Help with film capacitor identification

Hi Everyone,

I was wondering if someone here might be able to assist with identifying the make and series (or type) of film capacitor that is used in the attached photo. The manufacturer of this device offers an upgrade to Evox capacitors but doesn't specify the series or type. I'm hoping that if I can establish more about the stock caps it will help me narrow down which Evox caps they use in the upgrade. So far I have not been able to get any internal pix of a unit with the "Evox upgrade", however at least one of their other products uses blue film caps that I suspect are Evox PFR. I can't justify paying for the cost of the upgrade when I know it's only a few $ of caps I can swap out myself.

Thanks in advance
 

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johnego

Member
2017-12-17 3:13 am
The orange capacitors are Philips (MKT) or its copy. Evox Rifa (now bought by Kemet) has the blue Evox PFR, which is very very good but the size is around pF. The Evox CMK is I think polycarbonat, which is good enough and very slightly worse than WIMA. MMK (this is white, smaller than Philips) I think is from Evox too, I think is a ceramic, not really much better than Philips MKT.


My prediction is that they upgrade the 100n Philips MKT with 22nF Evox PFR. If this capacitor is only to bypass the electrolytic (canned) capacitor then the value doesn't have to be 100n, especially when the quality is as good as the PFR. It's not easy tho to find big value PFR.


BTW, many fake Evox these days.
 
If the capacitor is simply being used to bypass an electrolytic, and assuming that the electrolytic actually needs to be bypassed (which most do not), then almost any ordinary commercial quality film capacitor will do the job. There may be a slight preference for caps which are physically small and hence have low inductance. An ordinary polyester cap will be fine. You might even get away with a ceramic. If the electrolytic does not need to be byassed then you might get slightly better performance by removing the film cap.
 
I appreciate the comments and insight everyone.

I did some research and discovered Evox PRF caps aren't available in 0.1uf, so if the original values are preserved with the upgrade, I can eliminate them.

johnego makes a very good point however, as there are four locations on the board where the film caps are being used as bypass caps on electrolytics. Perhaps the $100 USD factory upgrade merely addresses the four bypass caps, in which case 22nf PRF caps are still an option.

Another Evox branded blue capacitor is the PHE426 series, which does come in 0.1uf 63v from Digikey and Mouser.

I'm attaching a full picture of the original board.

JMFahey, to answer your question about what we are trying to solve here: I'm hoping to secure the bragging rights that come with a Evox upgraded device while only spending a few $. I certainly respect how some might doubt the benifits of a small cap change, but I do trust that the manufacturer has some reason to offer such an option.
 

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analog_sa

Member
Paid Member
2002-08-14 1:47 pm
Cascais
What a fascinating thread.

I was thinking that in a purely digital environment none of these mylar caps will do much useful bypassing. Rather use Panasonic ECPU smd although those are notoriously sensitive to soldering.

Then again, is this really a digital board? Its application may be digital, but it outputs a sine wave. Which doesn't make the mylars any less baffling.

If this was mine i would use the Panasonics and would definitely replace all the tantalums with organic polymers.

Something else that baffles me is the absence of a decent regulator next to the actual oscillator circuit which looks like a discrete Colpitts.

Very weird and many thanks for the pic.
 
I did some further research today, and I think Evox cap upgrade is something entirely different than what I was asking about here. Instead of film caps on the clock board, I now see some units have a Evox / Riva PEG226 series electrolytic on the power supply input board, presumably as a filter. The non-upgrade units have a cheap Samyoung cap in the same location.

Thanks to all who contributed their expertise.