Furuno FR-2155, Service Manual

Page: 26 / 152

2-12
2.9 Tuning Indication
The tuning indicator extends more than 80% of its full length on all ranges at best tuning. The
self-test result display reads the tune indicator voltage.
2.10 Manual Tuning
When tuning mode is changed from auto to manual mode, the tuning control voltage (a) found in
full search is selected. In manual tuning mode, the graphical tuning control voltage indicator
appears under the tuning indicator. The minimum scale is 2 V and the maximum scale is 32 V.
2.11 Tuning Circuit
Figure below shows the tuning circuit. Tune control voltage is output from P551, A25 on the
SPU board.
Figure 2.7 Tuning Circuit
GA
U35
GA
U44
ENC-
ODER
U44
D/A
CONV. B21
A25
U62
x1
F VT
0 to 5 V
#10 #8
#1 #3
x6
C VT #12
#14
U94
SUM
TUNE CONT.
(To MOTHER Board)
FR2115-SME-10B
P551
P551
U94
U94
B22
TUNE ENC A.
(From MOTHER Board)
TUNE ENC B.