Kenwood NX-3220 K Service Manual page 161

5.5 Failure diagnosis of the VCO section (NX-3320)
[Overview]
The VCO circuit is mounted inside the BLS. BLS stands for "Board Level Shield".
This BLS has no lid and provides high shielding performance. Because BLS is difficult to solder, components inside the BLS can't be
soldered.
When there is a problem with the VCO circuit, the VCO can't be repaired.
If the VCO function doesn't work, use this flow chart to identify the problem.
The following is explained about failure diagnosis of VCO circuit inside a BLS<E101>.
[About a BLS]
BLS is shielding case
BLS for VCO area is integrated type and can not be removed
[Prediction problem related to the VCO circuit]
• PLL Unlock
<Radio state>
- Unlock beep
- VCO Assist voltage tuning is impossible
<The cause>
- VCO control voltage is abnormal
- VCO Assist voltage is abnormal
- VCO power supply is abnormal
- VCO signal output circuit is abnormal
[VCO circuit inside a BLS<E101>]
R 1 0 2
0
$Q101
R106
10
C104 100p
C 1 0 5 1 u 50
IC101
EM6M2
OPA 170AIDRLR
IN+
V+
V-
IN-
oUT
R108
C103 33p
R105 1 0 M
1 2 0 k
[J] [C]
ASSIST
[E]
IC102
BU7295HF V
CV amp
IN+
VDD
VSS
R112
IN-
oUT
1k
C106
0.1u
[D]
LB73H0AY-0 04
L121 L131
R126 R 1 2 8
R127
1 0 0 n
0 0 3 9 0
(H0AM)
(D)
VCOL
Q102
L151
100n
(H0AM)
C N 1 0 1 50C
Q113
2SD2654/W /
VCO circuit inside a BLS (in a dotted line)
$C114 C134
2p
VCOH (B)
BB555-02VH
C142
C133 D134 C136 4p
3p
(B)
1 3 p
(G)
C156
C115 0.5p 4p (B)
(B)
BB555-02VH
C157 C161
C153 D154 3p 9p
(B)
13p
(G)
Overlap
[G]
R142
R124
LB73H0AY-0 04 L112
22k
2 2 k
4.3V
Q114
VT6M1
$Q115
Q116
SSM3K15AMFV
[ I ]
[A]
C145
Q131 1p
(B)
BFU660F (B)
$C180
R135
$C147
8.2
Q151
(B) C166
BFU660F
2.5p
$C179
(B)
R155
4.7
BLS
E101
F1B-0095-0 0
[F]
3.9V
Q112
L111
Q111
VT6M1
LB73H0AY-0 04
RE1E002S P
[H]
(No.RA053<Rev.001>)1-161
Q181
2SC5108FT/Y / C183
3p
(B)
3.2V
[B]
Q103
VT6M1