Capacitor replacement

[Orwellian]

My 4 yr old fell off the couch and landed on the wife's laptop (a cheap 3 yr old Dell) There was a slight crunch in the top left part of the base above the keyboard. Wouldn't get any power light, no boot, nothing. Checked power supply w/ meter and was gettin the DCv.

Took the laptop apart and noticed a capacitor had broken off the mobo up by the DC in. I manually held the capacitor onto the board and plugged in power. Viola, got power light and it started spinning up (basically just cpu since everything else was disconnected. I tried soldering the cap back onto the board, but didn't have enough lead coming out of cap to do a good job.

Question: its a 100 @ 25v cap, radio shack has only 35v. Is that kosher? I know on bigger AC stuff you can go higher voltage than original, but don't know about circuit board rules. Where the heck can I get a good replacement? I've noticed there are several different flavors of capacitors out there, and am not sure what the best one is.

Pretty much I know just enough about all this stuff to get me in trouble

 

[bruceb]

The 35V unit will work fine as long it will physically fit in the space available in the laptop.
Make 2 tiny loops in the wires coming from the pc board, then make tiny hooks on the new
capacitors leads. Crimp with needlenose pliers and solder .. position cap where it needs to be.
That should do it. Most cap makers now are pretty good .. Rubycon or Panasonic brands are
excellent and I am fairly sure what Radio Shack has is decent quality.

 

[RebateMonger]

Note that some capacitors on computer motherboards need to be "low ESR" models. These generate less heat at the high frequencies found on many motherboard locations. Low ESR capacitors are NOT something you'll find at Radio Shack.

Maybe you'll be fine. It depends on what that capcitor does and how hot it normally gets.

 

[bruceb]

Good point about the low ESR ... but this cap is at the DC power input jack and most laptop brick power supplies do not run at high frequencies, so it would not be an issue here. It would be an issue if the cap was inside a regular desk computer power supply as they do run at about 40Khz or so.

 

[Orwellian]

Excellent advice, many thanks to you both.

 

[Orwellian]

Thanks times 2, the capacitor replacement surgery was a resounding success. Little super glue to repair the crunched area, and everything works perfectly.