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Connect the Scandoubler SVGA port to the TFT for the following... As a fall back, connect the Amiga to a TV
Reset the Amiga, hold down both mouse buttons for up to 30 secs until an Early Startup Menu appears - select boot with no startup-sequence
at the command prompt 1> type:
rename sys:prefs/env-archive/screenmode.prefs sys:prefs/env-archive/screenmode.old
Then reset the Amiga and go into Workbench. Goto prefs drawer and run Screenmode. Select the previous working graphics card screen then test on the TFT to see if working. If OK save the settings.