Dim Video; Other Video Problems; Fails Self-Test Of Diagnostic Tests - Wyse WY-60 Maintenance Manual

Figure 3-1 Troubleshooting Flowchart, page 5 of 7
Dim Video
1.
2 .
3.
Check user
brightness control
Adjust brightness
Check brightness
circuitry
Adjust the brightness slideswitch.
Perform the brightness alignment
found in "Brightness", Chapter
4.
Check VR202, VR203, VR204, D203,
and 0205.
Pin 1 of the CRT (att"lched to the
green wire) should vary between +12
and -100VOC when the brightness
control slideswitch moves from its
highest to its lowest points.
Check all connected circuitry.
Check video output pins on U20.
Other Video Problems
1 •
2.
3 .
A vertical line
of video
A horizontal line
of video
Raster, no video
Check the vertical yoke and the
vertical deflection circuit.
Chec k the yoke.
Check the video amplifier, U20, all
open video lines, and the CRT socket.
Fails Self-Test or Diagnostic Test
1 •
2.
Check setup
Check loopback
connectors
Make sure you correctly selected
the diagnostic test.
They may be missing, on the wrong
ports or faul ty. Check Append ix C
to make sure all connections are
correct.
If a letter has appeared on the screen, before running the
self-test, or you have run self-test, and one or more letters or
numbers appear on the screen, check the error codes below and
their corresponding recommended actions. All components referred
to are found on the logic PCB unless otherwise stated.
3-10