DEC VR315 Service Manual page 19

Table 2–3 (Cont.) Poor Display Quality
Symptom Possible Cause
CRT is worn out.
Display is too bright. Brightness control is
set incorrectly.
Video casting
assembly is faulty.
Deflection module is
faulty.
Vertical lines are not Local magnetic fields
straight. are present.
Deflection module is
faulty.
Faulty CRT/chassis
assembly
Video noise (Display The signal cable is
has intermittent loose or faulty.
flashing or changes
in brightness.)
Video casting
assembly is faulty.
Deflection module is
faulty.
Power supply module
is faulty.
Host system is faulty.
Focus is not sharp. Adjustment is
incorrect.
Deflection module is
faulty.
Troubleshooting 2–7
Suggested Solution
Replace the CRT/chassis
assembly (Section 3.2.6) only
after trying the previous
solutions.
Set the brightness control to
the optimum range.
Replace the video casting
assembly (Section 3.2.5).
Replace the deflection module
(Section 3.2.4).
Remove any electro-
mechanical devices from
the vicinity of the monitor, or
move the monitor.
Replace the deflection module
(Section 3.2.4).
Replace the CRT/chassis
assembly (Section 3.2.6) only
after trying the previous
solutions.
Reseat the connectors or
replace the signal cable.
Replace the video casting
assembly (Section 3.2.5).
Replace the deflection module
(Section 3.2.4).
Replace the power supply
module (Section 3.2.2).
Repair the host system.
Perform the FOCUS
adjustment (Section 4.5).
Replace the deflection module
(Section 3.2.4).