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Can I fix a missing capacitor by just soldering the spot short? (lemmy.blahaj.zone)

submitted 5 months ago by [email protected] to c/[email protected]

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So, I've got a laptop screen that's giving up on me. 2/3 of the screen runs alright but the 1/3 on the left edge is acting weird. Half of the broken section displays an image but the image smudged and weird, while the other half is just dead. I opened it up to see what's up and, lo and behold, a wee tiny capacitor is missing (I know it's a capacitor 'cause I looked of the board marking, C248).

Now I'm wondering, since ordering a single capacitor just for fixing this screen is not worth the effort, can I just... put some solder in there to at least get power to where it needs to go? I know it's definitely not ideal but, this is an ancient laptop. Putting in the effort to fix it perfectly is not exactly a great value proposition. What I want to know most is, will the screen be damaged if I do this, or what could go wrong if I do this?

I'm pretty new to DIY electronics fixing so sorry if this is a stupid question. Thanks in advance y'all. Cheers!

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[–] [email protected] 25 points 5 months ago (2 children)

No, you can't short the pads. If there's no capacitor there then there likely never was unless you can see obvious damage. Not all components are placed when manufacturing. A picture would help but it could be a decoupling capacitor which has been deemed unnecessary or not required for the model. So it's unlikely to be the issue. It could still be other capacitors that are getting old but it would be the electrolytic ones.

[–] [email protected] 12 points 5 months ago* (last edited 5 months ago) (1 children)

I'm confident it's that capacitor since I can see the pads aren't rounded but jagged (there are rounded ones on the board, and I know those are supposed to be empty). That would suggest that the capacitor was torn off by the plastic of bevel of the display assembly being pushed in too far. I can also see that there's a hole in the protective tape covering board, right where the capacitor should be. It's a bit awkward to describe but yeah. Plus, the previous owner also described scratching that bevel and symptoms showing up after they did it too often. So all in all, I'm pretty sure it's the cap. Still, thank you for the answer!

[–] [email protected] 2 points 5 months ago

Okay, that certainly sounds like damage then. Most capacitors are pretty easy to solder and extremely cheap, you can buy them in small quantities. I would try a repair if you know what value capacitor