VT100 PSU smelling.
tothwolf at concentric.net
Sat Jan 23 21:33:35 CST 2016
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.
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