41
VSX-
8
21-K
5
6
7
8
5
6
7
8
A
B
C
D
E
F
Is the voltage 5
V
?
Is the voltage 1.8
V
output?
Is REG1 abnomally hot?
Is pin 4 (en) of IC805 low?
Yes
Yes
N
o
N
o
5
V
input
1.8
V
output
The output and G
N
D may be
short-circuited. Check the path
between them.
REG1 (pin 3)
REG1 (pin 2)
Yes
Is the voltage 5
V
input?
Is the voltage 5
V
output?
N
o
Is pin 8 (fault) of IC805 high?
N
o
Yes
Yes
Yes
Yes
Yes
OK
Yes
Yes
Yes
5
V
input
IC805 (pins 2, 3)
USB bus power
IC805 (pins 6, 7)
Check the pattern in the path.
N
o
Check the parts and pattern in the
path of C
N
801.
N
o
DATA and ADDRESS lines
between SDRAM (IC803),
FLASH ROM (IC802), and IC801
are may not be connected.
Check the C
N
704B of CPU Assy
and C
N
704A of FRO
N
T Assy.
Check the parts and pattern in the
path. Replace XTAL1, etc..
Operation of IC801 is OK.
Go to step 3.
Operation of IC801 is OK.
Go to step 3.
D+ and D- should have waveform
during normal condition. Check the
pattern in the path of IC801. etc..
N
o
Check the pattern in the path.
N
o
Replace REG1.
Replace IC805.
D
To Step 2
Step 2: Operation of USB Media Control IC
IC801 (pins 54, 55)
C
N
802 usb_rx,tx (pins 4, 5)
Yes
JACK801 (pins 2, 3)
IC801 (pin 44) -> IC803 (pin 38)
Is there a 12 MHz output?
CP803 pins 1, 2 (reset,rdy)
is high?
Are there the waveforms
like figure?
After turning the power on and
several seconds later,does SDCLK
change 12 MHz to 80 MHz?
N
o
N
o
N
o
usb_rx and usb_tx should be high
during operation. Check the
pattern in the path of FRO
N
T and
CPU Assys.
N
o
Check the path to CPU Assy.
N
G
xin/xout
initial communication [SDCLK]
Do usb_rx and usb_tx
communication
with main micom?
Fig. D+
X: 1
μ
S/div, Y: 2
V
/div
X: 1
μ
S/div, Y: 2
V
/div
Fig. D-
Summary of Contents for VSX-521-K
Page 13: ...13 VSX 821 K 5 6 7 8 5 6 7 8 A B C D E F ...
Page 17: ...17 VSX 821 K 5 6 7 8 5 6 7 8 A B C D E F D MAIN ASSY C AMP ASSY D MAIN ASSY E SUBWOOFER ASSY ...
Page 21: ...21 VSX 821 K 5 6 7 8 5 6 7 8 A B C D E F ...
Page 22: ...22 VSX 821 K 1 2 3 4 A B C D E F 1 2 3 4 4 5 D MAIN BLOCK DIAGRAM for VSX 921 K T D MAIN ASSY ...
Page 23: ...23 VSX 821 K 5 6 7 8 5 6 7 8 A B C D E F ...
Page 27: ...27 VSX 821 K 5 6 7 8 5 6 7 8 A B C D E F only P CPU ASSY Not used ...
