Fault Diagnosis - JVC KD-R491 Schematic Diagrams

5.2

Fault diagnosis

No Power
10A Fuse
NO
IC901
(BU_DET)
NO
IC901
(ACC_DET)
NO
D861/ R1080
Open?
NO
IC891 Pin6
5.2V?
YES
IC901 Pin15
3.3V?
YES
IC851 Pin5
1.2V?
YES
Re-program ROM
YES
Replace New 10A Fuse
YES
IC901 Pin 7 & 8 supply must keep above 7.5V,
Check D903, D902, C919 & C918.
YES
Check pattern and component between
CN990 Pin13 to IC901 Pin6.
YES
Replace Component
IC891 Pin3
NO
3.3V?
YES
IC891 Output
Short Circuit
NO Check the component connected to
IC901 Pin15, maybe shorted.
IC851 Pin1 /
NO
Pin3 3.3V?
NO
Check the component connected to
IC901 Pin11, maybe shorted.
(No.MA665<Rev.001>)29/33
NO
Check R705 Open
Check the component connected to
YES
IC851, maybe shorted.