Star Tech Journal

STARHECH JOURNAL/JUNE 1982
8. Too much brightness with retrace
lines; check:
A. Beam limiter transistors.
B. Brightness and/or color blank-
ing control set too high.
9. Increasing brightness causes an
increase in size and poor focus:
A. Weak high voltage rectifier or
regulation (high voltage unit).
10. Small picture and/or poor focus:
A. Low B+ voltage (power supply
trouble).
11. Vertical rolling:
A. Vertical oscillator transistor,
IC, or circuit.
B. No sync from logic board.
12. Horizontal line across center:
A. Vertical output circuit is dead
(see symptom No. 1.A.)
B. Vertical oscillator is not putting
out the right wave form.
13. Picture bends:
A. Horizontal sync needs adjusting.
B. Magnetic or electromagnetic
interference.
14. Flashing picture, visable retrace
lines:
A. Broken neck board.
B. Internal short circuit in the
picture tube (arcing).
15. Unsymmetrical picture or sides
of picture:
A. Defective yoke.
16. No brightness, power supply
operating - no high voltage for
the picture tube; check:
A. Horizontal oscillator.
B. Horizontal amplifier and output
C. Flyback transformer (high
voltage unit).
17. No brightness, high voltage
present; check:
A. Heater voltage to the tube at
the neck board.
B. Screen-grid voltage for the tube.
C. Focus voltage.
D. Grid to cathode picture tube
bias.
9
18. No high voltage; check:
A. For AC input to the "flyback".
B. Horizontal deflection stages.
C. Flyback transformer.
D. Yoke.
E. Power supply.
19. No horizontal and vertical hold;
check:
A. Sync transistors and circuit.
B. Wires and jack from logic board
to the monitor.
20. Wavy picture - (power supply
defect); check:
A. Transistors, diodes, electrolytic
capacitors in the power supply.
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21. Moving bars in picture:
A. Ground connector off between
monitor and logic boards.
B. Defect in the power supply
(see wavy picture symptom).
22. Washed out picture (see picture
not bright enough):
A. Check video signal at the
cathode pins with an oscillo-
scope. If there is about 80
volts peak to peak, the picture
tube has weak emission.
23. Monitor won't turn on:
A. Problem in the power supply:
check fuse, transistors, open
fusible resistor.
B. Shorted horizontal output
transistor.
C. Defective high voltage disabling
circuit.
D. Crack(s) somewhere on main
chassis board.
24. Can't adjust purity or convergence:
A. Use a degausser to demagne-
tize the picture tube carefully
following your degausser's
instructions.
B. Picture tube defective.
C. Metal foreign material is in
picture tube shield.
D. Nearby equipment is electro-
magnetically interfering.
E. The poles of the earth are
pulling off the purity.
F. Poor focus or width of picture.
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