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4.2 Check OSD, MCU for No OSD Window
Check +5V, ok?
(1) IC1901(OSD IC) pin4 ,6,17
Check IC1901 (OSD IC) pin2,3 have DC 1~3V
with oscillation wave?
Check IC1901(OSD IC) pin5(HBNK)&
pin18(V-), ok?
Check SCL, SDA INPUT, ok?
4.3 Video Board
Caution: Before power on, you must check whether all connectors and components of the set are correct,
otherwise it maybe to destroy the set. There assume that following cases depend on above setup OK. Please
follow as below and check it step by step.
Case 1:No video display on screen
Check IC101 pin 10 (Video Contrast). If it is 0 volt, check IC1901 or maybe IC101 pin 10 short.
Check IC101 pin 18,15,12 If they are 0 volts, replace a new IC to IC101.
Check RGB cathode. If anyone pin is 0 volt, replace a new IC to IC102.
Check IC102 output path. It must be right and without short circuit.
Check G1 voltage. If it is lower equal than -182 volts, check spot killer circuit and check IC801 pin36(Blank).
Check CRT heater. If it is dark, check +6.3v supply voltage of heater.
Replace CRT if it burns out.
Case 2: one or more of R, G, B channel does no display
Check IC101 pin 18,15,12. If anyone is 0 volt, replace a new IC to IC101.
Check RGB cathode. If anyone pin is 0 volt, replace a new IC to IC102.
Check IC102 output path. It must be right and without short circuit.
Replace CRT if it burns out.
Case 3: OSD does not display on screen
Check IC101 pin 1,19,20. If they are 0 volt, check IC101 and IC1901.
Case 4: No video display on screen, but OSD can display on screen
Check IC101 pin 10 (Video Contrast). If it is 0 volt, check IC1901 or maybe IC101 pin 10 short.
4-2
Check OSD, MCU
for no OSD window
Start
YES
YES
YES
No Copy/Reproduction Allowed
NO
NO
NO
NO
API Confidential
Check +5V power
Check Gnd & +5V
and the R,C CKT
Check HBNK & V-
Check R1906 &
R1907
7277e Monitor Service Guide
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