Neotec NT-2701 Capacitor

EagleTG

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I need to replace C423 on this monitor. Bob Roberts doesn't carry this cap, so I placed an order with Digikey. The one I got from them is far smaller than the factory cap. I've apparently made a mistake in my order. I know some newer caps are smaller than old ones, but this seems too much-so.

Here's the cap I got. It looks like my mistake was that it is Polyester, not Polypropylene.
http://search.digikey.com/scripts/DkSearch/dksus.dll?KeyWords=E4563-ND

The original capacitor was labeled ME 604J-400 (was replaced once before, I think this is a 400v capacitor while the original is 250v from what I can find online), naturally the larger replacement is OK and probably preferred in this application.

I'm assuming I need a Polypropylene to make this work. Can someone confirm that the following cap is correct for this application (or that the one I already have will work)?
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P12080-ND

My concern is that the size of the polypropylene doesn't seem much different than the polyester according to DigiKey's site.

Thanks!
 
Depending on the circuit, the polyester (might) work fine.....but if the original was polypropylene, I'd stick with polypropylene. Polypropylene caps are generally more expensive than polyester......and there's a reasonn why the designer used it. I wouldn't worry too much about the physical size....just make sure the voltage is in spec (or higher).

One thing I did notice.....you're ordering a .056µf caps.....the original cap number you posted (604j) is a .600µf cap. That's a pretty big difference.

Edward
 
Depending on the circuit, the polyester (might) work fine.....but if the original was polypropylene, I'd stick with polypropylene. Polypropylene caps are generally more expensive than polyester......and there's a reasonn why the designer used it. I wouldn't worry too much about the physical size....just make sure the voltage is in spec (or higher).

Ok, thanks.

One thing I did notice.....you're ordering a .056µf caps.....the original cap number you posted (604j) is a .600µf cap. That's a pretty big difference.

Edward

Ahh... That might explain it. I had very little luck finding info on the 604J part number, and am more familiar with markings on electrolytics (don't get too much experience with Mylars/Polys). I was actually going off of information garnered from the schematics. I did notice that there are apparently a bunch of different sub-versions of this monitor, it seems that the schematics aren't necessarily guaranteed to be correct from what I read on this one.

I have looked briefly, but is there a tutorial or explanation on cap markings of this type? I think I understand that the number is generally the 3 digit number multiplied by 0.001 and that the letter represents tolerance. Is there a secret decoder ring for these that you know of?

Thanks for the assist. I will try ordering a 600pF (.6uF) cap in Polypropylene and see if that changes things.
 
Yeah, .6uf is an odd size.... .62uf MIGHT work. Once again, it dependson the circuit. I've been running into the same problem lately....not being able to find the right size of polypropylene I need. I've been tying two together to create the value I need. Does Digi-Key have two .300uf in stock?

Edward
 
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