Akai PDP4216M, Service Manual, Page: 73 / 86

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3-4. TCP damage
(1) In case of shorting or opening of IC output of TCP several
vertical lines occured.
O
Test Point: Enlarge the after measuring output TP of
GND~TCP.
O
Waveform state: As shown Output of (Fig. 8)
In case of normal wave output, when STB signal is
applied, STB signal remains High. And when STB signal
is applied again, it must be fall Low.
But when TCP IC is bad, even STB signal is not
generated, Output falls to Low.
[
Since the output TP of TCP is covered with SR, when
measurement is needed, remove the SR, measures. And
after measuring insulates TCP leads with insulation tape.
(2) In case of being damaged on TCP IC, the screen doesn’t
be shown or happens discharge partially. When IC fail
occurs, it will be able to discover the trace which is burned.
O
Test Point: Enlarge the after measuring output TP of
GND~TCP
O
Waveform state: Output wave doesn’t come out
O
Measurement position: Enlarge the after measuring
output TP of TCP (Full White Pattern)
3-5. Crystal(CTRL B/D: X2) damage
(1) When Crystal is damaged, the screen doesn’t be turned
on.
O
Test Point: Measuring 3pin of GND~Crystal(Ctrl B/D: X2)
O
Waveform state: Output wave doesn’t come out
(2) In case of unusual launch of the Crystal, it may blink the
screen.
O
Waveform state: As shown (Fig. 9)
O
Measurement position: Measuring output 3pin of
Crystal(X2: 100MHz) on Ctrl B/D (Full White Pattern)
(Fig. 8) When IC output of TCP is poor
<TCP Normal Output Wave >
Output voltage of the signal is dropped
(Fig. 9) When Crystal is bad
<Crystal Normal Output Waveform >
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