0411 (2Sc4288A) Damaged Due To Surge Voltage - Tatung OMNISCAN SERIES Service Manual

6.7 0411 (2SC4288) DAMAGED DUE TO THE SURGE VOLTAGE
TAKE OUT 0411
FROM MAIN BOARD
& POWER ON
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INPUT 64KHz
SYNC. SIGNAL
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CHECK VOLTAGE
------------------------>
0611, R666, D608, D606
SUPPLY CKT.
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CHECK PWM
---------------------------->
PIN 2 OF T600
GENERATOR SOUARE WAVEFORM
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20Vp-p
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NO .
L _________________________________
>
R607, 0607, 0608, 0606a
: 0602, 0601, D600, 0603, 0605
I~ D~,~OO,D~,OOOO
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CHECK FEEDBACK
---------------------->
USING 16V VOLTAGE TO SIMULATE
CIRCUIT THE FEEDBACK VOLTAGE (ON PIN 3 OF 0620a)
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MEASURE THE WAVEFORM (PIN 2 OF T600)
THE WAVEFORM WILL CHANGE WHEN
: 16V (VIA 10Kohm RESISTOR) TOUCH PIN 3 OF 0620a.
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NO
r--------------------------------->
0620a, 0620b, R602, D601
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YES
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CHECK HOR. DEF.
---'---------------------->
H. DY, L402, L405, C428
CIRCUIT C429, C430
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CHECK DPC BOARD ----------------------> GROUNDING TRACK
PWB-1732
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CHANGE A NEW
2SC4288A
AND POWER ON
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END
IF BREAK, THE PARABOLA SIGNAL
WILL GET TO H1, H2 SIGNAL LINE
VIA PINS 5,6 OF P310
THIS WILL CAUSE THE HOR. OSC
UNSTABLE AND DAMAGE THE 0411.
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6-7
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