Kenwood NXR-700 Service Manual page 42

NXR-700
1-2. Hardware Traceability (Method1)
■ Procedure for IC703 (Main MPU) traceability
Power Source Voltage
Test Point Normal Output Voltage
IC329 (pin 4)
IC306 (pin 3)
Correct condition
Confi rmation of Clock frequency
Test Point Proper Frequency
R725 25.8048MHz
(either end of R725 is OK)
Correct condition
Confi rmation of Reset control
Test Point Normal Voltage
IC726 (pin 4)
Correct condition
Parts other than IC703 are malfunctioning.
■ Traceability Procedure of IC324 (TX Vocoder_DSP)
Confi rmation of Power Source Voltage
Test Point Normal Output Voltage
IC307 (pin 1)
IC15 (pin 3)
Correct condition
Confi rmation of Clock frequency
Test Point Proper Frequency
R679 12.288MHz
(either end of R679 is OK)
Correct condition
- Confi rmation of Reset control
Test Point Normal Output Voltage
R521
(either end of R521 is OK)
Correct condition
Parts other than IC324 are malfunctioning.
42
TROUBLE SHOOTING
3.3VDC
1.5VDC
3.3VDC
1.5VDC
3.3VDC
3.3VDC
Abnormal
Confi rmation of IC329 (pin 5) output
condition
Remove R711 and R721.
If the voltage is 3.3VDC, IC703 is malfunctioning.
Confi rmation of IC306 (pin 3) output
Remove R715 and R716.
If the voltage is 1.5VDC, IC703 is malfunctioning.
Abnormal
If 25.8048MHz oscillation cannot be confi rmed:
condition
X700 is malfunctioning or a component around
X700 is malfunctioning.
Clock oscillation amplitude is weak:
The drive circuit for IC703 is malfunctioning.
Abnormal
Check the voltage of pin 1 and pin 2 of IC726:
condition
Pin 1 = 3.3VDC. If not, IC325 is malfunctioning.
Pin 2 = 3.3VDC. If not, IC708 is malfunctioning.
Abnormal
Confi rmation of IC307 (pin 1) output
condition
Remove R486 and if 1.5VDC, IC324 is malfunction-
ing.
Confi rmation of IC15 (pin 3)
Remove R488 and if 3.3VDC, IC324 is malfunction-
ing.
Abnormal
If 12.288 MHz oscillation cannot be confi rmed:
condition
X300 is malfunctioning or a component around
X300 is malfunctioning.
The clock oscillation amplitude is weak.
The drive circuit for IC324 is malfunctioning.
Remove R521 and then measure the voltage of
Abnormal
IC325 side:
condition
If not 3.3VDC, IC325 is malfunctioning.
Remove R521 and confirm the voltage of pad
side of IC325:
If the voltage is 3.3VDC, IC324 is malfunctioning.