My family owns a pc repair shop and someone dropped off a dead Korean monitor. 2560x1600 resolution, 30 inch. I cracked it open to try and fix it, and after a while I finally found what appears to be a blown resistor?
I'm looking for a heatgun so I can replace it, but I have no idea what the value of the resistor is.
Beside it, it says 24v 403, I'm assuming that means it's 24 volts, and that 403 is the identifier for the resistance of the resistor?
Pic related, thanks in advance for any help.
>>1002714
Here's a pic with a torch instead of flash, it looks clearer but has shadows.
>>1002715
That looks like an inductor not a resistor(note the L403). Also usually resistors in SMD packages have their resistance printed on top. The best thing to do right now is to find a service manual that actually has a schematic in it and find the exact value of this part. Failing that you could remove it and measure but if it has really blown you won't get something meaningful.
>>1002714
Since it's L403, it's much more likely a ferrite bead.
Ferrite beads generally have no markings, but the replacement isn't probably critical and even a piece of wire is likely to work (even if it won't fulfill the legal requirements for emissions).
The thing is that ferrite beads do not fail on their own. You either have a short circuit downstream or the stuff before the bead is fucked.
>>1002718
I won't be back there until Monday, but I'll try replacing it with a wire to see if it works. Just closed up 10 minutes ago.
Is there a risk of it not functioning properly if I just use a wire? Does wire gauge matter?
>>1002717
Fuck I hope nothing else is damaged. The other boards looked fine though, could it be the power supply? It has an external brick like a laptop charger.
I should add, when I plugged it in, the power led came on green, then started blinking red after a few minutes, probably going into sleep mode.
Wouldn't detect any input at all, and no image on the screen at all.
>>1002720
>Is there a risk of it not functioning properly if I just use a wire?
Certainly, if my guess was wrong and it actually wasn't a ferrite bead. Otherwise it's quite unlikely.
>Does wire gauge matter?
As long as it isn't overly thin, no.
Well, if you're lucky, it was just soldered badly and that's why it burned. I wouldn't count on that, though.
>>1002729
Thanks anon, I'll give it a try anyways since its already broken.
>>1002718
what he said.
Inductors are non critical components (usually) and probably something else made it blow.
>>1003284
Would changing the inductor fix the issue? Or should I just give up?
It's a $450 monitor, so I'd love it if I could fix it.
>>1002718
Confirmed. L402 and L403 are the reference designators, and only one of the two components is populated there because only one of the two voltage options is selected; I'm guessing you have a 24v supply that you are plugging it in to.
Anyway as anon said. It is a ferrite bead, and the value isn't critical. You probably can make it work by just soldering a piece of wire across it. All it is doing is filtering high frequency out of the input power.
Also mentioned here is that this component being blown indicates another problem. Specifically, since this thing obviously burned, it's a sign that you have a short circuit downstream that was pulling a lot of current, and this component was the weakest link that blew first. I would recommend testing for a short circuit between +24v and ground.
>>1003305
So the power brick then?
>you could even replace it with a blob of solder
Thoughts?
I want to get it working but I don't want it blowing up somewhere else. It's my only chance at a 1440p Korean monitor since I'd never spend that kind of money on my pc.
http://electronics.stackexchange.com/questions/206423/possible-to-identify-burnt-component-and-its-value
>>1003312
No, more like a polarized capacitor on the circuit board somewhere. Big aluminum caps get used to filter power, and I would start with that. It could also easily be a diode somewhere on the board. Check to see if any of them are shorted. Next most likely thing is a burned up chip or transistor that has an internal short between power and ground.
You should be able to tell if there is a short between +24v and ground just by measuring between where that burned out fb is and any ground point; if it's low resistance there is a short somewhere, then you just have to find it.
>>1003316
Thanks anon. I'll test it with my multimeter.
Won't have access to it for another 2 days though.
>>1003333
while we're waiting for op and his multimeter i wanted to bring in a slightly different concern instead of opening the third tftmonitor thread on diy.
>purchase 24" monitor on a fleamarket for 25 eur
>guy who sold it says menu buttons are broken, on/off works, panel works
>no input signal available to test but the thing powers on, lights on
>"oh-what-a-diy-bargain"
>at home it turns out the thing only schows pic related and goes to standby mode after some time
>if inputsignal (no matter if hdmi or vga) the thing stays on like in the pic
>computer recognizes the monitor correctly
is there any chance of getting this thing fixed and if not wut to do with a bluscreen like that?
>>1004046
If the problem is in the signal channel best thing to do is buy another with a broken panel off ebay for 10 bucks and panel swap. Fault tracking without a service manual is not worth it. Even with a service manual (if one even exists) the factory would just do a components test and swap out the entire signal board. It simply isn't worth the time to diagnose circuit level problems.
>>1004077
well i assumed it's the signalboard.nit's hard to reach and i wont take the whole thing apart again so have this shitty drawing: instead of a detatchable cable between signalboard and panel it seems the board is directly connected via flexcables to the panel. so your suggestion of swapping the signal board wont work that easily.
>>1004149
Are you saying that the signal input processor, main board, and lcd driver board are all on the same board that is hard wired through flex cables to the actual lcd panel? That would be incredibly stupid design. I've never seen a panel directly soldered to the driver board. If that's the case RIP your time or your money. You choose.
>>1004152
I also saw this kind of design for the first time. And after reading your post i took it apart. any parts worth to salvage/reuse for something else?
>>1002715
It doesn't look like it's part of the buck circuit, so you're probably good to replace it with some random value inductor until it works right.
The only inductor the buck circuit needs is that big square one with 330 written on it. If the blown inductor is related to the buck converter it's probably just for extra smoothing or something so you can probably just replace it. You could honestly probably just put a jumper across it and it would work.
I'm reading this on my phone, and the first time I see this thread, I read
'someone drops off a dead Korean'
Horrified
>>1004162
Are those flex cables wave soldered or just glued? They look like the glued kind. Pic is too blurry to tell. If they're glued carefully try to pry them off with an exacto knife. If you get them up proceed to the ebay step.
Only things worth salvaging is the panel and PSU. It might be worth it to check the PSU and make sure the rails are in spec. Maybe the problem is something simple.
>>1004398
You should be able to heat the connectors with a hair dryer and reactive the glue on them. Otherwise look up, "anisotropic conductive film."
>>1002714
Did you try turning it off and back on again?
>>1002714
Here's hoping it works.
>inb4 shit solder job
I left my good soldering iron at home.
>>1004796
At least this time the screen comes on, but it doesn't detect any input.
>>1004796
Is it just me or does the buck converter (middle center, 1501-33) look kinda melty?
>>1004809
yeah definitely. when the silicon melts down it makes a lump on the plastic casing.
>>1004810
So that could be damaged?
>>1004816
Just a thought though, if it had melted, wouldn't the writing also have been affected?
>>1004818
Yup, Just cleaned it with meth and the "melty" marks are gone.
check with different connectors ex (hdmi, vga, displayport)
>>1004852
I did. It worked with HDMI, but not vga or dvi.
Thanks for the help anons, I think I'll just use it as is is. The IPS display looks lovely.
>>1004796
>butchering someone elses electronics
>implying a better soldering iron would fix your incompetence
I am horrified.
>>1004895
It was a horrible soldering iron. It would barely get hot enough to melt the solder...
>>1004907
It was hot enough, the tip wasn't tinned.
>>1004910
Regardless of how bad and unprofessional it may be, it works, and I added hot glue in case it comes off.
It's sealed up and working fine on hdmi. Good enough.
>>1004913
>I added hot glue
>>1004937
What's wrong with that? It's secure and easy to remove if I ever need to remove it.
>>1005258
I like you.
>>1004937
Its Drakon the NES modder!
>>1005292
It genuinely works well. I honestly can't complain.
Good on you OP. I had a PCBank PB 2700 (one of the first gens) for nearly four years before the PSU finally went. The insides had also corroded a bit though, might've been the radiator in my room.
It's amazing how little shit like a blown cap can just completely fuck up a monitor but be easily replaceable.
