Hello,

I'm trying to figure out how to replace a laser diode inside a ps3 blu-
ray drive. I think I now know the best way to extract the diode.

My problem is installing the new diode; I have read in several places
that it's not simply a case of whacking the new one in, it has to be
aligned? Is this true, and if so, what would be the best way to go
about aligning it? How much is it likely to have to be rotated, i.e.
fractions of a degree or larger? I don't see that it can be rotated
that much as its degree of rotation would be limited by the flex cable
it's soldered to.

Many thanks for any help!
Nick

If the unit is well-designed, there should be no need to do anything more
than solder it in place.

However, it's likely you'll have to perform a drive-current adjustment. This
might require a special test disk and/or test equipment. The service manual
should fill you in.

"Nick Fielding" wrote in message
...
Hello,

I'm trying to figure out how to replace a laser diode inside a ps3 blu-
ray drive. I think I now know the best way to extract the diode.

My problem is installing the new diode; I have read in several places
that it's not simply a case of whacking the new one in, it has to be
aligned? Is this true, and if so, what would be the best way to go
about aligning it? How much is it likely to have to be rotated, i.e.
fractions of a degree or larger? I don't see that it can be rotated
that much as its degree of rotation would be limited by the flex cable
it's soldered to.

Many thanks for any help!
Nick

I've got a colleague who replaces many PS3 laser assemblies (I take it you
are referring to the optical head which runs on the deck within the drive,
not the *actual* laser diode ?) I will ask him what is necessary. Note also
that I think I recall him saying that there are two if not three different
variants, so make sure you get the right one. I have dismantled a number of
these drives to remove discs from PS3s suffering the YLOD condition. Be
careful when you replace the drive's top plate, as several bits of disc
handling mech, have to engage correctly with other bits on the main body of
the drive. Note also that once the top cover is removed, exposing the top
mech plate of the drive, the disc clamp just lifts away. It is not retained
by anything other than being 'sandwiched' between the mech plate and the
cover. When reassembling, it just sits on top of the (should be at that
point closed) lifter 'scissors'.

Arfa

On Oct 13, 2:38*pm, "William Sommerwerck"
wrote:
If the unit is well-designed, there should be no need to do anything more
than solder it in place.

However, it's likely you'll have to perform a drive-current adjustment. This
might require a special test disk and/or test equipment. The service manual
should fill you in.

Thanks, I've never really thought about it this way. The unit would
have to be designed in a way to make it quick to assemble and I think
it would slow things down far too much on the production line if they
had to align the laser on each unit. Also, the laser diode for this
drive is a Sony patent and is designed for this laser assembly only so
I'm guessing a drive-current adjustment won't be required either.

Thanks again for taking the time to reply.
Nick

On Oct 14, 8:48*am, "Arfa Daily" wrote:
"Nick Fielding" wrote in message

...

Hello,

I'm trying to figure out how to replace a laser diode inside a ps3 blu-
ray drive. I think I now know the best way to extract the diode.

My problem is installing the new diode; I have read in several places
that it's not simply a case of whacking the new one in, it has to be
aligned? Is this true, and if so, what would be the best way to go
about aligning it? How much is it likely to have to be rotated, i.e.
fractions of a degree or larger? I don't see that it can be rotated
that much as its degree of rotation would be limited by the flex cable
it's soldered to.

Many thanks for any help!
Nick

I've got a colleague who replaces many PS3 laser assemblies (I take it you
are referring to the optical head which runs on the deck within the drive,
not the *actual* laser diode ?) I will ask him what is necessary. Note also
that I think I recall him saying that there are two if not three different
variants, so make sure you get the right one. I have dismantled a number of
these drives to remove discs from PS3s suffering the YLOD condition. Be
careful when you replace the drive's top plate, as several bits of disc
handling mech, have to engage correctly with other bits on the main body of
the drive. Note also that once the top cover is removed, exposing the top
mech plate of the drive, the disc clamp just lifts away. It is not retained
by anything other than being 'sandwiched' between the mech plate and the
cover. When reassembling, it just sits on top of the (should be at that
point closed) lifter 'scissors'.

Arfa

Hi Arfa,

Thankyou for taking the time to reply but it's the laser diode itself
I'm working on replacing. I can replace the laser assembly no problem,
however, it's not at all economical given the price of a laser
assembly so am trying to see if I can refurbish broken assemblies by
replacing the laser diode.

Thanks,
Nick

"Nick Fielding" wrote in message
...
On Oct 14, 8:48 am, "Arfa Daily" wrote:
"Nick Fielding" wrote in message

...

Hello,

I'm trying to figure out how to replace a laser diode inside a ps3 blu-
ray drive. I think I now know the best way to extract the diode.

My problem is installing the new diode; I have read in several places
that it's not simply a case of whacking the new one in, it has to be
aligned? Is this true, and if so, what would be the best way to go
about aligning it? How much is it likely to have to be rotated, i.e.
fractions of a degree or larger? I don't see that it can be rotated
that much as its degree of rotation would be limited by the flex cable
it's soldered to.

Many thanks for any help!
Nick

I've got a colleague who replaces many PS3 laser assemblies (I take it
you
are referring to the optical head which runs on the deck within the
drive,
not the *actual* laser diode ?) I will ask him what is necessary. Note
also
that I think I recall him saying that there are two if not three
different
variants, so make sure you get the right one. I have dismantled a number
of
these drives to remove discs from PS3s suffering the YLOD condition. Be
careful when you replace the drive's top plate, as several bits of disc
handling mech, have to engage correctly with other bits on the main body
of
the drive. Note also that once the top cover is removed, exposing the top
mech plate of the drive, the disc clamp just lifts away. It is not
retained
by anything other than being 'sandwiched' between the mech plate and the
cover. When reassembling, it just sits on top of the (should be at that
point closed) lifter 'scissors'.

Arfa

Hi Arfa,

Thankyou for taking the time to reply but it's the laser diode itself
I'm working on replacing. I can replace the laser assembly no problem,
however, it's not at all economical given the price of a laser
assembly so am trying to see if I can refurbish broken assemblies by
replacing the laser diode.

Thanks,
Nick

In that case, I think you will really struggle to ever get it working again.
The laser diode is an *extremely* precision fit in the optics, aligned at
the factory in a precision jig. I once experimented with this on CD lasers,
with just about zero success. Even if I got it to read again, the
playability was poor. Ask anyone who has ever replaced a Pioneer laser just
how difficult it is to align the diffraction grating. Gnat's bollock
precision doesn't begin to describe how difficult it is to get it right, and
that's Grand Canyon versus an alleyway in terms of relative data pit size.

Given that CD optics are 'broken leg' technology, then DVD optics are in
'heart transplant' territory. Blu Ray, as PS3 lasers are, then fall into
'brain surgery' by comparison ... If the laser diode is even a vanishingly
tiny amount off-axis, the beams will not pass through the centre of the
lens, so the chances of them being reflected back from the disc correctly to
hit the pickup diodes are, IMHO, poor at best. Bear in mind also, that it is
not necessarily the laser diode that is at fault. Problems with laser
assemblies can also be down to contaminated optics - i.e. nicotine on the
critical angle mirror - a faulty pickup diode assembly, or faulty tracking /
focus coils.

I am surprised that you think that the cost of a replacement optical
assembly warrants attempting to do it by this method. According to my oppo,
the price of replacement optical heads is quite reasonable, and allows a
good margin on the job ...

You might like to look at Sam's stuff on these heads at

http://www.repairfaq.org/sam/Blu-ray/site1/optics.html

and also the material at

http://www.optoiq.com/index/photonic...ay-optics.html

which will give you a bit more of an insight into how much precision is
involved in these assemblies.

Arfa

On Oct 14, 11:32*am, "Arfa Daily" wrote:
"Nick Fielding" wrote in message

...





On Oct 14, 8:48 am, "Arfa Daily" wrote:
"Nick Fielding" wrote in message

....

Hello,

I'm trying to figure out how to replace a laser diode inside a ps3 blu-
ray drive. I think I now know the best way to extract the diode.

My problem is installing the new diode; I have read in several places
that it's not simply a case of whacking the new one in, it has to be
aligned? Is this true, and if so, what would be the best way to go
about aligning it? How much is it likely to have to be rotated, i.e.
fractions of a degree or larger? I don't see that it can be rotated
that much as its degree of rotation would be limited by the flex cable
it's soldered to.

Many thanks for any help!
Nick

I've got a colleague who replaces many PS3 laser assemblies (I take it
you
are referring to the optical head which runs on the deck within the
drive,
not the *actual* laser diode ?) I will ask him what is necessary. Note
also
that I think I recall him saying that there are two if not three
different
variants, so make sure you get the right one. I have dismantled a number
of
these drives to remove discs from PS3s suffering the YLOD condition. Be
careful when you replace the drive's top plate, as several bits of disc
handling mech, have to engage correctly with other bits on the main body
of
the drive. Note also that once the top cover is removed, exposing the top
mech plate of the drive, the disc clamp just lifts away. It is not
retained
by anything other than being 'sandwiched' between the mech plate and the
cover. When reassembling, it just sits on top of the (should be at that
point closed) lifter 'scissors'.

Arfa

Hi Arfa,

Thankyou for taking the time to reply but it's the laser diode itself
I'm working on replacing. I can replace the laser assembly no problem,
however, it's not at all economical given the price of a laser
assembly so am trying to see if I can refurbish broken assemblies by
replacing the laser diode.

Thanks,
Nick

In that case, I think you will really struggle to ever get it working again.
The laser diode is an *extremely* precision fit in the optics, aligned at
the factory in a precision jig. *I once experimented with this on CD lasers,
with just about zero success. Even if I got it to read again, the
playability was poor. Ask anyone who has ever replaced a Pioneer laser just
how difficult it is to align the diffraction grating. Gnat's bollock
precision doesn't begin to describe how difficult it is to get it right, and
that's Grand Canyon versus an alleyway in terms of relative data pit size..

Given that CD optics are 'broken leg' technology, then DVD optics are in
'heart transplant' territory. Blu Ray, as PS3 lasers are, then fall into
'brain surgery' by comparison ... *If the laser diode is even a vanishingly
tiny amount off-axis, the beams will not pass through the centre of the
lens, so the chances of them being reflected back from the disc correctly to
hit the pickup diodes are, IMHO, poor at best. Bear in mind also, that it is
not necessarily the laser diode that is at fault. Problems with laser
assemblies can also be down to contaminated optics - i.e. nicotine on the
critical angle mirror - a faulty pickup diode assembly, or faulty tracking /
focus coils.

I am surprised that you think that the cost of a replacement optical
assembly warrants attempting to do it by this method. According to my oppo,
the price of replacement optical heads is quite reasonable, and allows a
good margin on the job ...

You might like to look at Sam's stuff on these heads at

http://www.repairfaq.org/sam/Blu-ray/site1/optics.html

and also the material at

http://www.optoiq.com/index/photonic...ications/lfw-d...

which will give you a bit more of an insight into how much precision is
involved in these assemblies.

Arfa- Hide quoted text -

- Show quoted text -


That does indeed look like it requires a lot of precision.

A lens assembly costs upwards of £25 whereas a replacement laser diode
for the 410aca blu-ray drive I can get for £7. Obviously replacing the
laser diode is a fiddly and by the looks of it impossible job;
although there are people out there who are managing to do it, maybe
they have their own jig or something.

I'll probably give it a go and fail.

Many Thanks,
Nick

If the unit is well-designed, there should be no need to do anything
more than solder it in place.

However, it's likely you'll have to perform a drive-current adjustment.
This might require a special test disk and/or test equipment. The
service manual should fill you in.

Thanks, I've never really thought about it this way. The unit would
have to be designed in a way to make it quick to assemble and I think
it would slow things down far too much on the production line if they
had to align the laser on each unit. Also, the laser diode for this
drive is a Sony patent and is designed for this laser assembly only so
I'm guessing a drive-current adjustment won't be required either.


Actually, I would go with what Arfa says. What I said was "common sense" --
but probably isn't correct.

With respect to production lines... It isn't how "difficult" it is to do
something -- especially if the difficulty is reduced by the use of custom
fixtures and test equipment -- but by how long it takes. One of the reasons
"modern" electronic equipment is so much cheaper is a high level of
integration (ie, fewer parts) combined with much less human labor. And if
you can get that labor Really Cheap overseas, so much the better.

I do, however, find it hard to believe that laser-diode installation requres
extremely precise adjustments. This (to me) indicates poor product design.
Of course, I'm not omniscient in such matters.

"Nick Fielding" wrote in message
...
On Oct 14, 11:32 am, "Arfa Daily" wrote:
"Nick Fielding" wrote in message

...





On Oct 14, 8:48 am, "Arfa Daily" wrote:
"Nick Fielding" wrote in message

...

Hello,

I'm trying to figure out how to replace a laser diode inside a ps3
blu-
ray drive. I think I now know the best way to extract the diode.

My problem is installing the new diode; I have read in several
places
that it's not simply a case of whacking the new one in, it has to be
aligned? Is this true, and if so, what would be the best way to go
about aligning it? How much is it likely to have to be rotated, i.e.
fractions of a degree or larger? I don't see that it can be rotated
that much as its degree of rotation would be limited by the flex
cable
it's soldered to.

Many thanks for any help!
Nick

I've got a colleague who replaces many PS3 laser assemblies (I take it
you
are referring to the optical head which runs on the deck within the
drive,
not the *actual* laser diode ?) I will ask him what is necessary. Note
also
that I think I recall him saying that there are two if not three
different
variants, so make sure you get the right one. I have dismantled a
number
of
these drives to remove discs from PS3s suffering the YLOD condition.
Be
careful when you replace the drive's top plate, as several bits of
disc
handling mech, have to engage correctly with other bits on the main
body
of
the drive. Note also that once the top cover is removed, exposing the
top
mech plate of the drive, the disc clamp just lifts away. It is not
retained
by anything other than being 'sandwiched' between the mech plate and
the
cover. When reassembling, it just sits on top of the (should be at
that
point closed) lifter 'scissors'.

Arfa

Hi Arfa,

Thankyou for taking the time to reply but it's the laser diode itself
I'm working on replacing. I can replace the laser assembly no problem,
however, it's not at all economical given the price of a laser
assembly so am trying to see if I can refurbish broken assemblies by
replacing the laser diode.

Thanks,
Nick

In that case, I think you will really struggle to ever get it working
again.
The laser diode is an *extremely* precision fit in the optics, aligned at
the factory in a precision jig. I once experimented with this on CD
lasers,
with just about zero success. Even if I got it to read again, the
playability was poor. Ask anyone who has ever replaced a Pioneer laser
just
how difficult it is to align the diffraction grating. Gnat's bollock
precision doesn't begin to describe how difficult it is to get it right,
and
that's Grand Canyon versus an alleyway in terms of relative data pit
size.

Given that CD optics are 'broken leg' technology, then DVD optics are in
'heart transplant' territory. Blu Ray, as PS3 lasers are, then fall into
'brain surgery' by comparison ... If the laser diode is even a
vanishingly
tiny amount off-axis, the beams will not pass through the centre of the
lens, so the chances of them being reflected back from the disc correctly
to
hit the pickup diodes are, IMHO, poor at best. Bear in mind also, that it
is
not necessarily the laser diode that is at fault. Problems with laser
assemblies can also be down to contaminated optics - i.e. nicotine on the
critical angle mirror - a faulty pickup diode assembly, or faulty
tracking /
focus coils.

I am surprised that you think that the cost of a replacement optical
assembly warrants attempting to do it by this method. According to my
oppo,
the price of replacement optical heads is quite reasonable, and allows a
good margin on the job ...

You might like to look at Sam's stuff on these heads at

http://www.repairfaq.org/sam/Blu-ray/site1/optics.html

and also the material at

http://www.optoiq.com/index/photonic...ications/lfw-d...

which will give you a bit more of an insight into how much precision is
involved in these assemblies.

Arfa- Hide quoted text -

- Show quoted text -


That does indeed look like it requires a lot of precision.

A lens assembly costs upwards of £25 whereas a replacement laser diode
for the 410aca blu-ray drive I can get for £7. Obviously replacing the
laser diode is a fiddly and by the looks of it impossible job;
although there are people out there who are managing to do it, maybe
they have their own jig or something.

I'll probably give it a go and fail.

Many Thanks,
Nick

As for people claiming to be able to do this job, treat the claims with
caution. There are many people offering 'guaranteed solutions' to for
instance the YLOD problem, and indeed they do appear to work - at least
initially. The trick is that they only seem to last long enough to dispose
of the unit claiming it to be a 'worker' ...

The minimum independant commercial repair cost for a PS3 is around 80 quid.
My friend charges £120 to replace a laser, and he has no shortage of takers.
Sony charge 180 quid for a service exchange PS3, and the cost of a new (pre
latest slimline version) PS3 is around £300. Non-workers go on eBay for
anything up to £90, and working examples for a lot more than that, so I
think that there is potentially enough margin in laser replacement to
warrant not having to mess around trying to repair the laser assembly -
given that the bulk of the cost is the labour you will have already put in
to strip the PS3 and its drive. and then remove the laser anyway to attempt
the diode replacement ....

Don't forget to be careful not to lose the little bent piece of metal that
the Torx screw that holds the top cover goes into. Only valid for Mk1's of
course, the screw going into a moulding on Mk2's and 3's.

Good luck. If you do attempt it, do let us know (honestly !!) how it goes,
as I am an interested party on PS3 repairs.

Arfa

On Oct 14, 2:22*pm, "Arfa Daily" wrote:
"Nick Fielding" wrote in message

...





On Oct 14, 11:32 am, "Arfa Daily" wrote:
"Nick Fielding" wrote in message

....

On Oct 14, 8:48 am, "Arfa Daily" wrote:
"Nick Fielding" wrote in message

...

Hello,

I'm trying to figure out how to replace a laser diode inside a ps3
blu-
ray drive. I think I now know the best way to extract the diode.

My problem is installing the new diode; I have read in several
places
that it's not simply a case of whacking the new one in, it has to be
aligned? Is this true, and if so, what would be the best way to go
about aligning it? How much is it likely to have to be rotated, i..e.
fractions of a degree or larger? I don't see that it can be rotated
that much as its degree of rotation would be limited by the flex
cable
it's soldered to.

Many thanks for any help!
Nick

I've got a colleague who replaces many PS3 laser assemblies (I take it
you
are referring to the optical head which runs on the deck within the
drive,
not the *actual* laser diode ?) I will ask him what is necessary. Note
also
that I think I recall him saying that there are two if not three
different
variants, so make sure you get the right one. I have dismantled a
number
of
these drives to remove discs from PS3s suffering the YLOD condition..
Be
careful when you replace the drive's top plate, as several bits of
disc
handling mech, have to engage correctly with other bits on the main
body
of
the drive. Note also that once the top cover is removed, exposing the
top
mech plate of the drive, the disc clamp just lifts away. It is not
retained
by anything other than being 'sandwiched' between the mech plate and
the
cover. When reassembling, it just sits on top of the (should be at
that
point closed) lifter 'scissors'.

Arfa

Hi Arfa,

Thankyou for taking the time to reply but it's the laser diode itself
I'm working on replacing. I can replace the laser assembly no problem,
however, it's not at all economical given the price of a laser
assembly so am trying to see if I can refurbish broken assemblies by
replacing the laser diode.

Thanks,
Nick

In that case, I think you will really struggle to ever get it working
again.
The laser diode is an *extremely* precision fit in the optics, aligned at
the factory in a precision jig. *I once experimented with this on CD
lasers,
with just about zero success. Even if I got it to read again, the
playability was poor. Ask anyone who has ever replaced a Pioneer laser
just
how difficult it is to align the diffraction grating. Gnat's bollock
precision doesn't begin to describe how difficult it is to get it right,
and
that's Grand Canyon versus an alleyway in terms of relative data pit
size.

Given that CD optics are 'broken leg' technology, then DVD optics are in
'heart transplant' territory. Blu Ray, as PS3 lasers are, then fall into
'brain surgery' by comparison ... *If the laser diode is even a
vanishingly
tiny amount off-axis, the beams will not pass through the centre of the
lens, so the chances of them being reflected back from the disc correctly
to
hit the pickup diodes are, IMHO, poor at best. Bear in mind also, that it
is
not necessarily the laser diode that is at fault. Problems with laser
assemblies can also be down to contaminated optics - i.e. nicotine on the
critical angle mirror - a faulty pickup diode assembly, or faulty
tracking /
focus coils.

I am surprised that you think that the cost of a replacement optical
assembly warrants attempting to do it by this method. According to my
oppo,
the price of replacement optical heads is quite reasonable, and allows a
good margin on the job ...

You might like to look at Sam's stuff on these heads at

http://www.repairfaq.org/sam/Blu-ray/site1/optics.html

and also the material at

http://www.optoiq.com/index/photonic...ications/lfw-d....

which will give you a bit more of an insight into how much precision is
involved in these assemblies.

Arfa- Hide quoted text -

- Show quoted text -

That does indeed look like it requires a lot of precision.

A lens assembly costs upwards of £25 whereas a replacement laser diode
for the 410aca blu-ray drive I can get for £7. Obviously replacing the
laser diode is a fiddly and by the looks of it impossible job;
although there are people out there who are managing to do it, maybe
they have their own jig or something.

I'll probably give it a go and fail.

Many Thanks,
Nick

As for people claiming to be able to do this job, treat the claims with
caution. There are many people offering 'guaranteed solutions' to for
instance the YLOD problem, and indeed they do appear to work - at least
initially. The trick is that they only seem to last long enough to dispose
of the unit claiming it to be a 'worker' ...

The minimum independant commercial repair cost for a PS3 is around 80 quid.
My friend charges £120 to replace a laser, and he has no shortage of takers.
Sony charge 180 quid for a service exchange PS3, and the cost of a new (pre
latest slimline version) PS3 is around £300. Non-workers go on eBay for
anything up to £90, and working examples for a lot more than that, so I
think that there is potentially enough margin in laser replacement to
warrant not having to mess around trying to repair the laser assembly -
given that the bulk of the cost is the labour you will have already put in
to strip the PS3 and its drive. and then remove the laser anyway to attempt
the diode replacement ....

Don't forget to be careful not to lose the little bent piece of metal that
the Torx screw that holds the top cover goes into. Only valid for Mk1's of
course, the screw going into a moulding on Mk2's and 3's.

Good luck. If you do attempt it, do let us know (honestly !!) how it goes,
as I am an interested party on PS3 repairs.

Arfa- Hide quoted text -

- Show quoted text -

I'll definitely give it a go and let you know how it goes, probably
won't be for a little while yet as I have a number of PS3s which I
have waiting to be sold first.

Thanks both for your replies, I really should remember to use
newsgroups more as the people on here just seem much more intelligent
and I always get useful replies unlike on most web forums.

Thanks!
Nick

"William Sommerwerck" wrote in message
...
If the unit is well-designed, there should be no need to do anything
more than solder it in place.

However, it's likely you'll have to perform a drive-current adjustment.
This might require a special test disk and/or test equipment. The
service manual should fill you in.

Thanks, I've never really thought about it this way. The unit would
have to be designed in a way to make it quick to assemble and I think
it would slow things down far too much on the production line if they
had to align the laser on each unit. Also, the laser diode for this
drive is a Sony patent and is designed for this laser assembly only so
I'm guessing a drive-current adjustment won't be required either.


Actually, I would go with what Arfa says. What I said was "common
sense" --
but probably isn't correct.

With respect to production lines... It isn't how "difficult" it is to do
something -- especially if the difficulty is reduced by the use of custom
fixtures and test equipment -- but by how long it takes. One of the
reasons
"modern" electronic equipment is so much cheaper is a high level of
integration (ie, fewer parts) combined with much less human labor. And if
you can get that labor Really Cheap overseas, so much the better.

I do, however, find it hard to believe that laser-diode installation
requres
extremely precise adjustments. This (to me) indicates poor product design.
Of course, I'm not omniscient in such matters.



The laser diode itself (in my experience) has a flat, unfocused lens. The
focusing, grating, etc comes in later. I have successfully replaced laser
diodes but as Arfa says, the problem is often not the diode itself, but
other problems in the optic path.
One symptom of a failing laser diode (on conventional DVD players) seems to
be a situation where the unit plays OK for perhaps 15 minutes to 1/2 hour,
then starts skipping, pausing, pixelizing, etc. As the laser diode warms up,
emission declines, and soon the bit errors exceed the error correction
capability of the electronics. Less critical on an audio CD, but seems to
reach a fatal level pretty quickly in DVD players, and I assume BD players
may be even more critical - though I've yet to have much experience on
those.

Mark Z.

"William Sommerwerck" wrote in message
...
If the unit is well-designed, there should be no need to do anything
more than solder it in place.

However, it's likely you'll have to perform a drive-current adjustment.
This might require a special test disk and/or test equipment. The
service manual should fill you in.

Thanks, I've never really thought about it this way. The unit would
have to be designed in a way to make it quick to assemble and I think
it would slow things down far too much on the production line if they
had to align the laser on each unit. Also, the laser diode for this
drive is a Sony patent and is designed for this laser assembly only so
I'm guessing a drive-current adjustment won't be required either.


Actually, I would go with what Arfa says. What I said was "common
sense" --
but probably isn't correct.

With respect to production lines... It isn't how "difficult" it is to do
something -- especially if the difficulty is reduced by the use of custom
fixtures and test equipment -- but by how long it takes. One of the
reasons
"modern" electronic equipment is so much cheaper is a high level of
integration (ie, fewer parts) combined with much less human labor. And if
you can get that labor Really Cheap overseas, so much the better.

I do, however, find it hard to believe that laser-diode installation
requres
extremely precise adjustments. This (to me) indicates poor product design.
Of course, I'm not omniscient in such matters.



I'm not sure that a requirement for precision of assembly, necessarily
indicates poor design. Let's take the example of video heads for a moment.
The ferrite head chips were mounted in brass carriers that were just screwed
to the head drum, so you might imagine that they would be replaceable.
However, such was the level of precision that was required to correctly
position these heads, it was not possible to do outside of the factory
environment, where I guess the job was made staggeringly easy by appropriate
positioning jigs, and automated assembly processes. There was actually one
company in the UK that did re-head drums, but the machine that they had to
do this was very expensive, and required a skilled operator. So, because
video head drums required this level of assembly precision, did that make
them a bad idea or a poor design ? I don't actually think so.

To be honest, I doubt whether the accuracy required in positioning the
actual laser diode comes close to that required for the pickup array, and
they manage to do that ok at the factory. As Mark Z suggests further down,
all of the critical optics follow the laser diode, and rotational accuracy
should not be an issue. Where I feel that you would have to be very careful,
is in getting the diode properly on-axis. If this is off by the tiniest
amount, the beam will not pass through the following optics at the places
that it is designed to. the error will become cumulative, the further you go
down the optical path. You might get away with this on a CD laser, but I'm
not sure that you would with a DVD laser. Given that the optics of a BluRay
laser are further complicated by the precision harmonic filter behind the
objective lens, any such error may well put the optical block's performance
below the required minimum for reliable operation.

I suppose that it could be argued that the tracking and / or focus servos
may be able to compensate, but these servos should be action-neutral, and if
the servos have to compensate for a mechanical error in the beam position,
by storing a non-neutral compensation value, then this compromises the
integrity of the whole system, by restricting the servo range that's left.

Arfa