Inspection Procedure - Kenwood NX-1200 Series Service Manual

5.1.6 Inspection Procedure

Assist Auto tune
NG
●Check VCO output level
- Remove R9.
- Solder the following capacitor on the
C
position ($C89).
CK73HB1H471K for NX-1200
CC73HCH1H470J for NX-1300
- Observe the Signal at TL2 with
spectrum analyzer through high
impedance probe.
Signal exists
●Check Assist voltage supply circuit
- Solder back R9 and remove capacitor
C
at position .
- Measure the voltage at point
manually setting assist tuning value
[256].
Voltage varies when
tuning digit change.
●Observe the Signal at TL2 with
spectrum analyzer through high
impedance probe.
Signal Frequency change
when tuning digit change.
●Check VCO control voltage at point
- 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.
The voltage change when the assist tuning digit change.
- Remove R59 and C42
for NX-1200.
No Signal
- Remove L21 and C42
for NX-1300.
- Check whether TL2 is
short circuit.
- Check 5C supply
circuit outside BLS.
- Remove R27.
Voltage is 0V.
- Measure the voltage
A
by
at point
Signal Frequency remain same when tuning digit change.
B
When the mentioned condition is not satisfied.
Short Circuit
OK
5C OK
5C NG
Voltage is 0V.
A
.
Voltage varies when
tuning digit change.
- 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.
- Check power supply circuit.
- 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.
(No.RA077<Rev.001>)1-47