System Overview
2-57
When filament focus switches, PWM pulses will shut down for a while delay of 56mS, because operate time
of relay is about 7mS and RC circuit of coil of relay costs about 6mS. The delay time should be more than
13mS. The delay signal is produced by CD4538 and logic gates. The delay time is determined by R42, C29
and R41, C28.
10V reference
The U7 REF102 chip provides standard +10V for regulating circuit.
Interlock
The J1A-13 and J1C-13 pin of connector are connected as interlock. The interlock goes through the FDB to
verify that the FDB is in place.
Interface
J1A-12, J1A-32, J1B-12, J1C-12,
Large or small
filament switch
Over current alarm
signal output
Test point