Q770 Technical Service Manual
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Trouble Shooting
1. Introduction
This trouble shooting guide is arranged by fault conditions. Following each fault condition is a check
for a signal on condition to be answered YES or NO.
For NO answer proceed to the right and continue until the fault is located.
For a YES answer continue in the left column to the next numbered check.
Again followed this procedure until the fault is located.
2. Trouble shooting procedure
When Troubleshooting this monitor, some precaution should be observed.
Use a high quality isolation tranformer is capable of providing 3 Amps or more.
Never connect primary ground and secondary ground together including use with an isolation
transformer.
Measure high voltage with respect to chassing ground only, and with a high impedance prove of 1000
mega-ohm or higher and rated for 30KV DC or higher.
Measure QH09 collector pulse with a high quality 100:1 probe rated for 1500 volts or higher.
3. Troubleshooting procedure
Symptom
a) Image is
scrolling.
b) Image is
unstable.
Check(YES)
1) Check for Vsync at pin 41 of ICM01
2) Check for positive going Vsync at
pin 2 of ICH01.
3) Will V-oscillator is locked with input
signal?
(pin 22 of ICH01)
4) Check V-ramp at pin 23 of ICH01.
5) Check V-out at pin 5 of ICV01.
1) Check for Hsync at pin 40 of ICM01
2) Check for positive going Hsync at
pin 1 of ICH01.
3) Will H-oscillator is locked
with input signal?
(pin 6 of ICH01)
4) Check H-out at pin 26 of ICH01
5) Check for flyback pulse at pin 12 of
ICH01.
Action(NO)
Check 15 pin D-sub connector, cable,
ZDM02.
Check ICM01, ICH01
Check CH01, CH02
Replace ICH01.
Check B+ at pin 2,4 of ICV01.
Check 15 pin D-sub connector, cable,
ZDM01.
Check ICM01 , ICH01
Check CH06, RH06
Replace ICH01
Check RH10
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