This cap was removed from a 70's-80's German industrial machine:
It has no polarity markings. One terminal is common with the metal case. Is this always an indication of the (-) terminal?
The base has molded terminal locations numbered 1-4, two of which are empty:
Markings on the side are:
B41111-B7108-T 1000uF 40V- GERMANY GPF DIN 41332 06.78
I find a few references to a Siemens part that is similar:
but no datasheet can I find. Can someone more resourceful than I find one?
I cut open one of these caps. It is paper & foil (or so it seems) spiral wrap construction. Can polarity be determined by internal construction? Is the center terminal always one pole (ie, always +)?