Capacitor Value

[Cadishead]

Hi All,

I need to identify the value of a capacitor. It has 4.7K400 then I think it's "I" but I cannot really read the last letter. I have attached a photo so that you can have a look.

I would be grateful if somebody could tell me what the value of it should be.

Cheers,
Andy

 

[KrisBlueNZ]

Hi Andy and welcome to Electronics Point

4.7 μF, 400V, ±10% (the 'K' means 10%).

http://www.digikey.com/product-detail/en/ECW-FD2W475J/P16728-ND/4271850

Edit: The ones you have there look like "MKT" types made by Philips (now BC Components, part of Vishay). The data sheet for the same or similar parts is at http://www.vishay.com/docs/28132/mkt368.pdf but that value/voltage combination is not listed on that data sheet. The Panasonic one linked above would be a suitable replacement, if that's what you're looking for.

 

[Cadishead]

Thank you very much for the response, that was very helpful. I have bought some of your suggested Panasonic caps. I have also bought some 4.7uF 400V electrolytic caps. What is the main difference in functionality between electrolytic caps and the polyethelene caps which I currently have?

Regards,
Andy

 

[KrisBlueNZ]

Electrolytic capacitors are polarised! The originals are non-polarised, and for a reason. Don't use electrolytics in that part of the circuit!

Are these capacitors are in some AC mains input circuitry?

 

[Cadishead]

No, they're used in a DC circuit on the back of a detector. They are part of a high pass filter. So they're in a voltage divider circuit but now and again the odd pulse is collected by some anodes which these caps are supposed to allow to pass. I think you are right with respect to the polarisation issue because I will have negative pulse passing in the opposite direction to that of the D.C. potential gradient.