Tait TB7100, Service Manual

Page: 220 / 370

222 Transmitter Fault Finding (25W) TB7100 Service Manual
© Tait Electronics Limited October 2005
13.1 Power Supplies
Introduction
First check that a power supply is not the cause of the fault. There are two
power supplies and a switch circuit for the transmitter:
■
Task 1 : 13.8V DC supply from power connector ( +13
V
8
BATT
)
■
Task 2 : switch circuit for 13.8 V DC supply
■
Task 3 : 9 V DC supply from 9V regulator in PSU module ( +9
V
0
TX
)
The measurement and test points for diagnosing faults in the power supplies
are summarized in
Figure 13.1 .
Figure 13.1 Measurement and test points for diagnosing faults involving the power supplies for
the transmitter
GND
TEST POINT
GND
TEST POINT
9V0 TX
TEST POINT
9V0 TX
TEST POINT
SIGNAL TYPES
RF
ANALOG
EXCITER PAs
FRE-
QUENCY
SYNTHE-
SIZER
OTHER
TRANS-
MITTER
CIRCUITRY
TRANSMITTER
INTERFACE
CIRCUITRY
DRIVER
+13.8 V DC SUPPLY
TO PA DRIVER
+13.8 V DC SUPPLY
TO PA DRIVER
+13.8 V DC
SUPPLY TO PAs
+13.8 V DC
SUPPLY TO PAs
L310
POWER
SUPPLY
AGND
+9V0 TX
+13V8 BATT
SWITCH
L306