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bad Capacitors on PC motherboard - repair without re-soldering?

bad Capacitors on PC motherboard - repair without re-soldering?

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  #1  
Old 10-28-19, 10:46 AM
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bad Capacitors on PC motherboard - repair without re-soldering?

Has anybody tried replacing small (pencil eraser sized) capacitors on a motherboard / control board by cutting/crushing and removing the electrolyte drum, while leaving the tabs soldered to the board, then connecting the replacement capacitor to the old tabs, using car-stereo butt-crimp splices?

Instead of disassembling everything and doing the fiddly soldering, it occurred to me that removing a bad capacitor but leaving the leads soldered in, would be much easier.



The specific application is an old Dell Precision 390 with bad/swelling capacitors, not an uncommon problem when the computer was assembled, https://en.wikipedia.org/wiki/Capacitor_plague

There is easy access to the capacitors from the TOP, (a photos from somebody else's 390 shows the easy access to the bad capacitors-



So, anybody ever tried an "in-line splice" for something as small as a capacitor?
 

Last edited by Hal_S; 10-28-19 at 12:22 PM.
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  #2  
Old 10-28-19, 10:49 AM
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I've never found through hole components to be difficult to remove so I always desolder caps from the board and replace them properly. If you're going to try your crunching apart a cap idea I would try a test first. I have no idea what the leads are like inside the cap to know how easy it would be to solder to them.
 
  #3  
Old 10-28-19, 12:06 PM
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I have no idea what the leads are like inside the cap to know how easy it would be to solder to them.
Actually, since the replacements are long-lead capacitors

I wasn't planning on soldering the leads,
Instead I was thinking of using car-stereo style butt crimp splices (24-awg) to make the connections. (went back and edited that into the initial post)

Process would be:
1) cut/crush the bad capacitor and remove it while leaving the soldered leads sticking up
2) slide butt crimp splice connectors down the still-soldered leads,
3) overlap leads of replacement capacitor with soldered leads
4) crimp the butt splice in place.

This seems a bit unorthodox, but with older computer equipment, I find that when you plug and unplug all those motherboard connectors, and you bend and re-bend old wires, it can create new problems by breaking-stretching-moving old wires.
 

Last edited by Hal_S; 10-28-19 at 12:23 PM.
  #4  
Old 10-28-19, 12:43 PM
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I've replaced hundreds of caps but always with board in hand. The only other idea might be to identify the circuit paths for that cap and if they come top side where you can solder the replacement to a land of exposed component lead it could eliminate the crimp.

I've also never cut one apart but many have leaked whatever is inside and caused problems on the board.

In addition, when a cap fails it usually involves heat which may have created a poor solder connection on the bottom.

As for plugging and unplugging connectors that could also eliminate related problems.

Bud
 
  #5  
Old 10-28-19, 12:56 PM
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Yes the capacitor will not be easy to take apart, it is a metal can.
I have never seen crimp connectors small enough for this size of wire.
Also how are you going to get a crimper in there.

So for the reasons above and others I have not listed I doubt very much that this will work.
 
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