RetroMacCast

Where great old Macs live again!

I have just taken delivery of a Macintosh Plus and a Macintosh SE. Both were very kindly given to me,
by a university lecturer who has just retired. Both machines where stored away in a back room, not being used
for years. He found them when he was cleaning out his belongings and did not want them to be skipped.

I have chosen the Plus, to be the machine that I will work on to continue my blog about restoring and cleaning.
In part one. I described some of the tools I use and the items I use for cleaning. This time I will inspect the machine
and clean up the case.

The plastic case of the Plus is in good condition, it has no marks, stickers, scuffs or engravings which is unusual
for a machine that has come from the education field as normally they would have marked it with the postcode or
the university name. The case also looks like it has not been subjected to much UV light, as it only has slight
yellowing. Although the case is a little dirty the only real dirt is on and around the power switch.

Opening and cleaning the case
I opened up the case using the Torx 15 screwdriver with the long shaft. Remember on the original Macintosh,
the 512k and the Plus they all have a fifth screw under the PRAM battery cover. Sometime the back case can be
little hard to remove. I normally place the Macintosh face side down, and pull the back case off. The weight of the
components inside help with this. if the case appears to be stuck, try gently pushing the I/O ports or the power
inlet, whilst holding the back case.

With the back case removed, I put the exposed machine out of the way in a safe place, where it will not be
damaged. The CRT contains a vacuum which may implode if damaged, it also contains dangerous substances
like mercury. So it is important that nothing falls onto it when it is exposed.

Now that the back case is separate, it is safer and easier to manoeuvre it around. Using a multi purpose house
hold cleaner and a toothbrush, I gently scrub over the outer case bit by bit. I wipe up the excess liquid with a lint
free cloth, buffing it up as I go along. The toothbrush is a ideal tool for this, as it gets into the vents and inside the
handle without a problem. A non scratch scourer can also be used on large areas or more stubborn dirt.

The cleaned case

Normally I just wipe inside the case with a lint free cloth and brush the dust from the hard to reach places with a
paint brush, but I had an Idea and decided to experiment. The inside of the case is coated with a metal oxide to
help stop interference, over time the metal gets tarnished and becomes dull. So I decided to polish it with some
metal polish. The polish I used is called Peek. I used a lint free wipe to apply the polish and another to buff it up.
The results were excellent as you can see from the pictures below.

Before


After

The front part of the case will have the same treatment, but I will have to remove the other components attached to
it first. That we will start to cover in the next part. Let me know if you have any comments or questions.

Views: 181

Comment by Lars (WhyOSX) on September 15, 2009 at 4:04am
If a CRT implodes when it is running, Osmiumtetroxide evades - highly toxic, causes cancer,
especially if inhaled, lung cancer.
The screen is covered with Bariumsulfate on the inside - not dangerous because it is hardly solvable with water.
Comment by Damian Ward on September 15, 2009 at 2:02pm
Thanks Lars, for your comment and additional information which underlines the importance of caution when working with or around CRT's. Perhaps I should also mention the high voltage that they also can store for days.
I will try my best to cover discharging a CRT in my next blog.
Comment by Lars (WhyOSX) on September 15, 2009 at 6:17pm
But what I forgot to mention is the risk of high voltage remaining in the capacitors.
You're an expert, but not everyone else.
Keep the machines surely (safely) grounded and wait a while
(depending of the power supply in your country !).
Opening a not running CRT or TV screen on the back side can be done with a small (100 grams) hammer, if the item is covered (carpet or something in that style). It is not too dangerous then.
And BTW they should go to special recycling.
Comment by macmedic on October 2, 2009 at 7:52am
As someone that's had a faulty iMac analogue board discharge 10Kv of stored voltage into their hand, I think Lars makes a valid point kiddies, and I am a professional - We all make mistakes. I always suggest no one works on any CRT or Analogue assembly without someone else around in case of emergency.
Comment by macmedic on October 2, 2009 at 7:52am
P.S I love how the EMI paint came up.. Looks fantastic
Comment by TheNixer on January 2, 2010 at 6:14pm
That Peek cleaner did an amazing job on the inside of that Plus! You've definitely inspired me to do that to the Plus I have apart at the moment.

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