Troubleshooting For Tune Ng - Furuno FS-1575 Service Manual

6.9.3 Troubleshooting for TUNE NG

Causes of "TUNE NG" (tuning failure) are supposed that RF signal is not inputted in
the ATU, the impedance of an antenna is extremely high or low, and the ATU has a
trouble.
1. Is the LED "CR10 (CPU RUN)" on the COUP board blinking? If NOT, the COUP
board has a trouble. Replace the COUP board.
2. Conduct tuning operation. If the ATU shows no reaction to it, check for the
connection between the ATU and the FS-xx75T unit, and check whether power is
supplied to the ATU.
3. Select [MENU] -> 9.SERVICE -> 3.RT SETUP -> 1.SETUP -> "TX TUNE," and
ensure that "TX TUNE" is set to "ON."
4. Select [MENU] -> 1.TEST -> 2.TX SELF TEST -> "COUPLER." If the coupler
fails the self-test, check for the connection between the ATU and the FS-xx75T unit
5. Conduct tuning operation. If the ATU shows no reaction to it, cause a short circuit
between #7 (TUNE OK) and #9 (TUNE) of TB6 on the T-IF board. If "TUNE OK"
appears on the window, the ATU or control cable has a trouble. If "TUNE NG"
appears on the window, the T-TF, MOT, or T-CPU board has a trouble.
6. If "TUNE NG" appears on the window as soon as tuning operation is initiated, the
RF signal has not been inputted. In this case, check for the coaxial cable between the
ATU and the FS-xx75T unit. TX output power for tuning operation ranges from 10
to 15 watts. Ensure that it has fallen within the said range. Furthermore, check
whether the volume of TUNE POWER Data has been reduced.
7. Conduct tuning operation. If the system initiates tuning and fails it in a specific
frequency band,
1) check for any burnout in the matching circuit;
2) conduct a self-test on the ATU and check for any relay with burned out contact;
3) check whether the antenna is breaking or touch with a structure;
4) ensure that the ground wire of the ATU is securely connected;
5) ensure that the shield side of the RF coaxial cable to be connected to the ATU is
securely connected to the COUP board;
6) ensure that the connector of the RF coaxial cable to be connected to the ATU is
securely mounted;
7) ensure that RF coaxial cable to be connected to the ATU has no corrosion or
water leakage; and
8) change the length of the antenna lead-in wire.
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This confidential document is used only by FURUNO authorized persons.
It is strictly prohibited to reproduce the document in whole or in part without prior written permission of FURUNO.
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6.9 Checking Antenna Coupler