Need Help with Metal Film Capacitor

Thread Starter

electronewb

Joined Apr 24, 2012
260
I'm trying to get this right.

I assume it's 400V? Does the dot below 400 mean anything? What's the FI stands for? And where is the capacitance value?

And finally would those be the exact same thing as the one I have?
 

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crutschow

Joined Mar 14, 2008
34,680
The 400 likely is the voltage rating.
The capacitance is 10,000pF or 10nF or 0.01μF.
The K likely means 10% tolerance on the capacitance value.
The other characters may be just manufacturer's markings.
That ebay cap looks sufficiently similar to the one you show to be a replacement.
 

Thread Starter

electronewb

Joined Apr 24, 2012
260
Yep it's used with 90VAC. Now what would be the reason why they don't make contact anymore? But soon as I apply heat like when I unsolder the switch and the cap the microswitch comes back to life?
 

ian field

Joined Oct 27, 2012
6,536
Could be oxidation on the contacts.
When you put a capacitor across a switch that handles AC, every so often the switch closes at the voltage crest (maximum charge on the cap) - little by little this sputters the contact surfaces away.

Generally best to put at least some resistance in series with the cap so it doesn't play spot-welder with the switch contacts.
 

GopherT

Joined Nov 23, 2012
8,009
Copper can be cleaned using thermal shock. It is possible that very smooth surfaces will come clean with rapid heating.
 

Thread Starter

electronewb

Joined Apr 24, 2012
260
OK so I went to an electronic store they have lots of parts there and I couldn't find a 0.01uF at 400V not of that size anyways. I found a 100V that's just a bit bigger and a 600V that's almost twice the size. Even the sales guy was surprised to see that little cap to be rated for 400V. Can i use different types of caps for that applications?
 

R!f@@

Joined Apr 2, 2009
9,918
Those are the types mainly used for. If you are sure it is switching 90VAC, you can suffice with 275VAC ones as they are available.

Another type suitable is MKT box capacitors
 

Thread Starter

electronewb

Joined Apr 24, 2012
260
Could I replace those flimsy microswitches with a solid ON OFF ON momentary toggle switch? It's for a pan & tilt controller that moves a security type camera. Right now I have a joystick ( http://www.directindustry.com/prod/apem/micro-switch-joysticks-7593-520272.html) pan left and right and tilt up and down. I think it would be more reliable to have toggle switches instead one toggle switch for the pan L & R and another toggle switch for the tilt UP & DOWN would there be an issue with the controller?
 

Thread Starter

electronewb

Joined Apr 24, 2012
260

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