Codan NGT 2010 RF Technical & Service Manual page 792

Fault finding
Finding faults within the split-site remote control system requires the full system to be
connected together.
The types of faults that can occur are:
•
•
•
Voltage measurements
The circuit diagrams and the relevant circuit notes give voltages at various points under
various conditions and are useful for locating the faulty section of the remote control
equipment.
The parameters listed below should always be checked first.
Drawing
Table 7: Supply voltages for the Backplane PCB
Supply
A rail
+5 rail
Drawing
Table 8: Supply voltages for the Microprocessor & TCVR Interface PCB
Supply
B rail
+5 V
2.5 V
5 V ref
NGT Transceiver System Technical Service Manual
no reception, with or without signalling
no transmission, with signalling
no signalling
08-05995
Description
Unregulated DC supply
+5 V regulated supply
08-03993
Description
+10 V regulated supply
+5 V bias supply
+2.5 V bias supply
+5 V reference for ADCs
Voltage
14 V nominal
5 V ±0.4 V
Voltage
10 V ±0.2 V
5 V ±0.5 V
2.5 V ±0.25 V
5 V ±0.2 V
8571—Fault finding
Source
external transceiver in
12 V systems
IC1
Source
IC10
junction R44/R45
junction R34/R35
V5/R42
353