nusual Screens

This chapter covers unusual screen happenings. All user level repairs require an analog board change unless otherwise indicated.  See the chapter "compact Macs"  for changing the analog board.

 
Wavy lines on the screen

 
The display is short
(try a  vertical adjustment. See:  "Adjusting screen 
size")

 The display is narrow
(try a  horizontal adjustment. See:  "Adjusting screen
 size")

 
Screen jittering or shimmy
Replace the analog board see if the ground on a
 Mac Plus is loose.  (Green ground wire on the
 back edge of the analog board).

 
The screen jitters during drive action or when 
windows are open.

 
Letters on the edge are stretched compared to the 
center.(The wider areas could be just on one
 side too.)

 
Bright vertical line.

 
Bright horizontal line

Lines or Checkerboard  Compact Macs: the reset
switch on the side of the
computer is depressed.
Remove or reseat it.

 
Display out of focus (see Compact Macs)
 or a new logic board is needed

Display isn't rectangular or is off to the side or is tilted.
Try height and width adjustments
(see Compact Macs) or
video neck yoke is out of adjustment.
You should see a technician about 
this problem

 Vertical bars and the happy Mac stays
If you recently inserted RAM chips (simms)
Then they are in the wrong place on the logic
board of an SE or SE30.

Checkerboard pattern One of two things:
1. Reseat the ROM simm on the logic board
2. The ROM simm is put in backward or defective
Replace logic board or inquire about repair.