[TechAssist] Re: Best way to clean a head.
- From: gulftech@xxxxxxxx
- To: techassist@xxxxxxxxxxxxx
- Date: Sun, 25 Nov 2001 17:48:00 -0600
Dennis,
Regarding the brain teaser, I came up close to Clint at approx 80 miles.
At 1800 rpm, the drum has 648, 000 rotations in a six-hour period.
With a drum diameter of 2.5 inches, its circumference is 7.853975 inches.
Therefore, a point on that circum. would travel 5,089,375 inches, or
about 80 miles.
You better give the answer, teach!
Ken Smith
Gulf Technical Services
3034 Gulf Breeze Parkway
Gulf Breeze, FL 32561
850-934-8324 (Voice) 850-932-0819 (Fax)
On Sun, 25 Nov 2001 09:47:57 -0600 "OrpheusComputing.com Repair"
<techassist@xxxxxxxxxxxxxxxxxxxx> writes:
>
> For the TAPE, the "actual writing speed" if I remember
> correctly is 19 fps. 3600 seconds in an hour, so 6 hrs has
> 21,600 sec in it. Traveling at 19 fps, that's 410,400' or
> roughly 78 mi. that is "writes". Not sure if that's what you
> mean by "travels". :-)
> -Clint
>
> Happy Thanksgiving &
> God Bless Us All
> Clint Hamilton, Owner
> http://OrpheusComputing.com
> http://ComputerHardware-ConsumerElectronics.com
> sales@xxxxxxxxxxxxxxxxxxxx
> Fax: 209-882-9602
> TechAssist Administration
> http://tech-assist.org
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> (PLEASE include our previous correspondence
> if replying to this email!!)
>
>
> > Larry:
> >
> > I disagree with your statement, "I takes 2 heads to
> complete a full picture".
> > If on head is bad and the other good you will be missing 1
> field of video. If
> > you remember oUR NTSC format consists of 1 frame of video
> is equivalent to two
> > fields. The fields are interleaved together not appended to
> to the end of the
> > first field.
> > Since they are interleaved together one will end up with 1
> line of video and 1
> > line of snow then 1 line of video and 1 line of snow. This
> pattern will
> > continue
> > throughout the entire video field.
> >
> > The reason you get a picture on half of the screen, usually
> the top, is
> > because
> > of head protrusion. The surface of the head must impinge
> into the tape
> > slightly
> > just after the entrance guide. This impingement depth must
> continue for the
> > entire 180 degree swipe of the video head "A" and repeat
> this process for
> > video
> > head "B".
> > The main factor that effects head protrusion are wear.
> Obviously head wear is
> > something that only replacement is the answer. Insufficient
> back tension
> > coupled
> > with head wear is usually responsible for the assessment
> mentioned, "even and
> > inch of video showing on the screen the heads are good" I
> would agree with in
> > part.
> >
> > As the video head travels around at 1800 rpm it creates air
> turbulence, This
> > turbulence does not negatively effect the entrance side of
> the drum assembly
> > where the tape meet the head. In fact the trailing side of
> the video head chip
> > had a lower pressure and will suck the tape in closer to
> the head. But after
> > the
> > head has traveled 60+ millimeters to playback or record of
> the first video
> > field
> > it looses the head to tape contact. One or two primary
> factors can cause this,
> > insufficient back tension and head wear.
> >
> > Any debris on the drum, or the video, or HI-FI heads can
> cause the tape to be
> > pushed away from the head trying to read it. This is why
> the air channels in
> > the
> > drum must be kept free of any debris too. It is just as
> important as the video
> > head chips.
> >
> >
> > I have a brainteaser for the group. How many miles does
> single video head
> > travel
> > in 1 single pass of a 6 hour EP VHS tape?
> >
> > Dennis Viereck
> >
> >
> >
> >
> >
> >
> >
> >
> > Ledstiles@xxxxxxx wrote:
> >
> >> In a message dated 11/24/2001 4:27:32 PM Pacific Standard
> Time,
> >> billmcfarland@xxxxxxxxxxxxxx writes:
> >>
> >> <<
> >>>>> Howdy Wally,
> >>>>> If the heads are bad there won't be any video showing
> on the screen,
> >> if
> >>>> you have even and inch of video showing on the screen
> the heads are
> >> good,
> >>>>
> >> Wally . This above is sooooo wrong. Most bad head problems
> I run across have
> >> the 1/2 good picture display. I takes 2 heads to complete
> a full picture
> >> after all.
> >> Larry
> >> N.C.S.
>
>
>
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