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On Mon, 13 Apr 2009 06:02:03 +1000, Franc Zabkar
<> wrote:

>On Sun, 12 Apr 2009 10:46:33 -0700, Archimedes' Lever
><> put finger to keyboard and composed:
>
>>On Sun, 12 Apr 2009 14:45:07 +1000, Franc Zabkar
>><> wrote:
>>
>>>
>>>I would think that the track pitch is irrelevant.
>>
>>
>> It makes for a doubling of capacity. You have no clue.
>>
>> Look at a CD with a cheap microscope, then try a DVD.
>>
>> There are thousands more tracks on the DVD.
>>
>> More is more. Simple math.
>
>The track pitch is completely irrelevant when considering the
>eccentricity of a disc. If a disc is clamped 1mm off-centre, say,

You cannot clamp up 1000 discs and have them be off by more than one
tenth of one mm, so you will NEVER see 1mm.

The reference to track pitch was about density differences between
formats. Try to keep up.

I wrote:

"The spectrum that DVDs and newer BD discs are at allow for, and so are
used, a much finer pit size and track pitch than CD were at. A LOT
more."

Note that I was not talking about ****ing eccentricities at all.

It would seem that you have many though.

> then
>the tracking coil or voice coil positioner will wobble 1mm from
>side-to-side. It doesn't matter whether the tracks are 0.1mm wide or 1
>Angstrom.

You are the only dope jacking off at the mouth about wobble right now.

I have seen laser discs that cause head transitions of 3/8" at the
outer edge of a wobbly disc. That is the main reason that 5.25" form
factor was chosen. There is nearly no wobble on a stamping of that size,
and the mass is far less as well. Those early players had huge ceramic
magnets with the primary lens being manipulated inside by the "Lens
Positioning Coils". No "voices" anywhere to be found here.

There is no "tracking coil". The lineal position of the lens across
the face of the disc's read surface is nearly always a dual rail gantry
system driven by a worm gear. There are no friggin' coils. The vertical
or FOCAL position of the lens is done by the Lens Positioning Coil
Assembly.

On Sun, 12 Apr 2009 13:07:29 -0700, "The Mighty T.B."
<> wrote:

>"Franc Zabkar" wrote:
>
>>>>I would think that the track pitch is irrelevant.
>>>
>>>
>>> It makes for a doubling of capacity. You have no clue.
>>>
>>> Look at a CD with a cheap microscope, then try a DVD.
>>>
>>> There are thousands more tracks on the DVD.
>>>
>>> More is more. Simple math.
>>
>> The track pitch is completely irrelevant when considering the
>> eccentricity of a disc. If a disc is clamped 1mm off-centre, say, then
>> the tracking coil or voice coil positioner will wobble 1mm from
>> side-to-side. It doesn't matter whether the tracks are 0.1mm wide or 1
>> Angstrom.
>
>Archie's head just exploded. Again.
>
>T.B.

If you could even follow a dialog, you would see where he made the
mistake, and my original reference had nothing to do with eccentricity
and track pitch. My reference to track pitch related strictly to density,
but a total retard like you probably couldn't follow that either.

On Sun, 12 Apr 2009 13:35:24 -0700, Archimedes' Lever
<> put finger to keyboard and composed:

>On Mon, 13 Apr 2009 06:02:03 +1000, Franc Zabkar
><> wrote:
>
>>On Sun, 12 Apr 2009 10:45:07 -0700, Archimedes' Lever
>><> put finger to keyboard and composed:
>>
>>>On Sun, 12 Apr 2009 14:45:07 +1000, Franc Zabkar
>>><> wrote:
>>>
>>>>
>>>>I have a Philips CD204 which has a "radial motor". This positioner
>>>>consists of two coils rotating around a stationery permanent magnet.
>>>
>>>
>>> But they are NOT now, nor have they ever been "voice coils".
>>>
>>> Positioning coils would be as close as you could get to using the term.
>>
>>It's a radial motor voice coil positioner.
>>
>>The earliest hard drives used a "linear motor voice coil positioner".
>
> WRONG!
>
> Despite the design having a resemblance to the transducer of an audio
>output driver, it is 100% wrong to call them a voice coil.
>
> I HAVE a couple of the hard drives you refer to and the name is LINEAR
>MOTOR, not "voice coil positioner".

During the 1980s I serviced Control Data disc drives to component
level. This meant cleaning the debris from between the voice coil and
stationery magnet of BK7 series hard drives after a head crash. This
involved total disassembly of the affected area. I still have the
service manuals. They refer to the part as a voice coil. Its diameter
was the size of a CD.

Here is what other HD manufacturers have to say on the subject:

http://support.seagate.com/support/g...oil_motor.html

================================================== ==================
Voice Coil Motor

An electromagnetic positioning motor in the rigid disc drive similar
to that used in audio speakers. A wire coil is placed in a stationary
magnetic field. When a current is passed through the coil, the
resultant flux causes the coil to move. In a disc drive, the carriage
assembly is attached to the voice coil motor. Either a straight line
(linear) or circular (rotary) design may be employed to position the
heads on the disc's surface.
================================================== ==================

http://www.fel.fujitsu.com/home/glossary.asp?L=en&T=r

================================================== ==================
Rotary Voice Coil Actuator

In principle, the rotary voice coil actuator consists of a movable
wire coil in a stationary magnetic field (similar to the principle of
a loudspeaker). When there is current flowing through the coil, the
resulting magnetic field interacting with the permanent magnet causes
a movement which again acts on the positioning arm. This movement may
be varied infinitely (linear) with the current strength.
================================================== ==================

http://stason.org/TULARC/pc/hard-dri...-SCSI1-SE.html

================================================== ==================
Low cost and high performance are achieved through the use of a
rotary voice coil actuator and a closed loop servo system using a
dedicated servo surface. The innovative MAXTOR rotary voice coil
actuator provides performance usually achieved only with larger,
higher powered linear actuators.
================================================== ==================

http://www.wdc.com/en/company/glossary.asp

================================================== ==================
voice coil

An actuator motor. The force of a magnetic rotary voice coil produces
a movement of the head that is proportionate to the force exerted by
the coil.
================================================== ==================

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

On Sun, 12 Apr 2009 13:57:21 -0700, Archimedes' Lever
<> put finger to keyboard and composed:

> There is no "tracking coil". The lineal position of the lens across
>the face of the disc's read surface is nearly always a dual rail gantry
>system driven by a worm gear. There are no friggin' coils. The vertical
>or FOCAL position of the lens is done by the Lens Positioning Coil
>Assembly.

In a compact disc player, the lens tracks the surface of the disc by
means of two coils, a focus coil for up-down movement, and a tracking
coil to side-to-side movement. Coarse positioning is via a worm gear.

See http://www.repairfaq.org/REPAIR/F_cdfaqa.html

================================================== ====================
First, identify the cable leading to the focus and tracking voice coil
mechanism. This is usually a 4 conductor cable separate from the data
and laser cable (at least at the pickup end). Disconnect it from the
mainboard before testing. Using a DMM or VOM, you should be able to
locate a pair of coils with very low resistance - a few ohms. One of
these is focus coil and the other is the tracking coil.
================================================== ====================

Note that if you have a CD player with a rotary positioner, there may
be no separate tracking coil as coarse and fine tracking may be
combined.
================================================== ====================

Here is a reference diagram for a Cheertek DVD chipset:
http://www.users.on.net/~fzabkar/DVD...65-AM5868S.pdf

Notice the connector pinouts for the Hitachi 1200W optical pickup at
the top LHS of page 3. You will see Track+, Track-, Focus-, and
Focus+.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

On Sun, 12 Apr 2009 14:45:07 +1000, Franc Zabkar
<> put finger to keyboard and composed:

>The principal is similar to what you see in a hard disc drive, but the
>coil orientation differs. To me it looks like a radial voice coil.
>There is no tracking coil within the laser assembly as there is in
>stepper motor CD players.

Correction, the motor is not a stepper. It appears to move in this
fashion because it handles coarse positioning. The tracking coil
provides the fine positioning.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

On Sun, 12 Apr 2009 14:10:52 -0700, "The Mighty T.B."
<> wrote:

>How would that relate to


**** off, kook.

On Mon, 13 Apr 2009 07:13:09 +1000, Franc Zabkar
<> wrote:

>During the 1980s I serviced Control Data disc drives to component
>level. This meant cleaning the debris from between the voice coil and
>stationery magnet of BK7 series hard drives after a head crash. This
>involved total disassembly of the affected area. I still have the
>service manuals. They refer to the part as a voice coil. Its diameter
>was the size of a CD.


And as I said already, there are other makers then and now that do NOT
refer to it that way. You are dense!

On Sun, 12 Apr 2009 15:08:00 -0700, Archimedes' Lever
<> put finger to keyboard and composed:

>On Mon, 13 Apr 2009 07:13:09 +1000, Franc Zabkar
><> wrote:
>
>>During the 1980s I serviced Control Data disc drives to component
>>level. This meant cleaning the debris from between the voice coil and
>>stationery magnet of BK7 series hard drives after a head crash. This
>>involved total disassembly of the affected area. I still have the
>>service manuals. They refer to the part as a voice coil. Its diameter
>>was the size of a CD.
>
>
> And as I said already, there are other makers then and now that do NOT
>refer to it that way. You are dense!

No, you said that your way was the *only* way.

Just to show you how ridiculous it is to rely on only *one* person's
description of a product or a technology, have a look at item 41 in
this exploded diagram of a Panasonic DMR-EX77GN DVD recorder:

http://www.prime-electronics.com.au/...DED%20VIEW.jpg

Now take a look at what Panasonic calls it:
http://www.prime-electronics.com.au/...del1=DMREX77GN

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.