ImageQuest Q770 - Page 15

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Symptom
c) Screen is black
but high voltage
is present.
d) Screen is black
with no high
voltage.
e) No power
Check(YES)
1) Check for G2, pin4 of CRT.
Around 500 volts?
2) Check for heater voltage at pin 6 of
CRT. (about 6.3V)
3) Can screen be lit with brightness
control at MAX?
4) Check for video at pin 5, 6, 7 of
ICC01
5) Check for positive pulse for clamp at
pin 23 of ICC01.
6) Check if contrast controls video level
at pin 18,19,20 of ICC01.
7) Check for video at pin 1, 2, 3 of
ICC03.
8) Check if R, G, B cut-off control the
video DC level at pin 6, 8, 11 of CRT.
9) Check CRT.
1) Is the LED01 lighting in Green color.
2) Check for 14V at collector of QP07.
3) Check output pulse at pin 26, 28 of
ICH01.
4) Check Hor-Drive pulse at Base of
QH09.
5) Check B+ at pin 2 of TH04.
1) Check ICP01 pin 4, 7
2) Check switch pulse at Drain of QP04.
3) Check voltage for, 55V at Cathode of
Dp11 and for 7V at Cathode of DP13
and for 14V at cathode of DP15
Check QP01, QP02, DP16, DP07
Check pin 6, 3 of ICP01, RP11
Recheck above Item(d).
Action(NO)
Check DH28, RH96, RH92, CH53, CRT
socket. G2 Wire
Check DP13, RP24, RP25, QP05
CRT socket. RC32, CNC01
Check DH21, DH25, QH18, QH19.
DH26 RH99. CRT socket.
Check 15 pin D-sub connector, cable,
DC4,5,6 Check
Check ICM01, RC13, CNC01
Check ICM01, ICC01, 5V
DC (Pin9)of
ICC01
Check ICC03, 75V
DC (pin 4)
12V
DC(pin 8)
Check ICC04
Check H.V Sync at pin40, 41 of ICM01.
Check pin 8,9 of ICM01.
Check ICM01, ICM02,ICC03
Check QP07, QP08.
Check pin 10 of ICM01.
Check for Vcc at pin 29 of ICH01.
Check oscilation pulse at pin 6 of
ICH01.
Check X-Ray voltage below 8.0V at
pin 25 of ICH01.
Check RH11, RH12, RH13
Check QH08, TH01.
Check DH07, LH01, QH07, QH05
QH06, RH41, RH42, RH39, RH16,
ICH01