Codan NGT 2010 RF, Техническое и сервисное руководство

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NRI—Fault finding
280 NGT Transceiver System Technical Service Manual
Testing the NRI Microcontroller PCB
A number of test points are provided on the NRI Microcontroller PCB to enable
measurements to be made that assist in fault finding. A multimeter and an oscilloscope
(if available) may be used to measure the signals at each of these test points.
Table 8
shows the expected signals at the test points. If these signals fail to meet specification,
Table 8 provides the possible causes of the fault and the action required. It is important
that each test point be measured in the order that they appear in Table 8 .
Drawing 08-05854 (sheet 1)
Table 8: Test points on the NRI Microcontroller PCB
Test point Description Acceptable
signal/level Possible fault causes Action
+5 V Reg5 V
supply rail +5.0 V
±
0.1 V No power input Check for +12 V
across C139
Failed switchmode
controller Replace PCB
Failed
microcontroller, RAM
or ROM chip Replace PCB
+10 V Reg10 V
supply rail +10.0 V
±
0.1 V Failed regulator Replace PCB
Failed analog
component(s) Replace PCB
16 MHz Clk Microprocessor clock
signal
16 MHz
±
100 Hz
5 V p–p square wave
Failed microcontroller Replace PCB
RESET Active-high system
reset signal Logic-low just after
system power supply
connected Failed microcontroller Replace PCB
Corrupted program
code Replace PCB
+5 VQ Reg5 V quiet
supply +5.0 V
±
0.1 V Failed analog
component(s) Replace PCB
RX_AF1 CIB receive audio
path 1 +5.0 V
±
0.1 V with
no audio present
Failed analog
component(s) Replace PCB
TX_AF CIB transmit audio
path +5.0 V
±
0.1 V with
no audio present
Failed analog
component(s) Replace PCB
Failed Vocoder PCB See Table 9
AUD– CIB system
audio – +5 V with
∼
6
µ
s wide
5 V p–p low-going
pulses every 80
µ
s
Failed programmable
logic device Replace PCB
Failed analog
component(s) Replace PCB
Firmware failure Attempt to
reprogram if
possible