Service manual

39
VSX-918V-K
5
6 7 8
5
6 7 8
A
B
C
D
E
F
Step 3: Operation of USB Media control IC
Does the
crystal oscillator
at 12 MHz
?
Note: Please confirm it with the USB memory*1 connected for the content.
*1 iPod : This system is compatible with the audio of the following
portable device in Jan. 2008.
5G iPod, iPod nano, iPod nano 2G, iPod nano 3G,
iPod classic, iPod touch
Check CN3*, CN7**
pin 16. [USB XRST]
USBDAO and USBDAI should be
high during operation.
Check the pattern in the path.
Check the MAIN Assy.
Check the parts and patterns in the path.
Replace X402, etc.
No
Ye s
Ye s
Is XRST
high?
No
Ye s
No
IC401 (pins 74,75)
USBDAI, USBDAO (Refer to Fig. 1)
IC401 (pin 44) -> IC461 (pin 38)
XIN/XOUT
* XRST must be high during operation.
Check the MAIN Assy.
Fig. 1
Do
USBDAO and USBDAI
Communicate with
System CPU?
IC401 IC351 (3 V -> 5 V)
USBDAO pin 95 pin 9 pin 11
CN3*, CN7**
pin 19
IC401 IC331 (5 V -> 3 V)
USBDAI pin 96 pin 8 pins 9, 10
CN3*, CN7**
pin 18
IC401
R455 / R456
XRST pin 77
CN3*, CN7**
pin 16
Operation of IC401 is OK.
To STEP 4
Operation of IC401 is OK.
To STEP 4
DATA and ADDRESS lines
between SDRAM (IC462),
FLASH ROM (IC461) and IC401
are may not be connected.
D+ and D- should have
waveform during normal
condition.
Check the pattern in the path.
Check the MAIN Assy.
Replace IC461, IC462. etc.
Are
there the waveforms
like figure?
After
turning the power
on and several seconds
later, does SDCLK change
12 MHz to 80 MHz?
Ye s
Ye s
No
No
CN401 (pins 2,3)
D+/D-
Initial communication [SDCLK]
Fig. D+
X: 1 μS/div, Y: 2 V/div
X: 1 μS/div, Y: 2 V/div
Fig. D-
* VSX-918V (AWX8977)
** VSX-818V (AWX9164)