4.1 No display; Wobbly display; Single vertical line down the middle If the Mac seems to function well (e.g., you hear the boot bong, disk accesses occur the
way they should, etc.), but has certain display problems, this section is for you. Many dis-
play-related problems are due to the notoriously unreliable solder joints on the yoke con-
nector J1. These should always be resoldered as a matter of course because a visual
inspection does not always reveal problems such as hairline cracks. Flakiness here results
in symptoms that include an intermittent raster, wobbly/shaky/jittery raster, no raster,
uncorrectably narrow raster, or a single vertical line down the center of the CRT. Quite
commonly, slapping the side of the Mac can make these symptoms come and go if the
connector is indeed the problem. Without question, this is the most common fault with the
analog board. It’s sad that so many old Macs are tossed in the trash because of this prob-
lem, because it’s trivial to fix, most of the time.
To repair, simply freshen up the yoke’s four solder connections to the analog board, while
leaving the connector halves mated, or else the heat will melt the connector plastic and distort its shape. You’ll never be able to reconnect the two halves if you fail to fol-
low this advice.
And don’t be lazy and simply reheat the old solder that’s there -- use new solder. Use
enough heat/duration to get the solder to flow well, leaving a shiny, smooth surface upon
cooling. After it’s cooled down, disconnect the two halves and inspect the four mating
pairs of contacts for signs of oxidation or burning. Repair or replace as necessary. If you
can’t locate a replacement (or don’t want to wait for one), you can always simply hard-
wire the connections (e.g., desolder J1 from the analog board, remove its mate from the
yoke cable assembly, and just solder the four yoke wires directly to the analog board). The
drawback is that if you need to remove the analog board later for some reason, you’ll have
to undo the connections.
