OT: Cleaning video head on my Betamax VCR

[Gene Heskett]

On Sunday 10 August 2008, Steve Underwood wrote:
>Gene Heskett wrote:
>> On Sunday 10 August 2008, Mogens Kjaer wrote:
>>> Thompson Freeman wrote:
>>> ...
>>>
>>>> As solvents, it is my impression that isopropyl alcohol and ethanol are
>>>> very similar. As such, I'm curious if the video engineers have tried
>>>> it.
>>>
>>> In my spare time (!) I'm involved in a society for restoration
>>> of old, Danish computers.
>>>
>>> We have a ½" 9-track tape drive (with SCSI interface, connected to
>>> a Fedora box, bringing it a bit on-topic again).
>>>
>>> Some times when reading old magtapes, the heads become very dirty.
>>
>> Where are the tape being stored?  Tape, in higher humidities and temps,
>> becomes very abrasive, recommended storage is for relative humidity to be
>> under 25% and temps below 50F.  I once was the ACE at a tv station where
>> the tapes were all stored in between uses in a walkin cooler held at about
>> 45F. The air conditioner was set for coils at about 34F so they would
>> wring as much moisture out of the air as possible without freezing up the
>> evaporator coils.  We were getting 5000 hours out of a 1000 hour rated
>> u-matic heads way back then.
>
>There is a myth that tape suppliers actually have the slightest clue how
>there products will behave over time. In the 1980s we stored a room full
>of 1" wide Ampex tapes for about 3 years, until we were ready to do some
>further analysis of the flight data they contained. The room was run at
>the temperature and humidity recommended by Ampex, and the logs showed
>this was correctly maintained throughout the 3 years. When we tried
>using the tapes, the binding agent for the magnetic material had
>degraded and stuck the layers of tape very solidly together. We could
>unscrew the side plates of the reels, and cut through the cake of tape
>with a hacksaw. The layers were so solidly bonded that the tape remained
>a solid lump after this treatment, and could be beaten with a hammer for
>a while before starting to break up. If we simply tried unrolling the
>tape from a spool, we ended up with a translucent plastic film, and a
>lot of flaky brown stuff.

I had something similar happen back in the 70's to a 2" quadruplex tape that 
we got in on the 'bicycle' where a tape went from station to station on a 
tight shipping schedule.  Quite well stuck together.  I slowly unrolled it, 
washed the spilled coca-cola off it with water, and had a hair drier rigged 
to dry it again on each side as it was slowly spooled to another reel, then 
rewound it again with the hair driers still running.  I got it to run on our 
old TR-22 that Clint Free had high banded, only one day late, then had to 
ship it overnight to the next station on the bicycle route.  The syndication 
agency threatened to charge us 5 grand for destroying their tape when I 
called to complain that somebody in front of me had spilled a coke on it.  
That was for the "Flintstones" IIRC, and that's one syndication agency we 
never did business with again. At least on my watch.

Old broadcast engineering war stories..  Stick around long enough and you 
*will* see it all.

>Recommended storage conditions are only quoted to create the illusion
>that the tape maker has a clue what they are doing. :-)
>
This humidity/temp/abrasiveness relationship is a _very_ well known fact, 
verifiable by maintenance logs everywhere.

>Regards,
>Steve



-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
You're dead, Jim.
		-- McCoy, "The Tholian Web", stardate unknown