Kenwood NX-1200 Series, Service Manual

Page: 47 / 86

(No.RA077<Rev.001>)1-47
5.1.6 Inspection Procedure
- There is problem with circuit
inside BLS.
- Need to replace to new PCB.
●Check VCO control voltage at point
B
- In case of assist tuning value is [1],
the voltage is about 0.04V;
- In case of assist tuning value is [256],
the voltage is about 4.9V.
- Remove R27 .
- Measure the voltage
at point
A
.
●Check VCO output level
- Remove
R9 .
- Solder the following capacitor on the
position
C
($C89) .
CK73HB1H471K for NX-1200
CC73HCH1H470J for NX-1300
- Observe the Signal at
TL2 with
spectrum analyzer through high
impedance probe.
●Check Assist voltage supply circuit
- Solder back
R9 and remove capacitor
at position
C
.
- Measure the voltage at point
A
by
manually setting assist tuning value
[256].
●Observe the Signal at TL2 with
spectrum analyzer through high
impedance probe.
- Check 5C supply
circuit outside BLS.
Assist Auto tune
No Signal
Signal exists
- There is problem with circuit
inside BLS.
- Need to replace to new PCB.
- There is problem with circuit
outside BLS.
- Check power supply circuit.
Short Circuit
Voltage is 0V. Voltage is 0V.
- There is problem with circuit
outside BLS.
- Check power supply circuit.
- There is problem with circuit
inside BLS.
- Need to replace to new PCB.
- There is problem with circuit
inside BLS.
- Need to replace to new PCB.
- There is problem with circuit
outside BLS.
- Please check
IC2 operation.
- There is problem with circuit
outside BLS.
- Please check
IC5 operation and
MPU/DSP IC501 pin18 for VCO
control voltage detection.
Voltage varies when
tuning digit change.
5C OK
5C NG
Signal Frequency remain same when tuning digit change.
Voltage varies when
tuning digit change.
When the mentioned condition is not satisfied.
The voltage change when the assist tuning digit change.
NG
Signal Frequency change
when tuning digit change.
- Remove R59 and C42
for NX-1200.
- Remove
L21 and C42
for NX-1300.
- Check whether
TL2 is
short circuit.
OK