Att'n: Kurtis (and/or other gurus) Re: 'Alignment'

[Guest]

Archived from groups: alt.video.laserdisc (More info?)

I've hung around these parts for a good long while now, and I've never
really cared what "alignment" really is or does, but I find that I now
care enough about LD output quality to notice my CLD-D925 appears to
be giving me a bit of checkerboard / dot crawl trouble.

Now, I guess partly I can blame comb filtering, and I've already
started to look into how to bypass the internal ADC and comb filter in
favour of an external capture device. But I've also read that poor
alignment -- of something; perhaps the laser? -- may also be to blame
for checkerboard-type patterns.

I took the cover off the 925 to have a look inside, and I see quite a
little forest of potentiometers that appear to invite twisting. But I
don't want to touch anything until I know what I'm doing -- or at
least *think* I know what I'm doing.

So, my questions are, What's alignment, How is it done, What sort of
symtoms can it fix, What do I need to get started, and/or Who can do
it for me?

Thanks!

 

[Guest]

Archived from groups: alt.video.laserdisc (More info?)

If you are seeing dot crawl and checkerboard patterns, that is a NTSC
problem. Not sure if you are watching PAL or NTSC LD's. The way to reduce
the NTSC dot crawl is to connect the composite output to an adaptive filter
which can help with this. The LD-S9, CLD-99, CLD-D99, HLD-X9, CLD-R7G are
machines which have adaptive filter but non of them play PAL LD's. The
CLD-99 is an American model and the others are all Japanese, there are a
couple other Japanese model also.

The alignments are more for crosstalk noise where you see herringbone
patterns at various places on the screen and they can get background noise
to it's lowest performance for that design.

Kurtis

"Karyudo" <karyudo_usenet@yahoo.com.remove.me> wrote in message
news099t0l01n7tgomemj4dq3dcl60bv1ihkp@4ax.com...
> I've hung around these parts for a good long while now, and I've never
> really cared what "alignment" really is or does, but I find that I now
> care enough about LD output quality to notice my CLD-D925 appears to
> be giving me a bit of checkerboard / dot crawl trouble.
>
> Now, I guess partly I can blame comb filtering, and I've already
> started to look into how to bypass the internal ADC and comb filter in
> favour of an external capture device. But I've also read that poor
> alignment -- of something; perhaps the laser? -- may also be to blame
> for checkerboard-type patterns.
>
> I took the cover off the 925 to have a look inside, and I see quite a
> little forest of potentiometers that appear to invite twisting. But I
> don't want to touch anything until I know what I'm doing -- or at
> least *think* I know what I'm doing.
>
> So, my questions are, What's alignment, How is it done, What sort of
> symtoms can it fix, What do I need to get started, and/or Who can do
> it for me?
>
> Thanks!

 

[Guest]

Archived from groups: alt.video.laserdisc (More info?)

Karyudo wrote:
> Have you got a reference to a site where I might see some example
> pictures (for herringbone, etc.)?

I don't have a site handy, but I know a herringbone pattern when I see
one. The pattern reminds you of Charlie Brown's chevron shirt turned
on its side constantly flittering about.

I don't know if the Crystal Vision VPS-1 or the Faroudja VP-100 work on
PAL signals, but if they do, they should both remove the dot
crawl/checkerboard artifacts.

<http/www.hometheaterhifi.com/volume_5_1/crystalvision.html>
<http/www.hometheaterhifi.com/volume_4_2/faroudja100.html>

-Junior

 

[Guest]

Archived from groups: alt.video.laserdisc (More info?)

On Fri, 31 Dec 2004 01:57:06 -0500, "Kurtis Bahr" <kbahr@comcast.net>
wrote:

>If you are seeing dot crawl and checkerboard patterns, that is a NTSC
>problem. Not sure if you are watching PAL or NTSC LD's.

I'm watching PAL LD's, and still seeing what I'm seeing. PAL is still
interlaced, so aren't dot crawl and checkerboards still possible? Or
is the internal comb filter not doing a great job (i.e. making things
worse in small, localized areas)? If you'd like to see a picture, I
can post one someplace...

I know that if I want the best possible NTSC performance, I've bought
the wrong player. But for the best possible PAL performance, I think
I've gotten one of the two best! Haven't I?

>The alignments are more for crosstalk noise where you see herringbone
>patterns at various places on the screen and they can get background noise
>to its lowest performance for that design.

Have you got a reference to a site where I might see some example
pictures (for herringbone, etc.)?

Also, a sort of rhetorical, unanswerable question: How do I know if
I'm looking at the lowest possible background noise for the 925
design? I'd have to go through the alignment process, wouldn't I?

In order to absolutely optimize picture quality, what sorts of other
tweaks and hacks might be possible? I thought I read about various
shields, and maybe even swapping out of some power components in
high-end players like the X0. What things should I be looking into
first (in general)?

 

[Guest]

Archived from groups: alt.video.laserdisc (More info?)

I have never worked on PAL players so I cannot speak from experience. But
crosstalk will be more like areas with wavy line. It will not correspond to
the current view as it is actually data from an adjacent ring of recorded
data on the LD. One test is done by playing a CAV recorded LD. Since the
information from ring to ring is the same there is no crosstalk. If you see
the problems with CAV recorded LD's then it most likely is not crosstalk.

Kurtis

"Karyudo" <karyudo_usenet@yahoo.com.remove.me> wrote in message
news10at0lk56p5haocp31ccqvfab2021819n@4ax.com...
> On Fri, 31 Dec 2004 01:57:06 -0500, "Kurtis Bahr" <kbahr@comcast.net>
> wrote:
>
>>If you are seeing dot crawl and checkerboard patterns, that is a NTSC
>>problem. Not sure if you are watching PAL or NTSC LD's.
>
> I'm watching PAL LD's, and still seeing what I'm seeing. PAL is still
> interlaced, so aren't dot crawl and checkerboards still possible? Or
> is the internal comb filter not doing a great job (i.e. making things
> worse in small, localized areas)? If you'd like to see a picture, I
> can post one someplace...
>
> I know that if I want the best possible NTSC performance, I've bought
> the wrong player. But for the best possible PAL performance, I think
> I've gotten one of the two best! Haven't I?
>
>>The alignments are more for crosstalk noise where you see herringbone
>>patterns at various places on the screen and they can get background noise
>>to its lowest performance for that design.
>
> Have you got a reference to a site where I might see some example
> pictures (for herringbone, etc.)?
>
> Also, a sort of rhetorical, unanswerable question: How do I know if
> I'm looking at the lowest possible background noise for the 925
> design? I'd have to go through the alignment process, wouldn't I?
>
> In order to absolutely optimize picture quality, what sorts of other
> tweaks and hacks might be possible? I thought I read about various
> shields, and maybe even swapping out of some power components in
> high-end players like the X0. What things should I be looking into
> first (in general)?

 

[Guest]

Archived from groups: alt.video.laserdisc (More info?)

On Sat, 1 Jan 2005 00:55:56 -0500, "Kurtis Bahr" <kbahr@comcast.net>
wrote:

>Since the
>information from ring to ring is the same there is no crosstalk. If you see
>the problems with CAV recorded LD's then it most likely is not crosstalk.

That makes sense. The problems I'm seeing *are* from a CAV PAL disc,
so I guess that pretty much rules out crosstalk. That's good on the
one hand (one less thing to worry about), but not so great on the
other, since it means whatever I'm seeing still doesn't have a
definitive cause or solution. Oh, well: I'll keep reading. Thanks for
your help!