CRT Testing

Testing of the CRT can only be accomplished with the use of the CRT Tester (J-34914). This tester is used to isolate faults between the CRT, CRTC and wiring. Substituting the tester in place of the CRTC verifies the integrity of the picture tube and switch circuitry that make up the CRT. By connecting the tester directly to the CRT, it can be checked out as a unit.

After the CRT has been checked out, connecting the tester to the vehicle harness determines if the fault is in the wiring or the CRTC. The tester runs through an automatic test, and then allows individual switch tests.

Pressing the "RESET" button on the tester initiates the automatic test sequence. After the CRT has warmed up, a test pattern is displayed which outlines the 25 key pads on the screen. If this pattern is not displayed, replace the CRT.

When the automatic test sequence is complete, the tester is ready for individual switch tests. This test indicates whether there is a problem with one of the CRT's hard or soft keys. To test these switches press the desired switch key pad to be tested. If the CRT "Beeps", the switch is okay. If the CRT does not "Beep" the switch is faulty.

If the CRT checks out okay, check the wiring by connecting the tester to the CRT and CRTC wiring harness. Now, repeat the CRT, and switch tests. This will determine if the CRTC is faulty, or there is a wiring problem.