DaveC wrote in message
obal.net...
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,
--
DaveC

This is an invalid return address
Please reply in the news group



repost to
de.sci.electronics
perhaps


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/