Chart C-1 - CRT Problem

Chart C-1:

CIRCUIT DESCRIPTION:

Following the Self-Diagnostic System Check first verifies the integrity of the circuits to the CRTC. Because the CRTC, which drives the CRT, is known to be in communication with the rest of the system, the problem must be the CRT, CRTC, or the circuitry between the two. At this point, the problem is with the display of the picture on the CRT, or its ability to interpret switch positions touched on the screen. CHART C-1 breaks the problem down into symptoms so the cause of the problem can be identified quickly.

TEST DESCRIPTION:

1. Following CHART C-3 will isolate problems that can cause the BEEPER to not work or sound all the time, or the switches on the face of the screen, including the border switches, to not be recognized. (No switch can be recognized).

2. Following CHART C-4 will isolate problems that can cause some but not all of the switches to work, (at least one works).

3. Following CHART C-5 will isolate problems that can cause the CRT's picture to roll.

4. If the CRT has a border switch LED problem, the CRT must be replaced, unless all LEDs do not work in which case the BEEPER and/or switches will also not work if the cause is a circuit problem. It is unlikely that all of the LEDs would burn out at once.

5. If the problem is with the CRT's backlighting or dimming control, diagnosis will be covered in CHASSIS ELECTRICAL DIAGRAMS. This will not prevent entry into the on-board diagnostics.