Bias Adjustment; Vc Reading Adjustment; Ic Reading Adjustment; Temp Pa - Furuno FS-1575 Service Manual

1. Bias adjustment

For the adjustment procedure, refer to information on page 5-35. To make check or
adjustment of bias current, be sure to disconnect the [TX OUT] connector from the TX
board.
Use "R51" to make adjustment so that the bias current will come to 400 mA.

2. VC reading adjustment

For the adjustment procedure, refer to information on page 5-36.
For example, use "R47" to make adjustment so that VC reading displayed on the RT
window or on the TONE TEST window will come to the voltage (42V) between the
collector and emitter of the PA transistor when selecting [MENU] -> 1.TEST -> 3.
TONE TEST.

3. IC reading adjustment

For the adjustment procedure, refer to information on page 5-37.
For example, use "R41" to make adjustment so that IC reading displayed on the RT
window or on the TONE TEST window will come to the collector current of the PA
transistor when selecting [MENU] -> 1.TEST -> 3.TONE TEST.
Concretely speaking, insert a DC ammeter in the 42V power supply line of the PA board,
and then make measurement of PA IC.

4. TEMP PA

When PA board temperature remains at the threshold for a period of one minute or more,
TX output power will automatically reduce and output an error message saying
"ERROR: Tx power reduced. Main AMP heated."
Less than 77°C
77°C to 84°C
84°C or above
Note)
Output power will reduce when any of temperatures detected by the PA-1, PA-2, and
DRV boards remains at the threshold for a period of one minute or longer.
CONFIDENTIAL (internal use only)
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.
FS-5075
Hi MID LOW1
MID MID LOW1
LOW1 LOW1 LOW1
LOW2 LOW2 LOW2
7-24
7.2 Transmission Circuit
FS-2575
LOW2 Hi MID
LOW2 MID MID
LOW2 LOW LOW
LOW2 LOW LOW
LOW
LOW
LOW
LOW