[TechAssist] Re: Best way to clean a head.
- From: "Jeff Dougherty" <jeff@xxxxxxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Sun, 25 Nov 2001 12:49:01 -0500
As Al would say ROFLMAO!
Jeff
mailto:Jeff@xxxxxxxxxxxxxxxxxx www.9-11-2001tragedy.com
FAX 1-413-280-0677
Intrepid Video & Electronics
Harrisburg, PA 17111
717-909-8844
www.intrepid-video.com www.tech-repair.net www.thetoolcaddy.com
----- Original Message -----
From: "Edward Gaidies" <teltek@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Sunday, November 25, 2001 10:18 AM
Subject: [TechAssist] Re: Best way to clean a head.
>
> Really shouldn't travel any miles, at least, if it's screwed down
securely.
> Sorry Dennis....couldn't resist. ;-)
>
> -Ed-
>
>
> >
> > 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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