Film Capacitor Query

[jsa_ind]

Why do Film Capacitors have a short and long leads. Do they have any significance? If so, could someone please advise?

Also can someone assist in mentioning the simplest way to determine the a film capacitor's outer foil ?

Thanks

 

[mjf]

........the shorter lead should be the outer foil - see mundorf site

https://www.mundorf.com/audio/en/shop/Capacitors/Audio_Caps_EVO/MCap_Supreme_Evo_SGO/

 

[WntrMute2]

I posted THIS a while back. Might be worth a try.

 

[diepiolet]

I use a DMM and check the resistance from touching the outer portion of the barrel and either lead.
One lead will have a lower reading, that is the outside of the wrap. It should be AWAY from the positive or toward the negative for a noise rejection install. The few that might be difficult to differentiate are usually very small in diameter.
Big caps are pretty easy. Change the battery in the DMM, ay. 🙂 It's kind of the SOP for me any more if it's been a while.

It's not the perfect way, but it works. I clean the leads and plugs too. It takes 5 seconds to be consistent to a point. Clamp the lead and use a probe for the barrel. Don't use your fingers as clamps.

I just went through a pile myself for a/my Cary SLP-05 and a second V12r I added to the mix.

Have fun.

 

[WntrMute2]

I use a DMM and check the resistance from touching the outer portion of the barrel and either lead.
One lead will have a lower reading, that is the outside of the wrap. It should be AWAY from the positive or toward the negative for a noise rejection install. The few that might be difficult to differentiate are usually very small in diameter.
Big caps are pretty easy. Change the battery in the DMM, ay. 🙂 It's kind of the SOP for me any more if it's been a while.

It's not the perfect way, but it works. I clean the leads and plugs too. It takes 5 seconds to be consistent to a point. Clamp the lead and use a probe for the barrel. Don't use your fingers as clamps.

I just went through a pile myself for a/my Cary SLP-05 and a second V12r I added to the mix.

Have fun.

Does this work if the capacitor case is non-conductive? Seems it wouldn't.

 

[Rod Coleman]

Does this work if the capacitor case is non-conductive? Seems it wouldn't.

No - but it's still usually possible to tell. DMMs with capacitance reading are fairly low cost now. Connect one test-lead to a cap-lead. attach the other lead to a «search plate» - a piece of copper foil or some otherpiece of metal. The outer side will naturally give more capacitance when the search-plate is held near the cap's body.

Many rectangular caps don't have an inner/outer format. These caps are symmetrical, because they are of stacked-construction: the plates are stacked alternately (interdigitation).
for power supply caps, the Stacked construction MKP caps are usually to be preferred - exampl: DC-Link types.
These have very low ESR and ESL.