[GreenKeys] why does my ksr28 elsu look so sparse!?

[Jim Haynes]

Because it doesn't take much of a LESU for a basic printer set.

One function is fusing and turning the power off and on.  That occupies
one end.  Then there are the selector magnets and keyboard contacts, and
the selector magnets go to a plate on the other end.  Often there is
a line shunt relay, arranged to short the line if the keyboard or typing
unit is unplugged.  This is for cases of machines actually run on a
series circuit, where opening the loop kills it for all the machines.
So it is necessary to shunt the line to keep it working when the set
is taken apart for maintenance.

Options include a line relay, and the line relay requires a power supply.
Then some machines have a motor control latching relay, such that
FIGS-BLANK-H turns off the motor and a break in the line turns it
back on.  Some machines have a LINE-TEST key on the LESU, which also
requires a power supply, though it can use the one provided for the
line relay.  There are a couple of other motor control relay options.
There is an electronic selector magnet driver, but if you have that
you don't need the line relay and its power supply.

jhhaynes at earthlink dot net