Editing Osborne Vixen Troubleshooting Guide (section)

== Display & Chime Diagnostics ==

The Osborne Vixen has a built-in monochrome CRT. Video faults are common and often easy to localise.

=== CRT & Video Faults ===

{| class="wikitable styled-table"
! Symptom !! Probable Cause !! Remedy
|-
| CRT glows, but no text or border || Video signal missing, logic board not running || Check CPU, ROM, RAM, and video output ICs
|-
| Horizontal line only || Vertical deflection failure || Inspect/replace vertical output IC, check for cold joints
|-
| Vertical line only || Horizontal deflection failure || Check horizontal driver transistor, flyback transformer
|-
| Dim or flickering display || Ageing CRT, weak PSU, bad capacitors || Adjust brightness, recap video board, check PSU
|-
| Garbled or missing characters || Video RAM or character ROM fault || Test/replace video RAM/ROM, reseat socketed chips
|}

=== Diagnostic Steps ===
# Observe CRT at power-on: does it glow, display raster, or show garbage?
# Listen for relay click or faint high-voltage whine (indicates CRT HV present).
# Adjust brightness/contrast—if raster appears, logic board is likely at fault.
# If no glow, test CRT heater voltage and inspect video board for failed parts.