Mains Line Filter Cap Failures on PSU Test Equipment

[BradC]

Having you considered trading the wife in for a new scope

Hell no. It took me 20 years to find one that entertains my thing for tools. If I can justify it, I'm allowed to buy it. She even comes along shopping some times to look at all the shiny things.
The only behaviour I've had to "adjust" is the "it's broken, let's buy a new one". I much prefer, "it's broken, let me spend 12 months planning out how I might fix it and save yet another item from landfill". That usually winds up with the compromise that I'll fix it now, but I need this new tool to do it Everyone wins.

[wagon]

I've replaced those caps in all manner of stuff.  Not a complete list, but here goes.
Kawai organs
Yamaha organs
(with the organs the customer will report a 'bang'and sometimes a stink.  They are used to supress 'pops' on power up or off.  The instrument works OK without them, but I change them anyway)
Clipsal 'C-Bus' lighting controllers
Daken M70&M100 electric fence energisers
Various sewing machine pedals

Whatever that crap is that comes out of them, it's very hard to clean up.  Acetone, carby cleaner, thinners, isopropanol, etc. all move some of it, but not all.

[wagon]

You could say the problem is 'Rifa' with these capacitors.
 

[nfmax]

My score of failures of these capacitors:

• A 1980's vintage ASTEC SMPSU in a computer I built back in the day
• A Wyse WY-30 terminal for the above
• An HP 3312A function generator (much cracking & popping, but it kept on working all the while)
• A Neff dishwasher (this one, on the other hand, apparently took out the circuit RCD and killed a PIR light controller, though it may have been a mains transient that did for both)

The capacitor design is supposed to be fail safe, i.e. it does not fail short-circuit. To be fair, none of my adventures ended that way

[Kleinstein]

Not failing by short circuit did not allways work. I had a Makita drill with the cap blowing - not just the cap, but also tripping a 16 A fuse and blow the next larger 35 A one. To be fair I pluged in the machine a second time after it hat tripped the 16 A braker before.

In this case likely to many sparks from a broken motor braught the cap down.

[Smith]

I had the same experience with an almost brandnew and expensive Bosch drill. The cap was shorted, and blew the 16A fuse of our house. There wasn't much to see about the cap itself. Replaced it, and I had a free drill.

Philips equipment PMxxxx scopes and some HP 54xxx scopes where known for failing and exploding mains caps.