Zenith XBV 443, Service Manual

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3-59
Check the followings
1) Check the video output mode. if the output mdoe is progressive - on, there is no composite signal.
the output mode should be changed to progressive - off
2) Check the buffer IC and MPEG, and then replace.
Composite out
34 pin(IC601)
35 pin (IC601)
27 pin(IC601)
23Pin(IC609)
4Pin(IC609)
VCR Block
buffer
IC609
IC601
STI5589
(MPEG)
7. Checking the Video Signal
81
36
DSP-RST
PC[o]
IC202
DSP IC
IC203
MOTOR
AMP IC
IC601
MPEG
Let’s look over the initial step of DSP
1) First. DSP IC receive the DSP - Reset from
MPEG
2) This reset signal get DSP initialized and DSP is
ready to do first step for servo
3) PC[o] from DSP is the test signal for checking
the PLL- loop
4) after checking the PLL-loop, the second step is
followed. the second step will be explained on
next page…..
if PC[o] doesn’t appear, check DSP and
replace.
/DSP-Reset
Vcc(3.3V)
50ms
DSP Reset period
PC[o]
8. Checking the first step of servo (1)