Zenith XBV 443, Service Manual

Page: 48 / 108

3-57
IC603
Flash
ROM
IC501
Front
µ
-com
IC601
(27Mhz)
MRESET
WE
VCC
data
address
IC601
MPEG
(STI5589)
1) MPEG IC start oscilating(27Mhz) after being
installed VCC
2) MPEG IC is initialized by MRESET
3) MPEG IC send the WE(read/write) signal before
communicating with FLASH ROM
WE signal should be confirmed by Flash or the
next step will not continue.
As that result, the initial step(power cord in ->
green LED -> red LED -> standby) will fail.
If WE signal doesn’t appear, check the VCC and
replace the Flash ROM…
VCC
Power
Cord in
MRESET
WE
3. Initializing between MPEG and Flash
VCC (3.3V)
V_REFD (2.1V)
9 PIN
10 PIN
IC202
DSP
(STL6317)
1) There is one kinds of reference voltage on DSP
IC
2) These are outputed from DSP IC and 2.1V is
used as reference of Pick - up
If these reference voltage don’t appear, All kinds of
servo control will fail.
So, should be checked first of all Check the DSP
IC and replace…
3) The reference voltage of DSP is 1.65V for inside
of IC L6317, but we can cheek the voltage only
by TP.
VCC
3.3V
2.1V
Power
Cord in
V_REFD
4. Reference Voltage 1