DaveC wrote:
This is a partial wiring diagram for an early 80's (West) German
guillotine paper 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,

Try de.sci.ing.elektrotechnik perhaps

--
Jeff