🚀 go-pugleaf

I've fixed a Mac that had this same problem.  The basic problem is that
the components, wires and connectors in the horizontal deflection circuit
are a bit on the weak side.  This circuit has to carry several amps of current,
and some of the components break down under the strain.

The one I saw failed in the yoke connector.  This is a white plastic connector
that connects the deflection yoke (around the neck of the CRT) to the
top area of the analog board.  Unplug this connector and inspect both halves
closely.  Is it deformed, brown or yellow colored in spots?  Are the wires
ok, or does the insulation look slightly melted near the connector?
Do the flimsly metal connector pins look burnt or heavily tarnished?
Is the connector very warm or even HOT to the touch?  These are signs
that the connector has been overheating.  This causes the connector
pins to tarnish even faster, leading to a poorer electrical connection,
leading to more heat, ... and eventual failure.

Also look at the connector half that is on the analog board.  Excess heat
on this half can cause the solder to remelt and form a bubble over the
connector pin. The connection *looks* perfect from the outside. It fooled
me for a few minutes.  But if you check for continuity with an ohmmeter,
you may find *no* continuity through this perfect looking solder joint.

There are varying levels of solution to this problem:

(1)  Have the analog board replaced by a dealer.  This will "fix" the problem,
but cost you many $$$. I don't know for sure, but I assume that newer
analog boards have sturdier connectors. Apple is surely smart enough to
have discovered and fixed this problem themselves.

(2) If you are handy, you can replace the connector yourself.  Try using
a sturdier connector.  Most auto shops sell very hardy "trailer hitch"
connectors for under $4.  

----

Other things that can go wrong in this area include:

Other solder joints in this circuit can go *bubble up*.  Trace the printed
circuit lines from the connector and try reheating the solder joints.

A capacitor in this circuit can overheat from the strain and fail.  These
will often discolor as a clue.  Replace these with a sturdier array, say
2 capacitors of 1/2 the value each in parallel.

The flyback xformer may fail, especially in very old Macs. These are
identifiable by a bad smell, a cracked case.  If you are
*very* handy at soldering, you can replace this too.  Replacements
are available from MCM Electronics (513) 434-6959 for $33 each.

These weaknesses in the Mac are annoying, but at least their remedy is often
inexpensive.

--- Important Notes:
Don't try any of these steps unless you know all the proper safety
precautions.  You can damage yourself and your Mac if you don't know
how to protect each other.  You *must* know how to safely
discharge high voltage capacitors and CRT's.

You *must* have a static-free environment, and a GROUNDED soldering iron.
A $6 ungrounded iron from RS can easily and instantly blow your analog
or Mac logic board.  I destroyed a $500 car stereo this way.