Denon AVR-4520CI Service Manual page 115

5.2. USB device is not recognized
Are the USB port settings correct?
Are you using a USB hub?
Is the USB device compatible with the set?
Is the wire properly connected between N603 and N801?
Is a voltage (5V) being supplied between pins 1 and 4 of N601 (back
panel USB connector) and N603 on the USB B'D circuit board (front
panel USB connector)?
Is the USB device not recognized for both the front and rear
connectors?
YES
The circuitry from U503 or U503 to U606 are defective.
Checking the settings
YES
Checking the USB device
NO
YES
Checking the set (AVR-4520)
YES
YES
Rear is not recognized
Front is not recognized
NO
Set the front and rear properly.
YES
Don't use the USB hub.
Only mass storage devices in FAT16 or
NO
FAT32 formats or MTPcompatible devices
and iPod (except some models) are
supported.
NO
Connect the wire properly.
NO
The U603 and U604 periphery circuitry is
defective.
The circuit from U604 to N601 is defective.
The circuitry from U603 to N602 on the USB
B'D circuit board is defective.
115