-41-
PRO
PILOT
725 INSTALLATION & SERVICING MANUAL
1.
The
system
will
not
power
up.
Troubleshooting
Guide
TROUBLESHOOTING GUIDE
In an EMERGENCY
Press
the
OFF
key
to
regain
manual
control.
1. Do not connect or disconnect wiring to the terminal blocks
without first ensuring that the supply is turned off. Certain
components will be seriously damaged if shorted out
inadvertently.
2. When first installing or when changing the wiring always
double check the colour coding before switching on the
power.
3. Do not use a simple voltmeter to attempt to check powered
up Digital logic lines or signal lines unless specifically
described in the following discussion.
4. Ensure that all cable screens are properly earthed.
5. Check the fuses and replace blown ones with direct
equivalents. Most units have one internal fuse, the
Distribution Box has 3.
6. Take suitable precautions when handling PCB’s with Static
Sensitive Devices.
7. Read the ‘Good Wiring Practice’ advice in the ‘Installing Your
Propilot 725’ section earlier.
Faults
Possible cause and remedy.
Check the power supplies to the Distribution Box.
In the Distribution Box PCB:
Check Fuse 1. Check the supplies from the Distribution Box
(Brown and Violet wires at PORT A). Check that the Brown
wire, (normally 4 to 5V) changes to 0V when you try to turn
the autopilot on, if not, then suspect fault in the Distribution
Box.
Check that the Violet wire is normally 0V and changes to +5V
when you try to turn the autopilot on. If this is not so then a
fault with the Distribution Box PCB is likely.
If new software has just been fitted, check the IC legs.
Damaged legs will probably mean a damaged eprom.
General
Principles &
Cautions
