Zenith Z-100 Series, Technical Manual

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Page 5.4
TROUBLESHOOTING
Use the following chart for help in identifying the source of prob-
lems. The chart lists conditions and possible causes for specific
problems. If you cannot resolve the problem, refer to the war-
ranty and service information supplied with your Computer.
If you have electronics service skill, you may wish to service
some problems yourself. In the following chart, if a particular
part is mentioned, check that part and other components that
are associated with it. Remember to locate and correct the
cause when components are damaged, or the problem could
reoccur.
Refer to the "Circuit Board X-Ray Views" for the physical loca-
tion of parts on the circuit boards.
CONDITION
No high voltage.
1.
2.
3.
4.
POSSISLE CAUSE
Q102, Q103, or associated circuitry.
Connector not plugged into vertical deflection board.
No + 12 volts to deflection board.
TX102.
No horizontal sync.
No focus.
No vertical sync.
No vertical deflection.
High voltage present, but no video.
2. Q40 1 , Q402, and associated circuitry.
1 . IC1 0 1 .
2 . Q10 4 .
3. No t i ming pulse at base of Q104 (from main board).
1. Q30 1 , Q302, or Q303.
2. Q3 0 4 , Q306, Q307, or associated circuitry.
3. De f l ection yoke.
1. Q3 0 2 and associated circuitry.
2. No s ync signal from main board.
No video signal from main board.
3. Sri g htness control turned down.
1. TX1 0 2, R148.
2. Hi g h voltage is too low.
1. Yo k e tabs not adjusted properly.
Raster (lighted area) is not centered.