EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: InductorbackEMF on May 16, 2019, 07:25:15 pm
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So i was fixing a remote thingy, when all of a sudden i hear a small hizz then a loud hizz,i look up and see my lamp buzzing and letting the magic smoke out,i rush it out the room thinking the inductor/ (or ballast) somehow died and set light,well when i opened it guess what i found... :)
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And yes there was a bunch of cracks in the case as always.. :palm:
Alex.
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Crappy Rifa firecracker yet again.
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I have had paper capacitors from 1940 last longer than this. :-DD
Alex.
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Wow, we're averaging about one a week at the moment!
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RIFA DETECTED!!!
(https://thumbs.gfycat.com/IlliterateObeseGoldfish-size_restricted.gif)
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I still have only ever had one of these fail, and it was in a 25 year old at the time Apple IIe. Maybe they fail more often in 240V land?
While less spectacular, I've had waaay more electrolytic caps fail, even good name brands.
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I still have only ever had one of these fail, and it was in a 25 year old at the time Apple IIe. Maybe they fail more often in 240V land?
While less spectacular, I've had waaay more electrolytic caps fail, even good name brands.
They usually explode after equipment was not powered for some time. Of course they have higher chance exploding at higher voltage.
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If it's used as a snubber, rather than EMC, it will have a resistor, so will need to be replaced with one with a similar resistance, as well as capacitance or separate resistor and capacitor, wired in series.
http://www.farnell.com/datasheets/300514.pdf (http://www.farnell.com/datasheets/300514.pdf)
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i know a shop with a whole drawer of NOS rifa's full of cracks, they cant bring themselves to bin them! :-DD
i'll take a photo next time i'm there. ;)
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If they're old stock with cracks I'd obviously toss them. Likewise if I had a box full of old stock electrolytic capacitors that had high ESR or were leaking I'd toss those. I wouldn't hesitate to use a new RIFA or electrolytic capacitor in something though, it is well understood that these are consumable parts with finite lifespans.
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I may be shot down here :D
When you said a 'Lamp', you didn't explain/show if it was a 'Fluoro' ??
As such, the Capacitor would have been present for 'Power-Factor-Correction",
(due to the Ballast (Inductor) being present.)
Many times, I've just cut the Capacitor out! from Fluoro units !!
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It appears to be too small to be a power factor correction capacitor., but it's difficult to get a sense of scale from the photograph, so you could be right.
Inductive ballasts can create a burst of radio frequency interference when starting up, so a capacitor is normally needed to suppress it. The starter quite often has a supressor capacitor built-in, but it wouldn't surprise me if some fittings also have an additional one, just in case.
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It appears to be too small to be a power factor correction capacitor., but it's difficult to get a sense of scale from the photograph, so you could be right.
Inductive ballasts can create a burst of radio frequency interference when starting up, so a capacitor is normally needed to suppress it. The starter quite often has a supressor capacitor built-in, but it wouldn't surprise me if some fittings also have an additional one, just in case.
Flouros generate RF all the time. Just take an AM radio into a room with flouros on. Not sure which is worse magnetic or electronic ballast.
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It appears to be too small to be a power factor correction capacitor., but it's difficult to get a sense of scale from the photograph, so you could be right.
Inductive ballasts can create a burst of radio frequency interference when starting up, so a capacitor is normally needed to suppress it. The starter quite often has a supressor capacitor built-in, but it wouldn't surprise me if some fittings also have an additional one, just in case.
Flouros generate RF all the time. Just take an AM radio into a room with flouros on. Not sure which is worse magnetic or electronic ballast.
Electronic ballasts yes, but magnetic ballasts don't radiate much over the AM radio region, other than a short burst at turn on and off.
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Hi,it seems like the capacitor was only for EMC so no worry's i have replaced it with class x capacitor same value. (Not a rifa hehe)