I can't get a cheap MM from somewhere.
If I do should I check each segment or what?
What should I Look for etc etc etc
>>55246077
You can take a couple of AA batteries in series to get 3V and test the leds one by one. The one that wont lit is the culprit
>>55245924
i was thinking about >>55245963 but that just hit me. package is not that important, the lumens and forwards voltage though
>>55246077
$5 multimeter have diode/continuity test, should supply enough voltage and milliamperes to power the led
if anything else, you get an additional tool for another rainy day
>>55246129
?
When the entire strip is on, all the LEDs are on, not a single one is out. It splits into quarters, so should I test each individual LED then? also just take some wires to a AAs and put them where? I wasnt able to lift the board off, much less where it's plugged into.
>>55246137
oh, yeah, for testing, right. Yeah, that's a good idea.
>>55246167
Wait, you can get all the leds to turn on?
>>55246175
forward voltage doesn't matter (thy're in series and carrying the same current). Lumens and color does matter (not all whites are the same). And for testing you can find the open by bridging with a wire like the other anon said.
Package matters a little (for heat dissipation).
>>55246181
I mean, at the same time
>>55246181
I've said it multiple times, yes.
They won't all stay on though, as I said earlier they turn off in sections over time. Even dicking around with buttons while plugged in will sometimes cause them all to flash once or turn on randomly (in sections).
My dad bought the same monitor. Does the exact same shit. I warned him from buying refurbs but he didn't listen. Meanwhile the Korean monitors I bought for the same price still work great.
>>55246211
Lol I'm using a fairly new Dell and one I found laying around outside from like 2003, both work fine. This was my roommate's.
>>55246211
>>55246195
>>55246193
>>55246191
But yeah, wire bridge should determine 'LED fail' or 'driver fail'
>>55246195
Ok, i'm dammn sure you have a broken solder joint somewhere in that pcb.
>>55246240
So it's pretty much fucked.
>>55246167
test each led on the parts that stay off after some time (4 section and one stays on right?)
once you have found a led that has continuity issues bridge it with something and see if that strip section light up, if it does, move onto the next section that stays off. repeat until all sections work
then comes the hard task of finding matching leds (that is if you dont mind some dim spots, should not be very visible at near full brightness)
gl
>>55246285
like desolder the old LEDs and simply replace them?
At this point im considering scrapping it on ebay or just tossing most of it.
>>55245034
Have you tried to run the LCD conditioning? That's a dell thing, I don't know how you can enable it.
>>55246309
>Have you tried to run the LCD conditioning? That's a dell thing, I don't know how you can enable it.
maybe he could just paint the whole thing red. That could totally work, right?
>>55246285
ps: use multimeter with no power on the strip power, connect power to check strips
or do as >>55246237 said, bridge each one till you see the section light up (if its more then one it will take some time this way)
>>55246300
yeah, or you can just leave it with the patches over the offending leds, shouldnt be too noticeable (unless there is a bunch of them)
>>55246316
Depends. If it is purple-ish, that means the green isn't working, but the vertical lines are usually found on the red ones.
>>55246351
The pic in the OP is how it always ends up looking so itd be a lot of leds.
>>55244489
My main monitor's cfls died so im replacing them with leds. Cfls are too damn expensive nowdays
>>55246362
not necessarily, each section has leds in series (eg. D70 to D8X) but each section is in parallel with each other. so one bad led in one section will make that whole section of 10+ leds stop working (while the other section continue to work)
its a gamble though, still better than tossing a working monitor over backlight issues (ebay probably has backlight led strips for some pennies, op would need to acquir another a led driver board though, that means no OSD brightness control)
>>55246392
I'll have to look around then. Thanks again, anons. Nice to see this place not be shit occasionally.
>>55246383
And less efficient and less bright and shorter-lived. That's why I make retrofit kits for old ThinkPads.
>>55244489
I also have a LG monitor that does the exact same thing in both bottom corners.
>>55246392
>ebay probably has backlight led strips for some pennies
they do, and they're not worth buying. Eg, if you want your monitor to always look kinda greenish yellow...
>>55246531
when I looked up >>55245721 I got LG boards as well.
>>55246309
didn't work. thanks tho
