On Sun, 20 Nov 2016 11:49:38 -0800 (PST), 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.

I can't tell from here where the noise is coming from. Usually, I put
a small loop antenna on my spectrum analyzer and save it around the
power supply while under load. That usually locates the general area.

Much more interesting is why three capacitors would decide to bulge.
Bulging is usually caused by excessive ripple current through the
filter capacitors. High ripple could be coming from the diodes, or
simply from undersized capacitors that can't hold a charge between
switching cycles and therefore draw more current than normal.

I suggest you put a scope on the output while under load and see if
there's any ripple present. Compare the value with the manufactures
specs. Also, use an IR thermometer to measure the case temperature of
the capacitors. If they are getting warm, then there's ripple current
going through them.

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