On Thu, 14 Feb 2013 10:29:13 -0500, wrote:

I have a Dell Optiplex SX260 small desktop type computer that won't
boot up.

Bulging capacitors on the motherboard. Probably nothing wrong with
the DA-1 external power supply, but it would a good idea to check if
you're getting 12VDC on the output. Also, put a scope on the 12V PS
output and look for noise. So far, I haven't found any bad power
supplies, but I've fixed about five of the SX260/270 boxes with bad
caps on the MB. It's not horribly difficult to replace the caps, but
it's tedious. Also, getting the motherboard out of the case is a bit
of a challenge around the rear panel green locking mechanism.

If you don't mind the shotgun approach, try a rebuild kit.
http://www.thecapking.com/sx260.html
http://www.ebay.com/itm/290339293027
http://www.ebay.com/itm/130683253583
etc...

Hint: The fastest CPU that will work in the SX260 is 2.8GHz with
hyperthreading.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558