[SOLVED] What is this Motherboard Component?

Jan 25, 2021
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So, my son and I updated an old Dell Vostro 460 computer with a marginally better video card and some extra RAM a couple years back so he could play Subnautica, and we were very excited that we got the game working, but then after a year a year or so, it just stopped. First I replaced the CPU, after doing a jumper test on it and it failed, but when I installed the new one, and turned it on, the fan would turn for a second, then stop, then turn again, then stop. I tried removing each component one by one to see if any of them were creating the problem, and nothing changed. I was obsessing. I scanned over the motherboard a few times with a magnifying glass, and I finally found something that looks like a damaged component, but I don't know how to figure out what it is. I am not a computer guy, but I want to try to replace this component on my own with my very old soldering skills. Assuming this is the component that has caused the computer to stop working, how do I figure out what it is and where to get it? I know this is a very old and weak computer, but now it's personal. I posted a close-up picture I found of the same motherboard online and and put an arrow pointing at it, and then a pic of my motherboard with an arrow to show where it is. It's supposed to be a solid black square, but on my computer, it looks like the black plastic has partly disintegrated and there is exposed, coiled wire. With the magnifying glass, I think there is a 49 beside the component. I'd love some wisdom. Thanks!

My Motherboard
The Component
 
Solution
I think i've tapped out my abilities, then. I've tested and replaced PSU and reset CMOS. The PSU just goes into a short cycle of on and off, so I get nothing on a screen at all to try to reflash the BIOS, which I think would be necessary? I've been over the motherboard with a magnifying glass a few times and the inductor is the only damaged component I've been able to identify, so I think I'm out of luck if replacing it won't do the trick. I appreciate the feedback, though.

Try turning it on with the CPU power connector disconnected, the GPU removed ( I assume it is discrete) and memory removed. If the PSU stops short cycling (it still won't work, of course) that will be a fair indication it's with the CPU or it's VRM, the GPU...
Hard to tell exactly but I believe that to be an inductor. I'm saying that mainly by elimination as it's size and shape doesn't fit that of most any other component...but also because it looks to have a reference designator beside it of 'L49'. An 'L' ref-des in usually refers to an inductor.

Inductors are very rare to fail in service because of their simplicity; it's just a few turns of wire inside and around a ferrite core (sintered powdered metal oxides). Some are made with exposed wire turns, some have the ferrite fully enclosing the wire. Make sure the core is cracked and damaged and it's not just part of it's construction.

Also, L49 in that picture looks to be surface mounted. That's not going to be easy to replace without a hot air reflow station.
 
Jan 25, 2021
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Hard to tell exactly but I believe that to be an inductor. I'm saying that mainly by elimination as it's size and shape doesn't fit that of most any other component...but also because it looks to have a reference designator beside it of 'L49'. An 'L' ref-des in usually refers to an inductor.

Inductors are very rare to fail in service because of their simplicity; it's just a few turns of wire inside and around a ferrite core (sintered powdered metal oxides). Some are made with exposed wire turns, some have the ferrite fully enclosing the wire. Make sure the core is cracked and damaged and it's not just part of it's construction.

Also, L49 in that picture looks to be surface mounted. That's not going to be easy to replace without a hot air reflow station.
Yes! there is an L before it. That is exactly the component. thanks. Is it reasonable to believe that if it is replaced correctly that it will fix the problem, or does the fact that it is damaged suggest that another component down the line has also been damaged?
 
Yes! there is an L before it. That is exactly the component. thanks. Is it reasonable to believe that if it is replaced correctly that it will fix the problem, or does the fact that it is damaged suggest that another component down the line has also been damaged?
It's very difficult to say if it will allow the board to work; it depends on what circuit it's in. It's a very small inductor and probably used for filtering...which is logical considering it's located in an area where most motherboards have the audio circuitry. But that's not usually going to prevent the board from operating at all, just not operating properly. It being broken also won't likely damage anything else; unless it's in a DC filtering circuit and the wire inside springs out and contacts a ground. But that's going to be really obvious and kind of a stretch.

Inductors are very simple things and simply never actually fail in service but can be damaged by something hitting it. That could also break loose the solder joint to the board. You might check that by pushing on it with a finger or a piece of plastic to see if it comes to life. If it does then all you need is to reflow the solder joint and make it work.
 
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L49 is one of voltage regulator inductors. In that photo look fine for me. They usually does not burn. If it would be visibly fried then your board would have damage elsewhere and visible without magnifying glass. I'm not sure that problem is caused by damaged electronics at all. Better start with PSU, then CMOS settings reset. Then check if board can load BIOS at all. Those serial flash memory chips sometimes screw themselves and require BIOS reflashing. And only then if it is not BIOS, begin to search for damaged components, starting with presence of all requiring voltages.
 
Jan 25, 2021
3
0
10
L49 is one of voltage regulator inductors. In that photo look fine for me. They usually does not burn. If it would be visibly fried then your board would have damage elsewhere and visible without magnifying glass. I'm not sure that problem is caused by damaged electronics at all. Better start with PSU, then CMOS settings reset. Then check if board can load BIOS at all. Those serial flash memory chips sometimes screw themselves and require BIOS reflashing. And only then if it is not BIOS, begin to search for damaged components, starting with presence of all requiring voltages.
I think i've tapped out my abilities, then. I've tested and replaced PSU and reset CMOS. The PSU just goes into a short cycle of on and off, so I get nothing on a screen at all to try to reflash the BIOS, which I think would be necessary? I've been over the motherboard with a magnifying glass a few times and the inductor is the only damaged component I've been able to identify, so I think I'm out of luck if replacing it won't do the trick. I appreciate the feedback, though.
 
I think i've tapped out my abilities, then. I've tested and replaced PSU and reset CMOS. The PSU just goes into a short cycle of on and off, so I get nothing on a screen at all to try to reflash the BIOS, which I think would be necessary? I've been over the motherboard with a magnifying glass a few times and the inductor is the only damaged component I've been able to identify, so I think I'm out of luck if replacing it won't do the trick. I appreciate the feedback, though.

Try turning it on with the CPU power connector disconnected, the GPU removed ( I assume it is discrete) and memory removed. If the PSU stops short cycling (it still won't work, of course) that will be a fair indication it's with the CPU or it's VRM, the GPU or the memory. Reconnect the CPU power connector then take the CPU out to isolate between those two; likewise plug in GPU and memory one by one and test till it starts short-cycling again.

I'm assuming you did the paper-clip test for the PSU. If so that's not a load test; you have to put a load on the PSU to see if it can hold it. Have you substituted in a known good one to properly isolate that?

If you're at wits end with it and have decided to just trash bin it you can simply remove the coil you think bad. An inductor appears as a short to any DC voltage, so if it is indeed damaged and presenting a low impedance to a PSU voltage causing it to power cycle then cleanly removing it should make it stop. If it continues on as before you'll know the real problem is much deeper and probably beyond economic repair. If it does stop power cycling something's still not going to work right though...but that may not matter anyway.
 
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Solution