a real challange?

[Notimetolooz]

The mark on old vintage cylindrical caps indicated the lead connected to the outer layer of the foil. It is not at positive-negative polarity. In some situations it was thought the outer foil should be connected to the side of the circuit that is more closer to the signal ground (AC wise).
I have seen someone suggest you could determine the outer foil side of new capacitors by connecting one end at a time to a scope probe and hold the sides of the cap in your fingers. (Maybe you have to connect the other cap end to the probe ground lead.) The bigger signal (noise pick up) on the scope is when that end is connected to to outer foil end. I never tried that, but I see that it could work.
I don't think I ever thought it was necessary however.

[Yamamaya42]

Originally Posted by Notimetolooz

The mark on old vintage cylindrical caps indicated the lead connected to the outer layer of the foil. It is not at positive-negative polarity. In some situations it was thought the outer foil should be connected to the side of the circuit that is more closer to the signal ground (AC wise).
I have seen someone suggest you could determine the outer foil side of new capacitors by connecting one end at a time to a scope probe and hold the sides of the cap in your fingers. (Maybe you have to connect the other cap end to the probe ground lead.) The bigger signal (noise pick up) on the scope is when that end is connected to to outer foil end. I never tried that, but I see that it could work.
I don't think I ever thought it was necessary however.

I was using the term (negative side ) in a general sense as the chassis ( or ground ) is genitive in this set.
Example
https://imgur.com/KouQqr3
C85 C84 have outer foil side to gnd
https://imgur.com/T9pHSAI

Now, depending on who is asked :/ ( ask 4 people get 4 dif views, ) it may, or may not matter which way the new style film cap is put in.
some sources say it does not matter...
this says it does, :/
https://www.youtube.com/watch?v=BnR_DLd1PDI
mentions the o-scope test.
just wondering who to believe...

[Electronic M]

Originally Posted by Yamamaya42

I was using the term (negative side ) in a general sense as the chassis ( or ground ) is genitive in this set.
Example
https://imgur.com/KouQqr3
C85 C84 have outer foil side to gnd
https://imgur.com/T9pHSAI

Now, depending on who is asked :/ ( ask 4 people get 4 dif views, ) it may, or may not matter which way the new style film cap is put in.
some sources say it does not matter...
this says it does, :/
https://www.youtube.com/watch?v=BnR_DLd1PDI
mentions the o-scope test.
just wondering who to believe...

I've ignored outside foil in 3 RCAs of that period (and basically everything I work on) and not had any issues.

The idea of connecting the outside foil to low impedance is to shield from noise. Modern film caps are much smaller and thus have less foil and lead area (smaller caps usually get wired with more direct wiring in a restoration), and are less prone to noise pick up....there might be some special cases where it makes a noticable difference, but in most cases it is more trouble than it is worth...

[Yamamaya42]

Originally Posted by Electronic M

I've ignored outside foil in 3 RCAs of that period (and basically everything I work on) and not had any issues.

The idea of connecting the outside foil to low impedance is to shield from noise. Modern film caps are much smaller and thus have less foil and lead area (smaller caps usually get wired with more direct wiring in a restoration), and are less prone to noise pick up....there might be some special cases where it makes a noticable difference, but in most cases it is more trouble than it is worth...

thanx for the info, that is what I was looking for!

the stuff came today btw!

[Electronic M]

Originally Posted by Yamamaya42

thanx for the info, that is what I was looking for!

the stuff came today btw!

Happy to help.