On Sep 23, 2:09 pm, trag <[email protected]> wrote:
> Thank you for all the suggestions, gentlemen. There are some good
> ones here. You guys did a better job than the folks over at Ars
> Technica. :-)
>
> I think that I will try a double sided tape as that appears to be what
> was used before. Picking the correct tape is the difficult part. I
> will look at the thickness of the old tape more carefully when I am at
> home.
The scanner is successfully fixed using 3M double sided tape. The
stuff worked like a charm.
I disassembled the scanner (two screws, Umax 600S) and then the glass
and upper housing. The latter was easy as the two were falling apart
already. First I tried Goo Gone or some similar lemony smelling
stuff to clean off the old adhesive but it did not seem to have any
effect. I switched to 91% isopropyl alcohol with cotton balls and
that did the trick. It took a bit of elbow grease and it helps to
apply the alcohol with a well soaked cotton ball and give it a few
moments to soak into the old adhesive. I used up about a third of a
bag of cotton balls...
The plastic housing had old adhesive on it. The glass had the actual
tape matrix stuck to it. So the thing that fails appears to be the
adhesion between the tape and the plastic.
With some care and effort I was able to peel the tape off of the glass
in nearly full strips. That removed most of the old adhesive, but it
still needed cleaning with alcohol as well. Even after the glass
appeared clean, a newly soaked cotton ball rubbed across the glass
would pick up a yellow stain. So after removing "all" the adhesive,
it's a good idea to make a couple more passes. I finished up by
cleaning the glass with Windex and a soft cotton rag. This scanner
just uses clear glass. Windex would be a bad idea on a scanner whose
glass has a special coating--if such exist.
This is the tape I used:
<http://www.shop3m.com/dt272990789.html>
There are three tapes in this category. They differ in the carrier
(matrix) used and the temperature tolerance. The one I chose has a
polyester carrier and the highest temperature tolerance of the three.
The other carrier choices were tissue and PVC.
After removing the old tape from the glass and getting a good look at
its carrier and thickness, I think that the tape I bought is a nearly
perfect match. I bought a roll of the 25mm and a roll of the 12mm
wide, because one edge of the scanner uses the 12mm and the other
three edges use 25mm. I did not want to try trimming the 25mm to 12mm
by scissors.
The tape peels off the roll with one side covered by a liner and one
adhesive side exposed. After everything was carefully and
thoroughly clean, I started the tape at one end along one edge of the
plastic housing and carefully unrolled and applied it as I went until
I was near the end. It is important to start the tape straight, as
you do not want it veering off into the glass opening, nor away from
the opening. Then I cut the tape with scissors a little longer than
needed. Once the roll was out of the way, I used a single edged razor
blade to trim the end of the tape to just the right length. I
repeated this for the other three edges in the plastic housing. I
then used the safe edge of the blade to rub the tape onto the plastic
and ensure that there were no bubbles in the tape.
After applying the tape, I had the upside down upper housing in front
of me. The four edges around the hole for the glass all had tape
applied, but the tape liner was still in place protecting the sticky
side meant for the glass. I made sure the glass was ready. Then
peeled up the liner from the four pieces of tape. Then I carefully
lowered the glass onto the exposed tape. After the glass was in
place, I ran my hand around the outside of the plastic housing
pressing inward, while running my other hand (in a clean cloth) along
the glass pressing outward, so as to squeeze the glass and plastic
together all along the joint.
After that I reassembled the scanner and it worked like a champ. The
glass displays no tendency to come loose. I guess this tape just has
a twelve year life or thereabouts.
Jeff Walther
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