Power Supplies Description; Measurement Points For Frequency Synthesizer Power Supply Circuitry - Tait TM9100 Service Manual

9.2 Power Supplies
First check that a power supply is not the cause of the fault. There are four
Introduction
power supplies for the frequency synthesizer — two are supplied from the
PSU (power supply unit) module and two are produced in the synthesizer
circuitry itself:
The measurement points for diagnosing faults in the power supplies are
summarized in
Figure 9.1 Measurement points for the frequency synthesizer power supply circuitry
FILTERING
FILTERING
OF SUPPLY
OF SUPPLY
FOR PLL
FOR VCO
AND LOOP
CIRCUITRY
FILTER
+5V DEC
PIN 4 OF PIN 4 OF
Q508 Q508
LOOP
VCO FILTER
CIRCUITRY AND
SUMMER
TM9100 Service Manual
© Tait Electronics Limited August 2005
Task 3: 14 V DC supply from SMPS (
Task 4: 6 V DC supply from 6 V regulator in PSU module (+6
Task 5: 5 V DC supply following filtering of 6 V supply (+5
Task 6: 3 V DC supply from 3 V regulator in PSU module (+3
Figure 9.1.
FREQUENCY
SYNTHESIZER
14 V
SMPS
VCL SUPPLY
JUNCTION OF JUNCTION OF
C531 AND R530 C531 AND R530
INVERTER PLL
)
VCL SUPPLY
PIN 4 OF PIN 4 OF
IC606 IC606
+6V0
Q500 AND Q500 AND
R533 R533
PIN 5 OF PIN 5 OF
IC606 IC606
+9V0
+3V0 AN
L506
SIGNAL TYPES
PINS 7 AND 15 PINS 7 AND 15
OF IC503 OF IC503
AGND
Frequency Synthesizer Fault Finding
0)
V
)
V DEC
0 )
V AN
6 V
SUPPLY
9 V
SUPPLY
3 V
SUPPLY
RF
ANALOG
CLOCK
DIGITAL
INTERFACE
CIRCUITRY
173