RFL 9785
RFL Electronics Inc.
June 18, 2009
18-5
(973) 334-3100
To protect the 5 Vdc output from excessive output currents, the voltage across shunt R26 is monitored
between pins 2 and 3 of U3. Like the voltage feedback path, exceeding limits, established by resistors
R35 and R36, causes pin 14 to go high and reduces the output voltage.
Integrated circuits U6, U7, and U8 are series regulators which provide post regulation for the
secondary outputs. Post regulation is required to meet the voltage regulation requirements of the
supply. Feedback for regulator U7 is provided by resistors R47, R25, potentiometer R49, and CR16.
Feedback paths for the other regulators are similarly structured.
All outputs have or’ing diodes. These diodes; CR12, CR15, CR18, CR19, allow two supplies to be
connected in parallel. Feedback signals for all outputs are taken before the or’ing diodes. The
temperature voltage sensitivities introduced by the or’ing diodes are compensated with diodes CR13,
CR16, CR17, and CR6.
18.2.3
CONTROLS AND INDICATORS
Figure 18-2 shows the location of all controls and indicators on the RFL 9785 Power supply module.
These controls and indicators are described in Table 18-2. DS1 is visible with the RFL 9785 Power
supply module installed in the chassis. All other controls and test points are only accessible when the
module is removed from the chassis or is on a card extender.
Table 18-2. Controls and indicators, RFL 9785 power supply module
Component
Designator
Name/
Description
Function
DS1
LED indicator (green)
ON/OFF power indicator
R44
Potentiometer
+5 Vdc adjust (for factory use only)
R49
Potentiometer
+15 Vdc adjust (for factory use only)
R50
Potentiometer
-15 Vdc adjust (for factory use only)
TP1
Test point
Power supply common
TP2
Test point
+5 Vdc
TP3
Test point
+15 Vdc
TP4
Test point
-15 Vdc
TP5
Test point
+12 Vdc