Re: [ARSCLIST] Little azimuth trick

[eugene audio <eugeneaudio@xxxxxxxxx>]

Hi Folks,
  It's very nice to read many of you are totally
familiar with head alignments.
  As a very new list member, I don't know your
experience. I would like to contribute what I
can, when I can, so my apologies if I state what
is obvious to everyone. There have been some very
interesting
and informative threads I've followed over the last 2
months. So I'd like to return whatever I can as far
as my experience goes, which is primarily from the
audio electronics technician field.
  For my curiousity, do "you" normally address
the tilt and tangent alignments when doing head
alignments ? I've found this is an area where
misadjustments can be very common and lead to
unevenly worn heads. I use a variation on the old
grease pencil trick for this.


Respectfully,
Chris
@eugene-audio

--- Mike Richter <mrichter@xxxxxxx> wrote:

> George Brock-Nannestad wrote:
> > From: Patent Tactics, George Brock-Nannestad
> >
> > Hello,
> >
> > Chris @Eugene wrote
> >
> >
> >>Hi,
> >>   The normal correct procedure, according to
> service
> >>manuals, is to adjust for maximum signal strength,
> >>before "fine-tuning" with a Lissajous pattern for
> >>phase relationship. It is possible to get the
> >>correct Lissajous pattern at less than maximum
> >>signal strength azimuth adjustment.
> >>   Usually what I do is watch the signal strength
> >>on an audio voltmeter or the o'scilloscope. Adjust
> >>for maximum amplitude, then you can "tweak" it
> >>very, very slightly for the proper Lissajous
> >>pattern.
> >>   Hope this helps.
> >>
> >>Chris
> >>@eugene-audio
> >
> >
> > ----- this is what we all do. However, Richard
> took the signals from the
> > "edge" tracks (i.e. those almost ½ inch apart),
> realizing that the 1 kHz
> > signals (a _low_ frequency) were in phase in all
> channels, and generated the
> > Lissajous from these. This is a good (and novel)
> way to obtain precision. The
> > need for obtaining a maximum amplitude reading
> does not arise at this low
> > frequency - you cannot tilt the head so much that
> you get an erroneous
> > "lower" maximum at this frequency, unless it is a
> monitoring tape at very,
> > very low speed.
> >
> > Thank you, Richard, for this neat trick!
> >
> > Kind regards,
> >
> >
> > George
>
> Well, you *can* get an amplitude difference, but it
> is a cosine effect
> of the misalignment. The Lissajous figure shows
> phase difference, a sine
> effect. For any moderate alignment error, the cosine
> effect is likely to
> be swamped by even slight amplitude variation where
> the phase error will
> be reliable and easily read.
>
> Mike
> --
> mrichter@xxxxxxx
> http://www.mrichter.com/
>