Kenwood NXR-700H Service Manual page 97

1-2. Hardware Traceability (Method 1)
■ Procedure for IC703 (Main MPU) traceability
Power Source Voltage
Test Point Normal Output Voltage
IC329 (pin 4) 3.3VDC
IC306 (pin 3) 1.5VDC
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) 3.3VDC
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) 1.5VDC
IC15 (pin 3) 3.3VDC
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 3.3VDC
(either end of R521 is OK)
Correct condition
Parts other than IC324 are malfunctioning.
TROUBLE SHOOTING
Abnormal
condition
Abnormal
condition
Abnormal
condition
Abnormal
condition
Abnormal
condition
Abnormal
condition
NXR-700H
Confi rmation of IC329 (pin 5) output
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.
If 25.8048MHz oscillation cannot be confi rmed:
X700 is malfunctioning or a component around
X700 is malfunctioning.
Clock oscillation amplitude is weak:
The drive circuit for IC703 is malfunctioning.
Check the voltage of pin 1 and pin 2 of IC726:
Pin 1 = 3.3VDC. If not, IC325 is malfunctioning.
Pin 2 = 3.3VDC. If not, IC708 is malfunctioning.
Confi rmation of IC307 (pin 1) output
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.
If 12.288 MHz oscillation cannot be confi rmed:
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
IC325 side:
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.
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