On Sunday, November 20, 2016 at 2:49:41 PM UTC-5, wrote:
I have a Samlex 120VAC-13.5VDC at 35A switch mode power supply for my amateur radio equipment. Working great for last 7 years. Recently it's now producing "swooshing" noise in my radio receiver, especially on frequencies from 1.8-10MHz. Took it apart and noticed blown tops on the 3 output filter electrolytics, so I replaced those. But that did not help.

I could replace the 2 larger input filter electrolytics but they "look" OK and I wonder if maybe I should be thinking of also replacing the switcher MOSFET - I don't know where else the noise could be coming from?

Any ideas greatly appreciated.

a) Replace all the caps. Unless you have both X-ray eyes and an ESR meter, you have no effective way of discerning whether they are good or not.
b) If it works otherwise - that is, produces the correct voltage - unlikely that the MOSFet is bad.
c) It becomes a close-run thing whether the cost/time involved in repairs exceeds the value of the device if it is more than just the caps.

Peter Wieck
Melrose Park, PA