LM721A
Service Manual Rev: A
Page
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Page
Page 35
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57
2.)
W / LED , No Backlight
Check Fuse F101 =12V
NG
OK
To change
Check ON/OFF signal
Check Interface board
NG
OK
Check U201 pin9=12V
NG
OK
Change Q201 or Q202
Check the pin1 of U201 have correct wave
NG
OK
Change U201
Check D201(-),D202(-) have the output of square wave at short time.
NG
OK
Check Q205/Q207/Q203/D201
or
Check the resonant wave of pin2 & pin5 for PT201/PT202
NG
OK
Check the output of PT201/PT202
Check Q209/Q210/C213 or
Q211/Q212/C214
Check connecter & lamp
OK
NG
Change PT201or PT202
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