Replacing “snubber” on power switch.

[saabracer23]

I’m rebuilding a power switch on an SX-750 and wanted to replace the cap labeled 103Z ac250v. That tells me it’s a .01uf caps rated at 250v ac.



Would I be able to throw one of these film caps in without issue or should it be ceramic disc type? Would one be preferred over the others? All are .01uf, first pictured being 400v rated, the other two are 600v and 630v rated.






Thanks,
Dan

 

[avionic]

https://www.mouser.com/datasheet/2/315/ABD0000C258-1222124.pdf

 

[avionic]

https://www.mouser.com/ProductDetai...GAEpiMZZMv1cc3ydrPrF0%2bjlB8SXIRu5uWCE7JvQVk=

 

[avionic]

IMO it should be a safety rated cap . 103Z is .01µf -20 /+80 % tolerance

https://www.electronics2000.co.uk/calc/capacitor-code-calculator.php

 

[saabracer23]

IMO it should be a safety rated cap . 103Z is .01µf -20 /+80 % tolerance

https://www.electronics2000.co.uk/calc/capacitor-code-calculator.php

Thanks Avionic, so like one of the two you linked to would suffice? I figured out it’s value with the tolerance and that’s why i thought one of the ones I linked to would work. Out of curiosity, what makes a capacitor “safety rated”? What could happen if I used say the wondercap rated at 630v?

Dan

 

[Watthour]

It really should be a Class Y capacitor for safety. Whatever you get that meets that criteria should be relatively safe.

 

[elnaldo]

I agree, a safety cap is what you should use in XXI century. (X2/Y2 is enough, perhaps X3/Y3 too)

X/Y Caps are tested to handle large spikes and peaks of thousand of volts.
Y caps are made to never fail shorted. X caps are made to never start a fire. Most safety caps meet both standard.

I'd leave the original in, BTW.

 

[gslikker]

I wonder, the wonder cap is dated 1975......not exactly a renewal...apart from the rating

 

[tarior]

Actually, this is the correct cap to prolong the life of your switch contacts. It goes across the switch, not from line to chassis or across the line.

https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/104M06QC100?qs=sGAEpiMZZMv1cc3ydrPrF9O2k7r3G2yZ2k0QKn5XxRg=

 

[saabracer23]

I agree, a safety cap is what you should use in XXI century. (X2/Y2 is enough, perhaps X3/Y3 too)

X/Y Caps are tested to handle large spikes and peaks of thousand of volts.
Y caps are made to never fail shorted. X caps are made to never start a fire. Most safety caps meet both standard.

I'd leave the original in, BTW.

I think I’ll throw a couple of y rated caps in my Mouser basket for future use, but I may just put the original back in since I don’t have a replacement on hand.

I wonder, the wonder cap is dated 1975......not exactly a renewal...apart from the rating

Yes, the wonder cap is a little older, but being film and spending about a year in a light duty passive pre I figured it would be better than the one that has had years of ac going to it.

Dan

 

[tarior]

X and Y caps are for line filtering, not arc suppression.

 

[elnaldo]

Actually, this is the correct cap to prolong the life of your switch contacts. It goes across the switch, not from line to chassis or across the line.

https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/104M06QC100?qs=sGAEpiMZZMv1cc3ydrPrF9O2k7r3G2yZ2k0QKn5XxRg=

You are right, those are modern "RC" snubber capacitors. I'm sure they meet the safety standards needed for this app.

Even if no human life seems in risk in this application (a short in the capacitor will just turn ON the unit), I usually use safety caps just for reliability, thinking they are connected to the main voltage for very long times, and they are rated for AC.

 

[tarior]

A couple of very short papers on the subject of arc suppression.
https://www.illinoiscapacitor.com/pdf/Papers/spark_suppression.pdf
http://www.littelfuse.com/~/media/e...load_arc_suppression_application_note.pdf.pdf

 

[perryinva]

I assume you can add that suppression cap to any AC switch, whether it had one originally or not. A lot of older gear, like the MAC1900 and MC2100/5 switches do not have one and they are known for switch problems. I was going to add one just for that.

 

[50 Green]

Snubbers are often a resistor / capacitor combination, rather than just a cap.

For another idea on saving your switch, take a look at this thread.

 

[sssboa]

In Europe we have Roxburgh 120R 0.1uf or 0.033uf RC Network caps. I install them on all power switches without protection. Also bought Kemet 400VAC safety caps, more reliable than the classic Riva caps, but should be combined with a resistor.

 

[perryinva]

The CD one listed is combo safety snubber cap with built in resistor. That is what I will add. I'm surprised it took me so long to find this information.

 

[perryinva]

While mechanically directly across the switch is best, as long as it is electrically equivalent, the majority of the benefit exists. On these two pieces of gear, directly across the switch is more of a challenge than the other end of the extension wires that go to the switch.