JRC JMA-5212-4, Service Manual

Page: 149 / 172

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6.3.2. External Equipment
Connection cannot be established with external equipment for NMEA output.
Description
The following may cause this trouble: connection polarity, baud rate setting, setting for using
external navigator, or output-equipment fan failure.
Location of cause
o
Procedure
Polarity If the connection is correct, the output is LOW at the time of no signal
when viewed with the negative side as reference on the oscilloscope.
Baud rate Adjust the baud rate to the value defined in the output specifications for
the navigator.
Output-equipment fan
failure
Check that multiple devices are not connected to the same port on the
external equipment. Signals may not arrive correctly because the
output capacity of the external equipment is exceeded. Follow the
external equipment specifications.
The true bearing value cannot be displayed correctly.
Description
The setting may not be correct, or the bearing sensor may have a problem.
Location of cause
o
Procedure
Setting The GYRO I/F circuit may not be set correctly.
Check if the setting is suitable for the equipment in use.
GYRO(DATA)
Step type
If signal amplification is too low when a step-type gyro is used, an error
may be posted. In many cases, the error can occur if the multiple
devices are connected with the same port and the output capacity of the
gyro compass is exceeded.
In only a few cases, electric potential at LOW level of the output signal
increases at that time. To conform to the input specifications for the
GYRO I/F circuit, voltage at LOW level must be
r
2.5 V or less. Voltage
at HIGH level must be
r
20 V or more.
GYRO(DATA)
Synchro type
If an error occurs intermittently, it may be improved by setting DIP-SW
S4 No. 5 on the GYRO I/F circuit to ON. However, note that the setting
of S4(5) simply extends time for error determination and does not solve
the essential problem of the gyro.