Pulsar LPA100, System Manual

Page: 51 / 66

Chapter 7 Power Supply Module
June 2001 Page 7–3
7
7.2 Power Supply Circuit
Description
The module comprises the following circuits:
• Fuses
• ON/OFF Switch
• Input Filter
• Power Alarm Failure Relay
• dc/dc Converter (2)
• Output Filter
Fuses
48V 125V 250V
F1, F2 3A 1.6A 3/4A
ON/OFF Switch
S1 - Push-button Switch (DPDT)
When in the “ON” position (pins 1 and 4), dc
current flows through the input filter to the dc/dc
converter.
Input Filter
The input filter (C1, C2, C3) contains zener diodes
(Z1, Z2) that provide protection against surges, a
diode (D1) that provides protection against
reverse polarity, a differential choke XFMR (L1),
and the Red Input LED1.
Power Alarm Failure Relay
This circuit includes:
• K1 - Alarm Relay
• J1 - Jumper (NO/NC)
In versions G01, G02, and G03 the field-selec-
table option can change the alarm contact
de-energized state to NO or NC. (It is currently
shipped in the NC de-energized state, and can be
changed to NO if desired.)
DC/DC Converter
The two dc/dc converters (PS1 and PS2) operate
at a maximum of 1 MHz and, as a result,
switching noise is outside the 30-535 kHz range of
the TC–10B/TCF–10B. The converter outputs,
+20 Vdc and -20 Vdc, is fed to the output filter.
(See Figure 7-3.)
Output Filter
The output filter for the +20 V consists of C4, C6,
C8, and Z4. The output filter for the -20 V consists
of C5, C7, C9, and Z3.
7.3 Power Supply
Troubleshooting
The three test jacks on the control panel:
• TP3 (+20 Vdc)
• TP2 (Common)
• TP1 (-20 Vdc)
can be used to determine if the two voltages (+20
Vdc, -20 Vdc) are present. In addition, the LED2
output indicates that the dc/dc converters are
generating voltage. The LED1 input indicates that
voltage is present at the input of the dc/dc
converter.
For basic troubleshooting, perform the following
procedure:
1. If LED1 is not on with the module de-
energized, remove and check the fuses (F1,
F2) with an ohmmeter.
2. With the module de-energized, check the
ON/OFF switch (S1) with an ohmmeter to be
sure it opens and closes accordingly.
3. If LED2 is not on with the module energized,
check the +20 V and -20 V outputs at TP3 and
TP1, respectively. The one with voltage
absent will require replacement of the associ-
ated dc/dc converter.
!
CAUTION
BE CAREFUL NOT TO MISPLACE SCREWS,
SPRING WASHER OR INSULATING WASHER
USED FOR MOUNTING TRANSISTORS.