The over voltage protection user preset potentiometer VR3 is fed from the same +2.45V
reference voltage as the other controls but connected from the main PCB via PJ1-15 as
. The OVP set from VR3 wiper OVPSET is fed to the OVP trip comparator IC6-A on the
main board via PJ1-18; it is also fed to the ADC input via divider R37,41 for display of preset over
voltage trip level.
The output on-off switch connected at SW1 drives the output off-on control line OPON bar
providing off-on control at the main PCB via PJ1-33.
The two 4-digit LED displays are driven by IC1 via the segment latch IC10 and the digit latch IC7.
Digit current is provided by IC8 and individual segment current is limited to 50mA by the resistors
R1 to R8. The digit multiplex rate is 2ms and is controlled by IC1 which also provides the inter
digit blanking to prevent ghosting segments.
The power supply for all the above circuitry is provided by the main board.
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