Req ID of capacitor

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  #1  
Old 02-14-16, 05:07 PM
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Question Req ID of capacitor

I have a visibly blown cap that I'd assume is identical to those very near it. Best I can figure they are 0.1uF 50V Axial Multilayer Ceramic Capacitors. The circuit is from a computer keyboard. ID appreciated.




The following are images of another board exhibiting the same exact problem but, as can be seen, is of different design. Visually I can see no failed component and there looks to be only one 104 cap. Figured I'd change that component out since I'll likely have to buy a mini bulk pack anyhow.



All insight appreciated.
 
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  #2  
Old 02-14-16, 08:03 PM
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Really...... C-2 actually exploded ? That's pretty strange. Those caps very rarely do that.
There can't be any more than 5vdc in the keyboard.

I would expect those caps to be used for debouncing on the keyboard strobe lines.
 
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Old 02-15-16, 12:59 AM
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Really ;-}. Aside from me lifting what's left of the leads just enough to read the rating nearly all the shell was "exploded". I've always taken the time to inspect faulty electronics in an attempt to spy failed caps, diodes, etc but I've only once ever found one (swollen electro cap).

I was given three used (and of unknown condition) DELL keyboards that I liked due to their compact format and while one worked the other two exhibited strange behavior and simply couldn't be used. Nearly all keys are non-functional with the exception of the space-bar, Delete, ESC, Tab and Caps Lock keys. As I enjoy tinkering, which is the only thing making an endeavor like this worth while, I figured why not give the caps a shot at fixing it.

So, the query remains... Am I in the right ballpark with 0.1uF 50V Axial Multilayer Ceramic Capacitors?
 
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Old 02-15-16, 01:04 AM
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I'll agree with the 104 is .1uf. The exact type of capacitor is unclear but where it is in that circuit I don't think it's super critical.

I would go with the ceramic caps that you mentioned.
 
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Old 02-15-16, 01:09 AM
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Thanks PJmax!

I'll give it a go then with those.
 
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Old 02-15-16, 12:38 PM
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One last question -- I know my need is for a .1uf and greater than 12v (to be safe, although most seem to start at 50v) cap but I have to wonder if "type" is specific. From what I understand type is basically a need factor of working environment and in lieu of that a cap is a cap, correct? I think I spied some non-polarized 104 ceramic disk caps on an old power supply I can thieve from if this is the case.
 
  #7  
Old 02-15-16, 06:22 PM
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That is 0.1uF axial ceramic capacitor.
You could replace with regular ceramic capacitor if there is enough room. (bit taller).

There will be some tolerance differences, but for this circuit, it shouldn't matter.
 
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Old 02-15-16, 07:40 PM
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Thanks lambition!

It's recycle time. ;-)
 
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