Editing Apple Lisa Troubleshooting (section)

== Video Problems ==

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{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ '''Display Issues'''
|-
! Symptom !! Possible Cause !! Recommended Action
|-
| No display, system runs || CRT failure or analog board issue || Check CRT connections; test analog board
|-
| Horizontal line only || Vertical deflection failure || Check vertical output IC and capacitors on analog board
|-
| Vertical line only || Horizontal deflection failure || Check horizontal output transistor and flyback
|-
| Image shifted horizontally || H-position adjustment needed || Adjust horizontal position potentiometer
|-
| Garbled/checkered display || Memory or video RAM issue || Test with known-good memory cards
|-
| Bright flash/line at shutdown || Normal CRT behavior || CRT discharge is expected at power-off
|-
| Dim or faded display || CRT aging or brightness adjustment || Adjust brightness; CRT may need replacement
|}

=== CRT Adjustments ===
* Horizontal and vertical position/size controls are on the analog board
* Focus adjustment may be on the flyback transformer
* Always discharge CRT before making adjustments