Sailor RM2042 Technical Manual page 33

3 SERVICE
3.4 TROUBLE SHOOTING
Trouble shooting should only be performed by persons with sufficient technical knowledge, who have the
necessary measuring instruments at their disposal, and who have carefully studied the operation
principles and structure of the VHF DSC RM2042.
The first thing to check is whether the fault is somewhere in the antennea circuit, the power source, the
handset, or inside the RM2042 it self.
In order to help you during trouble shooting, the section 5. CIRCUIT DESCRIPTION AND SCHEMATIC
DIAGRAMS contains diagrams, principal descriptions, and drawings showing the location of the
individual components. Typical values for the DC and AC voltages are indicated in the diagrams, and also
the test points are indicated in the diagrams.
The RM2042 has a number of trimming cores and trimmers, which must not be touched unless
adjustments as specified in section 3.6. ADJUSTMENT PROCEDURE can be made.
When measuring inside the unit, short circuits must be avoided as the transistors would then be spoiled.
3.5 PERFORMANCE CHECK
CHECK OF SYSTEM PERFORMANCE
With this check procedure it is possible to control the performance of a hole VHF DSC system, which
include the DSC unit it self, the VHF tranceiver, a GPS receiver and a printer.
The idea of this test procedure is first to key-in a call sequence and hereby control the connections to the
key board and display, and the function of these modules. The next step is to send the DSC call to your
self, which is done in the 'CALL' menu by keying-in the MID-number of the unit it self. The DSC call is now
generated by the microprocessor and the FSK encoder at the receiver module. The FSK signal is then
modulating the connected VHF radiotelephone and a short piece of wire connected to the antenna
terminal at the VHF will be sufficient to transfer the RF-signal to the channel-70 receiver. The received
signal is then demodulated, decoded, sampled and finally recognized by the microprocessor. As a
response to the receiption of the call, the microprocessor will write the received message to the printer
and at the same time generate a gated tone sequence for the internal loudspeaker.
The primary force of this test is that the function of all modules is controlled and that the connections for
external equipment are checked as well. An other force is the fact that the test procedure does not require
any test equipment.
The check procedure can also be used as a function check after the system has been installed.
1. Connect the RM2042 to the VHF tranceiver, the printer and the GPS receiver (if available)
2. Select the 'FUNC' menu and then the 'Position' menu. Control that the position data is updated by
the GPS receiver.
3. Select the 'CALL' menu and press the 'up-arrow' button to key-in the MID-number of the DSC unit
it self.
4. Press 'NEXT' and select 'Position' by means of the 'left-arrow' and the 'NEXT' button.
5. Press 'NEXT' and 'SEND' for transmission of the DSC call.
6. The DSC call should now be received by the RM2042 and the alarm signal will be heard in the
internal loudspeaker. The RM2042 will write the received message to the printer.
9403
RM2042
PAGE 3-3