On Sat, 23 Jan 2016, Jules Richardson wrote:
On 01/22/2016 06:26 PM, Tothwolf wrote:
The translucent yellow Rifa (now owned by Kemet) class X/Y safety
capacitors in particular have a 100% failure rate and are on my
replace-on-sight list. They usually begin to show visible signs of
cracking in their outer casing before they finally go out with a bang.
It's a well-known fault, but has anyone ever known one fail and actually
cause any damage (other than to itself)? AIUI, they're there to reduce
noise from the device leaking back out onto the AC supply - a system
should run quite happily without them.
I've had maybe four or five fail on me over the years, out of several
hundred systems. They're a definite weak spot, but given that I've never
heard of one damaging anything it's the sort of thing I'd consider doing
only if I was carrying out some other repair work on the PSU.
I've seen blown/cooked series resistors (which I replace with metal oxide
resistors) and sometimes a blown fuse.
I always replace them whey I'm doing other work on a psu, however I'm not
sure I'd knowingly leave one in place since they let out a lot of smoke
when they go.
I usually replace them with a film capacitor from Epcos of the same
value and safety class.
Is the voltage rating on the US ones different (new vs. old)? I can't
remember now. I know all the old UK ones seemed to be 250V, while modern
parts were rated at 275V.
Higher voltage parts are available but they are more expensive. I've seen
300V, 350V, 375V and even 400V safety rated parts.
