MicroVAX equipment

From: Chuck McManis <cmcmanis_at_mcmanis.com>
Date: Thu Jul 19 19:22:35 2001

At 12:33 AM 7/20/01 +0100, Tony wrote:
>A winchester has am HDA (Head Disk Assembly) which can only be taken
>apart and repaired in a cleanroom. I don't have a cleanroom at home, so I
>can't repair HDAs.

Actually you can make a clean room fairly easily with a 10 gallon aquarium
tank and a blower.

First, find a tank that has polycarbonate (aka Lexan) sides (generally they
are the cheap ones here.) Remove one side, cut two 6" diameter holes in the
side. Now glue a pair of latex tubes (6" O.D.) on to the sides by
overlapping about an inch, stretch the latex, and epoxy to the sides. Now
tighten the end of the tubes by overlapping the edges to make their
diameter approximately 1/4" less than that of your wrists.

Build a new top for the tank using another piece of Polycarbonate (note you
can do everything from the top but it gets crowded. Install a squirrel cage
blower and a HEPA 0.1 micron filter. The filter is going to slow your
airflow considerably so you want your blower to give you a net positive
pressure _after_ it blows through the filter. Now create another hole in
the top and cover it with three or four heater type filters. If you get the
kind they sell for folks allergic to pollen they should be great. This is
your "exit" smoke stack. It isn't filtering so much as trapping the
particles that you are purging from the work space.

Now put your disk and tools in the tank, put on the top, run the blower to
"purge" the air (leave your hands out of the tubes for a minute or so),
wash your hands really well, stick them through the tubes until your hands
pop out the end and the tube is sealed on your wrist. Wait a bit more to
purge any particulates you've introduced. Now fix the drive :-)

I've seen heads replaced this way (in a hand isolation tank) but typically
unless you have a head assembly handy you won't be able to do much in there.

I can't remember where I saw the plans to build something like this but I
believe it was the Amateur Scientist column. They also had you put on latex
gloves but since you aren't worried about getting infected or anything from
the drive I don't think you would need them.

The trick here is that you don't need a clean "room" you only need a clean
"workbench" area to work.

--Chuck
Received on Thu Jul 19 2001 - 19:22:35 BST