Subj : FIXES731
To   : All
From : Joe Paulson
Date : Mon Aug 01 2005 12:11 am

 
I have a hobby of tring to fix audio and VCR tapes and
CDs and DVDs for the Claymont ,Delaware library as follows:

I  measured the tape in 60 min.audio cassette tape- 30 min.each 
side and got 260 feet.

Ran into a bad DVD-stops near end-some small scratches-
couldn't see anything even after cleaning wih pure Isopropyl 
alcohol or a mixture of 50% I-pr and 50% ethyl acetate
(solvent of last resort).Pure ethyl acestate makes the 
polycarbonate disk transluscent.I noticed a lot of microscopic 
blisters on the edge-only way to see it was when it was wet 
with alcohol and I could tilt the disk so the light reflected 
off it.It could be CD rot, maybe overheated or stored at 
high humidity.The disk was useless.

Experimented with some free AOL disks by deliberately making
scratches and see if they still worked.If the scratch was 
radial from the center to the edge,the Cd skipped but still
played.If the scratch was parallel to an edge,i got a message 
that there was no disk.AOL kept trying to Install and finally
I got a DOS program "Disk Detective" that can measure every
byte on the disk.It was VERY SLOW on my 486 but it worked.
This goes along with the idea that on small scratches,
the reader takes the data on each side of a scratch and 
calculates a phantom reading.

Had some bad VCR tapes with a ight fog of dots fading in and 
out.Now I'm suspecting magnetic damage from some Library checkout
system.I've had some audio tapes with magnetic damage where the
volume goes up and down .

Had some library DVD disks with small cracks at the center,I put 
a Scotch tape ring around the center hole to keep the cracks 
from spreading, I got some backing sheets from self-stick
labels ,placed a piece of Photo Scotch tape on it,drew a 1 inch OD
circle with a pencil,then cut out the circle leaving a part of 
the backing sheet open so I could get get the tape ring off.
Then placed the tape circle over the center hole,and used a 
double-edge razor blade to cut out the center opening.
Didn't have a sharp carving tool with a handle.
Then run my finger inside the hole to smooth out the center hole.
I put notes on the DVD case so I'll find out how soon it lasts
if the disk comes back for repairs. 
The library has circular labels but the holes don't exactly
cover the edge of the center hole.The cracks start inside the hole.

While working with backup sheets from adhesive labels,I found 
that they are perfect for fixing the ends of a roll of tape,
especially duct tape.I fold the backing sheet in half with the 
nonstick side out and tuck it under the end of the tape.
I used the backup strip from a roll of stamps under the end
of a 1/4 " thick roll of tape.

I ran out of AA akkali batteries so I bought 8 2300 mAh 
PowerEx NiMh batteries and a charger (only AA ),from Thomas 
Distributing,(batterysupply.com) for $41 plus $7 shipping.
They last and last.They recommend recharging every 30 days
and I guess this goes along with the self-discharge rate of 
one % per day.Howver,I keep them refrigerated for results of the 
following experiment.I should be able to cycle them 300-400 times. 

As described in a previous FIXESxxx note,I open a defective 
laptop battery pack and got 6 good NiMh long batteries,
(Type L-AA ?) 67 mm hi,15 mm OD.After using them for a while,
I decided to test how long they would hold their charge in the
refrigerator.After storing fully charged for 70 days( 2 months
and 10 days),I tested them (warm) and the voltage only
dropped from 1.39 to 1.34 volts when tested with a radio load.
Now,I realize that the volts doesn't measure mAh but it sure
looks like refrigeration slows the discharge.
I now keep ALL my rechargeables in the refrigerator,including
the battery packs for portable drills.


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