HP6622A Power Filter Exploded

[Cyberdragon]

I left my HP6622A plugged in and the power filter exploded. I threw it outside 'cause it was on fire. BUT REALLY?! Isn't that what fuses are for! This thing has a UL rating, it shouldn't explode if a component fails!

Did this thing seriously have the filter before the fuses?! Or did some jerk before me put higher rated fuses in it?! (if the filter caps were leaky it could have kept blowing smaller fuses)

Now I need to clean up the fire damage and get a new filter that will not explode. Is it worth trying to fix the burnt one or can I get a new one that will fit this unit?

Once it stops smoldering I'll see if I can get some photos of the damage. IDK what else blew up in it, but the filter was where is was smoking the worst.

[c4757p]

Filter before fuses is common. Fucking bloody stupid, but common.

Does the filter say "Schaffner" on it? Usually the ones that almost cause a house fire do.

[Cyberdragon]

IDK What brand it is (was). That piece is missing.

Money shot!

KAAABLAAAMO!

(The insert image is being stupid, and so is attachments)

EDIT: EEEWW! That little devil! Now it's gonna stink in here for a week!

[free_electron]

Oh yes, those capacitors are notorieous for going kaboom. Same type used in those 'paffner' (schaffner) filters.

[Cyberdragon]

How did this thing ever pass a UL rating with that garbage in it? Now I'm going to have to rewire the whole nonsense to make it safer, and clean up the fire damage!

Should I bodge a fuse in line with the new cap or replace the whole filter and plug box? (the rest of the damage still needs to be assessed though)

Also, given that I don't think I have any non-pcb power caps, would a motor start capacitor work? (it would have to be a really small one at max 1uF, I assume these have safety ratings, unlike that one)

[amyk]

How old is it? UL now is not UL then...

I can see the brand in the top part, it's a RIFA polystyrene.

If it is the one across, the mains, it is C0 in the schematic and it is 250V, 0.22uF.

[Cyberdragon]

Yep, that one. I think its from the late 80s by the dates on the chips, maybe early 90s.

[edpalmer42]

Don't worry about the fuse!  If you look at the schematic, the fuse is exactly where it's supposed to be.  Don't forget that it's an 8 amp fuse.  It's quite possible that the current didn't reach that point or didn't stay there long enough, for the fuse to blow.  I have the same power supply.  It's equipped with an SOC CES4 fuse rated at 8 amps.  I can't find the spec for that fuse, but it appears to be rated for high inrush currents.  If that's correct, it's rated to take 20 amps for 1 sec.  If someone put a slo-blow fuse in, it will take even longer to blow.  Check your fuse to see what's there.

Finish the cleanup and see what you've got.  I wouldn't be surprised to find out that nothing else has been damaged, although it probably looks like a disaster in there.

The only thing that does surprise me is that the capacitor blew in the first place.  I've read the messages about Schaffner filters blowing, but typically those reports involved capacitors that had spent their lives with 220V - 240V across them.  I'm surprised that a 250V capacitor would have trouble with 110V.

Ed

[KJDS]

I've had a few go about 20 minutes after being powered up for the first time in a few years.

[johnh]

Had similar capacitor blow up in Tek 2430A

https://www.eevblog.com/forum/testgear/tek-2430a-magic-smoke-from-low-voltage-power-supply/msg376187/#msg376187

[T3sl4co1l]

Yes and yes; clearly, these old (crazed and cracking) Rifas aren't doing quite as well as they were intended to.

I don't think I have any salvaged Rifa that aren't crazed.  Needless to say, I won't be putting them in any line filtering applications.

Tim

[han]

i experience twice,
both filter exploded from two Old HP SDH BER tester.
Its explode after store for prolonged time in humid, so the capacitor absorb some moisture.
I hear boiling sound before it's explode in very smoky explosion.

[tautech]

i experience twice,
both filter exploded from two Old HP SDH BER tester.
Its explode after store for prolonged time in humid, so the capacitor absorb some moisture.
I hear boiling sound before it's explode in very smoky explosion.

I've caught a couple before the BOOM by just doing a blow out or cracked cord repair.
They often have cracked outer cases, allowing humidity to invade, then BOOM.

Quite common in all sorts of equipment and appliances.
There are many threads on this matter.

[Smith]

Same RIFA's as a lot (most or all) Philips PMxxxx scopes. Replaced mine as it was already cracked and discolored, most of them eventually explode as yours did. The Schaffners mains IEC inlet filters in older HP scopes had the same issues, some of them exploded.

[SoundTech-LG]

Notorius...   Philips PM3263 smoked my kitchen. RIFA bomb.

[marinedalek]

Ah yes, had a similar thing happen to a ~1980 vintage Yamaha organ. Around 20 minutes after being switched on (after several years' languishing in a cupboard), poof goes the cap.



 Subsequently bought another organ for parts and the cap was already blown on that one... these things do not age gracefully!