"DaveC" skrev i meddelelsen
obal.net...

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.

Hmm. The box-with-a-triangle symbol looks like a logic gate to me.


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.

Probably some safety loop required/mandatory wherever the machine was first
sold; the cutter will not operate when certain hatches wired with door
swithces are open e.t.c. Machines are often customised - even the same
machine from the same manufacturer can be somewhat different. If they are
picked up used or at bancrupcy auctions - as I like to do - it will show.


Is the triangle within a square symbol some sort of odd representation of
a
transistor? And the "arrow thing" that feeds them? Ideas?

I really think they are logic gates, it looks a bit like the way Siemens
would draw them. The box-with-triangle-at-top looks like some kind of limit
switch, probably pneumatic.

The individual gates may well be implemented with a bunch of discrete
components, including transistors!

Guess you have to dig out the ole meter and walk the wiring in the terminal
blocks* - ohh those were the times ;-)



*Often the wiring is wrong too - yet the unit still worked thousands of
hours with the fault. This should not worry you unduly. Muahahahaha ;-)


Help!

Thanks,
--
DaveC

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