Capacitors - How to install?

[norman]

I just received my replacement caps in the mail. They are IC metallized polypropylene wrapped axial lead type (MPW). My question is the ones I am replacing have a line around one end and these have no markings. Does it make a difference which way I put them in?
Thanks, Norman

 

[Thatch_Ear]

Nope. These high voltage coupling caps? If so bring it up on a variac so you don't ruin them.

 

[norman]

Yes 400 volt on the old ones. the new ones are 630, which I imagine should be better. The only other question(maybe not only) is how slow is "slowly" on the variac??
Thanks again for info.

 

[GRollins]

On older caps, the lead attached to the outside foil was considered to be the negative because it shielded the inner foil, thus being somewhat quieter. Some of the boutique caps used to (may still for all I know, but I haven't seen it in a while) mark their outside foil for the same reason. I think Percy marks his film caps with a marker to show the negative lead. How he tests them, I do not know.
Note that a film cap will function safely either way; it was just for that Nth degree of performance.
I'm not sure I follow the reasoning on bringing a film cap up on a variac. If you're confident that you've got the right cap in the right place and that the solder joints are good...turn it on.

Grey

 

[AudioFreak]

Yeah you should just be able to turn the thing on with the new caps in and be done with it.... it's only high voltage electrolytic caps that need special treatment.