On Mon, 8 Dec 2008 23:22:17 -0800, DaveC wrote:

:This is a partial wiring diagram for an early 80's (West) German guillotine
aper cutter:
:
:http://freefilehosting.net/show/42l0i
:
:The goal of this circuit is to energize an electromagnetic clutch coil (m27)
:that takes rotational energy from a flywheel to do a task (bring down the
:knife blade). This circuit is currently not working.
:
:This machine has no ICs. There are some monolithic rectifier bridges and
:discrete transistors (the common symbol for which I cannot find *one* in the
:diagram), and plenty of passives.
:
:The transformer (m) primary center tap is connected to 24vdc. Do I interpret
:this correctly that the primary is run by a switched dc voltage? (This on a
:machine that runs on 3-phase 245vac.) Why?
:
:I can say from experience that other machines of this same manufacturer use a
:voltage derived directly from the 3-phase input to drive the electromagnetic
:clutch. Why use a switched voltage, I cannot understand.
:
:Is the triangle within a square symbol some sort of odd representation of a
:transistor? And the "arrow thing" that feeds them? Ideas?
:
:Help!
:
:Thanks,

Not even LM Ericsson x-bar schematics use such nondescript symbols, and their
symbols took some getting used to back in the 60's.

I'm afraid you are going to have to trace out the wiring while comparing it with
the schematic and that way you should be able to work out what each of the
nondescript items with the triangle symbols are. My guess is that they indicate
some sort of active semiconductor function block. There may be additional
schematics detailing what is in each block but if that were so then one would
expect to see some identifier number written inside each block but I don't see
this information either.

Good luck!