About Zenit AM
As I had to disassemble the Zenit AM No. 93000001 for cleaning, I took the opportunity to study it:
The main electronic board is at the right of the mirror block.
The shutter releasing of the AMs is mechanical (which explains that the socket for electrical trigger of the Automat was replaced on the AM series by a socket for external power).Therefore, when you press the selftimer button of the AM, you mechanically release the shutter, and an electromagnet holds the mechanism about ten seconds. This must lead to overconsumption of batteries, and perhaps problems of life of the electromagnet.I show this electromagnet with an arrow on the photo. It and the little board in front do not exist on the AM2.
The Shutter:
It's name is FZL-84 and I find it splendid.
Lens side, idle (left) and cocked (right).
Film side, idle (left) and cocked (right).