Fehlmann Picomax 50 CNC conversion/refurb

[EddyCurrent]

Thanks for the reply. What's a "charge pump"?

if the bob does not see a continuous signal from the controlling PC it shuts down.
Also called a 'watchdog timer'

From my bob manual,

The charge pump uses the 12 kHz signal from the parallel port generated by the
CNC software to operate a logic circuit that gives an active low output. Any
piece of machinery that uses powerful motors can be dangerous if controlled
by a computer that can be in an unknown state while being powered up or in
a software crash condition. Using the charge pump circuit to disable power to
motors is a safety device in that it only operates when the software is running
correctly and under user control. The charge pump circuit is also used to
disable the output signals so even if your stepper boards do not have an
enable pin they will be disabled automatically when the charge pump signal
is not present.