58
5 Trouble Shooting.
UUT Problem
Possible Causes
Further Checks
UUT will not switch on
from EXT DC source.
EXT DC adapter o/p out of spec.
EXT DC Fuse Blown.
PSU Board fault.
Measure o/p.
Check Fuse.
Swap or test PSU Board.
If unit can be powered from a
battery source then a fault exists
in the external DC detect
circuitry on the PSU Board.
UUT will not switch on
when powered by
Battery.
Battery discharged.
PSU Board fault.
Measure terminal voltage of
battery.
Swap or test PSU Board.
If unit can be powered from
mains then fault lies on PSU
Board Between the Battery and
the input to IC7. Check
DC_Battery Signal is available to
the PIC and confirm operation of
USE_Battery switch TR2.
Unit will not switch on
from either Battery or
EXT DC source.
On/Off switch faulty.
+5VD supply low.
PIC Processor not running.
Try turning unit on by pressing
the rotor switch. If UUT switches
on check On/Off signal from
Switch Board to PSU Board.
M5VD supply on Host
Comms ConVE Pin 4, -
VE Pin 1 and confirm is in spec.
Reset PIC by linking Pin 8 to Pin
1 on the Host Comms port
momentarily. Then attempt to
power on UUT.
No Keyswitch response.
Switch Board failure.
Main Board failure.
Swap or test Switch Board.
Swap or test Main Board.
No Rotor response.
Rotor failure.
Switch Board failure.
Main Board failure.
Test Rotor operation.
Swap or test Switch Board.
Swap or test Main Board.
When Rotor is revolved
menus are skipped.
Rotor failure.
Switch Board Failure.
Swap or test Rotor Switch.
Swap or test Switch Board.
Pressing Rotor Switch
fails to switch on unit but
menu selection is
possible.
PSU Board.
Switch Board.
Swap or test PSU Board.
Swap or test Switch Board.
(Probable D3 O/C)