ThinkJet 2225B battery pack question

[hfischer]

(05-12-2020 09:27 PM)John Keith Wrote:  Looking at your diagram, does the choke consist of two separate windings on one core? If so, it is probably a common-mode choke which is used to filter out line noise.

Yes, this can be seen quite nicely on Dave's third picture: looks like about 20 windings of two adjacent wires on a small helical core. The core looks like plastic, not ferrite.