On 12/15/2015 8:08 PM, Jeff Liebermann wrote:
On 16 Dec 2015 03:21:01 GMT, Allodoxaphobia
wrote:

On Tue, 15 Dec 2015 17:47:13 -0800, Jeff Liebermann wrote:

However, it also helps to pay attention. Do you see a problem here?
http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg

Either the (out of focus) black capacitors are installed backwards
or the board is mis-labled with the "+" signs.
Jonesy

Yep, you got it. Electrolytic capacitors are identified by a wide
stripe on the negative end. To make it easy to hand insert
electrolytics, the PCB is usually silk screen with a wide white area
around the corresponding negative wire. Usually, except for this find
Dell motherboard, that marks the positive lead instead with a wide
white area. To their credit, they added "+" marks, which I missed.
Having replace plenty caps on boards where the negative terminal is
marked, I didn't think to look for the "+" sign, and so installed it
backwards. The computer actually ran for a day or so, before it
started acting funny and blew the tops open. I initially thought I
had a batch of bad caps, so I replaced them a 2nd time, inserting them
backwards again. I knew I was in trouble when the caps got rather
warm. In desperation, I posted the photo to this newsgroup and got an
instant response. Only then did I notice that the PCB silk screen
markings were backwards.

Like I said, it pays to pay attention when re-capping.




Oh...that was too obvious. Missed it!

John :-#(#

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