Help identifying a blue ceramic capacitor

[Spork Schivago]

Hello everyone.

It's me again. I got another question. I'm working on a stereo amplifier / receiver. The switch was bad and attached to the switch was what I'd call a blue ceramic capacitor. I believe these are high voltage capacitors. I've seen them before.

On this one, there are some markings. Besides the logo's and stuff, there are the letters MY, on the next line 472P, on the last line it says 8 46. The 8 might be part of a logo though. I can upload a picture if someone wants.

I believe the 472p means it's a 4700 picofarad capacitor. I am uncertain of the voltage though. It is attached to the two prong switch. Can I just use a normal ceramic capacitor that is 4700 picofarads that has a voltage rating of around 250v?

I tried testing it with my Atlas ESR 70+ meter and it didn't even register. I also tried testing it with my Atlas DCA meter and it wouldn't register on that either.

Thanks.

[budm]

Re: Help identifying a blue ceramic capacitor

That is the snubber cap, 0.0047uF, to take care of the arcing when the switch is open, 250VAC or Higher. If you look at the cap and see the voltage rating printing on it, most of the time that is DC rating not AC. For example 0.1uF 250V, it means that you can apply 176.75VAC RMS or 250VDC on it without the cap breaking down.
The safety cap X/Y type you will see 250V~ on it = 250VAC.

[Spork Schivago]

Re: Help identifying a blue ceramic capacitor

That is the snubber cap, 0.0047uF, to take care of the arcing when the switch is open, 250VAC or Higher. If you look at the cap and see the voltage rating printing on it, most of the time that is DC rating not AC. For example 0.1uF 250V, it means that you can apply 176.75VAC RMS or 250VDC on it without the cap breaking down.
The safety cap X/Y type you will see 250V~ on it = 250VAC.

Okay, thank you. Does this snubber cap need to be a blue one? Or can I use one of those tanish coloured ceramic capacitors with the correct voltage ratings? Perhaps the tanish ones aren't for AC voltages? Just a thought.

Also, what do you mean by the X/Y type? X = farads, Y = voltage?

[budm]

Re: Help identifying a blue ceramic capacitor

X/Y cap is the term used when we talk about safety cap that is connected across the Line and Neutral (X) of the AC Primary circuit, or when it is connected between Line and Safety Ground (Y), or Neutral and Safety Ground (Y).
Color just what the manufacturer pick. I would suggest you to use X/Y type cap because when they fail, they fail open circuit, Ceramic cap when it fails, it fails short circuit (it short itself out).
I recommend PANASONIC ECQUL series from DIGIKEY.

[Spork Schivago]

Re: Help identifying a blue ceramic capacitor

Budm, I cannot find the ECQUL series on DIGIKEY. They have the following series: ECC, ECD, ECJ, ECK, ECU-S, ECY, GL, HD, KBP, KGE, MEH, NS-A, TS and VS.

I'm under the ceramic capacitor category. The other categories are Aluminum, Arrays, Electric Double Layer Supercaps, Film and Tantalum. Am I under the wrong category or do they truly not have the Panasonic ECQUL series capacitors? If they don't have them, can you suggest another series perhaps?

Would something like this work? http://www.digikey.com/product-detai...0468-ND/268440
It's from the TS series. For the ratings, it says it's an X1/Y2. Also, on the search page, it says quantity available 1-immediate, with a minimum quantity of 5 then it says non-stock. That means they can still get it for me, right?

Thanks.

[budm]

Re: Help identifying a blue ceramic capacitor

http://www.digikey.com/product-detai...0996-ND/295842

http://industrial.panasonic.com/www-...QU2A472ML+7+WW

[Spork Schivago]

Re: Help identifying a blue ceramic capacitor

Thank you. I ordered 5 of them just in case I need them again in the future.

[Spork Schivago]

Re: Help identifying a blue ceramic capacitor

Hey, how do I test these film capacitors? I'm wondering if the original capacitor might still be good. I hooked both up to my capacitor meter and got no reading. I thought because of the low farads, maybe my DMM in capacitor mode would work. Didn't get a reading any where close to what it should be. My capacitor meter is an Atlas Peak ESR 70+ meter. I also tried my DCA55 meter and got nothing. I wasn't really expecting anything from the DCA meter though. I made sure the capacitor was discharged before hooking it to the DCA meter. Any thoughts? Thanks.

[budm]

Re: Help identifying a blue ceramic capacitor

Should read .0047uF. What is the lowest capacitance can your meter read? Do you have any other cap in stock with about the same capacitance for testing?
According to Amazon, it is from 1uF~22,000uF
http://www.amazon.com/Peak-Electroni.../dp/B005NIBEYU

[Spork Schivago]

Re: Help identifying a blue ceramic capacitor

I was thinking about the ESR meter and remembered that it couldn't read such a small capacitance. However, I believe my DMM can. It's a Craftsman 82357 DMM. I cannot find the manual for it, but when I put it on capacitance with nothing hooked up to it, it shows 00.05nF's. This capacitor should be reading 4.7nF's, right?

I do have a 4.7nF ceramic capacitor that reads 4.66nF's on my DMM. Would the reason my DMM cannot read the film capacitors I ordered be because of the higher voltage that they're rated for and because they're rated for AC, not DC?

[Spork Schivago]

Re: Help identifying a blue ceramic capacitor

Hey, after I tested the ceramic capacitor, now the DMM is reading the film capacitors. Also, the old snubber cap that was on there is testing. Not very good though, it goes up to around 3.53nF's and then jumps back down and starts charging again. So I'm still going to replace it. I think I'm good now though. Thanks.