My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter than
it normally does...

wrote in message
...
My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter than
it normally does...

I think that it is highly unlikely that anything is happening to the size of
any gear wheels. The (very brief) sound that can be heard on your clip,
sounds like the motor pinion slipping against the intermediate drive gear.
On a typical mech that uses any of the KSS series lasers, the most common
cause of this is bad contacts on the laser 'home' switch, normally located
on the spindle / sled motor connection board, right underneath the
turntable. When the contacts don't make very well, the laser homes as
normal, but no signal is generated when it gets there, to tell the system
control micro to shut off the drive to the motor, so it keeps running, and
the gears slip against one another. After a while, the vibration caused by
this often gets the switch contacts to make again briefly, which then causes
the drive to be cut. My first move would be to clean the switch.

Arfa

On Feb 8, 11:49*am, "Arfa Daily" wrote:
wrote in message

...

My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. *I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? *The system gets no hotter than
it normally does...

I think that it is highly unlikely that anything is happening to the size of
any gear wheels. The (very brief) sound that can be heard on your clip,
sounds like the motor pinion slipping against the intermediate drive gear.
On a typical mech that uses any of the KSS series lasers, the most common
cause of this is bad contacts on the laser 'home' switch, normally located
on the spindle / sled motor connection board, right underneath the
turntable. When the contacts don't make very well, the laser homes as
normal, but no signal is generated when it gets there, to tell the system
control micro to shut off the drive to the motor, so it keeps running, and
the gears slip against one another. After a while, the vibration caused by
this often gets the switch contacts to make again briefly, which then causes
the drive to be cut. My first move would be to clean the switch.

Arfa

This sounds like a better theory than mine. lol

The sound seems to more occur when the Sega CD stops an audio track
and goes to read data, so I guess it needs to return home to read the
TOC to find the data it wants.

Thing is, it happens ONLY when warm. When the machine is cold, it
never has this issue.

I'll give it a cleaning, though it's hard to get to that home switch
(i know where it is).. Hopefully getting the assembly out will be
easier than I fear..

On Feb 8, 11:49*am, "Arfa Daily" wrote:
wrote in message

...

My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. *I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? *The system gets no hotter than
it normally does...

I think that it is highly unlikely that anything is happening to the size of
any gear wheels. The (very brief) sound that can be heard on your clip,
sounds like the motor pinion slipping against the intermediate drive gear.
On a typical mech that uses any of the KSS series lasers, the most common
cause of this is bad contacts on the laser 'home' switch, normally located
on the spindle / sled motor connection board, right underneath the
turntable. When the contacts don't make very well, the laser homes as
normal, but no signal is generated when it gets there, to tell the system
control micro to shut off the drive to the motor, so it keeps running, and
the gears slip against one another. After a while, the vibration caused by
this often gets the switch contacts to make again briefly, which then causes
the drive to be cut. My first move would be to clean the switch.

Arfa

An update: I watched the laser move, and when it screeches, it's not
even near the home switch.. The motor spins, and the cogwheel does
move, but misses on the other gear (it never slips on the sled)...

There's a decent amount of play, because if I manually turn the
cogwheel, it does sometime miss too..

writes:

On Feb 8, 11:49*am, "Arfa Daily" wrote:
wrote in message

...

My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. *I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? *The system gets no hotter than
it normally does...

I think that it is highly unlikely that anything is happening to the size of
any gear wheels. The (very brief) sound that can be heard on your clip,
sounds like the motor pinion slipping against the intermediate drive gear.
On a typical mech that uses any of the KSS series lasers, the most common
cause of this is bad contacts on the laser 'home' switch, normally located
on the spindle / sled motor connection board, right underneath the
turntable. When the contacts don't make very well, the laser homes as
normal, but no signal is generated when it gets there, to tell the system
control micro to shut off the drive to the motor, so it keeps running, and
the gears slip against one another. After a while, the vibration caused by
this often gets the switch contacts to make again briefly, which then causes
the drive to be cut. My first move would be to clean the switch.

Arfa

An update: I watched the laser move, and when it screeches, it's not
even near the home switch.. The motor spins, and the cogwheel does
move, but misses on the other gear (it never slips on the sled)...

There's a decent amount of play, because if I manually turn the
cogwheel, it does sometime miss too..

Do you need to find out why there's free play. There may be enough
free play for it slip or jump gears if something is binding, but not
otherwise. Does the sled move freely on the rails?

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

wrote in message
...
On Feb 8, 11:49 am, "Arfa Daily" wrote:
wrote in message

...

My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter than
it normally does...

I think that it is highly unlikely that anything is happening to the size
of
any gear wheels. The (very brief) sound that can be heard on your clip,
sounds like the motor pinion slipping against the intermediate drive gear.
On a typical mech that uses any of the KSS series lasers, the most common
cause of this is bad contacts on the laser 'home' switch, normally located
on the spindle / sled motor connection board, right underneath the
turntable. When the contacts don't make very well, the laser homes as
normal, but no signal is generated when it gets there, to tell the system
control micro to shut off the drive to the motor, so it keeps running, and
the gears slip against one another. After a while, the vibration caused by
this often gets the switch contacts to make again briefly, which then
causes
the drive to be cut. My first move would be to clean the switch.

Arfa

An update: I watched the laser move, and when it screeches, it's not
even near the home switch.. The motor spins, and the cogwheel does
move, but misses on the other gear (it never slips on the sled)...

There's a decent amount of play, because if I manually turn the
cogwheel, it does sometime miss too..


Thinking about it, there was an issue with some Sony decks (which this
almost certainly is) with two of the gears being right at either end of
their size tolerance specifications, and there was a mod kit for it with two
new gears. There was a service bulletin about it, as I recall, but I
wouldn't know where to lay hands on it now. If you have a local hifi repair
shop, they will have scrap Sony decks coming out of their ears, as many
warranty replacement lasers were supplied by Sony as whole KSM series decks.
You should be able to get a scrap deck from them, which may not be exactly
the same, but in general, the gears in the sled drive train are, so you can
rob and transplant them into your deck. The other alternative is a bit of a
'bodge'. You can slacken the screws which secure the sled motor, then push a
thin sliver of plastic sheet under the side of the motor closest to the
intermediate gear. When you tighten the screws back up, the motor will have
a very slight 'tilt' towards the intermediate gear, which will improve the
meshing. Not ideal, but I have done similar things in the past, when parts
have not been available, or have been prohibitively expensive.

Arfa

On Feb 8, 7:26 pm, "Arfa Daily" wrote:
wrote in message

...
On Feb 8, 11:49 am, "Arfa Daily" wrote:



wrote in message

...

My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter than
it normally does...

I think that it is highly unlikely that anything is happening to the size
of
any gear wheels. The (very brief) sound that can be heard on your clip,
sounds like the motor pinion slipping against the intermediate drive gear.
On a typical mech that uses any of the KSS series lasers, the most common
cause of this is bad contacts on the laser 'home' switch, normally located
on the spindle / sled motor connection board, right underneath the
turntable. When the contacts don't make very well, the laser homes as
normal, but no signal is generated when it gets there, to tell the system
control micro to shut off the drive to the motor, so it keeps running, and
the gears slip against one another. After a while, the vibration caused by
this often gets the switch contacts to make again briefly, which then
causes
the drive to be cut. My first move would be to clean the switch.

Arfa
An update: I watched the laser move, and when it screeches, it's not
even near the home switch.. The motor spins, and the cogwheel does
move, but misses on the other gear (it never slips on the sled)...
There's a decent amount of play, because if I manually turn the
cogwheel, it does sometime miss too..

Thinking about it, there was an issue with some Sony decks (which this
almost certainly is) with two of the gears being right at either end of
their size tolerance specifications, and there was a mod kit for it with two
new gears. There was a service bulletin about it, as I recall, but I
wouldn't know where to lay hands on it now. If you have a local hifi repair
shop, they will have scrap Sony decks coming out of their ears, as many
warranty replacement lasers were supplied by Sony as whole KSM series decks.
You should be able to get a scrap deck from them, which may not be exactly
the same, but in general, the gears in the sled drive train are, so you can
rob and transplant them into your deck. The other alternative is a bit of a
'bodge'. You can slacken the screws which secure the sled motor, then push a
thin sliver of plastic sheet under the side of the motor closest to the
intermediate gear. When you tighten the screws back up, the motor will have
a very slight 'tilt' towards the intermediate gear, which will improve the
meshing. Not ideal, but I have done similar things in the past, when parts
have not been available, or have been prohibitively expensive.

Arfa

I will check at a local repair center and see if they have one..

Btw, I took the "drive" out, and noticed the home switch did have a
cold solder joint, i fixed it, but no change..

http://img.photobucket.com/albums/v3...gon/cdmech.jpg
http://img.photobucket.com/albums/v3...ragon/cold.jpg

I have an old Sony, and peeking in, it has a KSS 210B drive. Can that
work? Or is it not compatible?

wrote in message
...
On Feb 8, 7:26 pm, "Arfa Daily" wrote:
wrote in message

...
On Feb 8, 11:49 am, "Arfa Daily" wrote:



wrote in message

...

My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter than
it normally does...

I think that it is highly unlikely that anything is happening to the
size
of
any gear wheels. The (very brief) sound that can be heard on your clip,
sounds like the motor pinion slipping against the intermediate drive
gear.
On a typical mech that uses any of the KSS series lasers, the most
common
cause of this is bad contacts on the laser 'home' switch, normally
located
on the spindle / sled motor connection board, right underneath the
turntable. When the contacts don't make very well, the laser homes as
normal, but no signal is generated when it gets there, to tell the
system
control micro to shut off the drive to the motor, so it keeps running,
and
the gears slip against one another. After a while, the vibration caused
by
this often gets the switch contacts to make again briefly, which then
causes
the drive to be cut. My first move would be to clean the switch.

Arfa
An update: I watched the laser move, and when it screeches, it's not
even near the home switch.. The motor spins, and the cogwheel does
move, but misses on the other gear (it never slips on the sled)...
There's a decent amount of play, because if I manually turn the
cogwheel, it does sometime miss too..

Thinking about it, there was an issue with some Sony decks (which this
almost certainly is) with two of the gears being right at either end of
their size tolerance specifications, and there was a mod kit for it with
two
new gears. There was a service bulletin about it, as I recall, but I
wouldn't know where to lay hands on it now. If you have a local hifi
repair
shop, they will have scrap Sony decks coming out of their ears, as many
warranty replacement lasers were supplied by Sony as whole KSM series
decks.
You should be able to get a scrap deck from them, which may not be
exactly
the same, but in general, the gears in the sled drive train are, so you
can
rob and transplant them into your deck. The other alternative is a bit of
a
'bodge'. You can slacken the screws which secure the sled motor, then
push a
thin sliver of plastic sheet under the side of the motor closest to the
intermediate gear. When you tighten the screws back up, the motor will
have
a very slight 'tilt' towards the intermediate gear, which will improve
the
meshing. Not ideal, but I have done similar things in the past, when
parts
have not been available, or have been prohibitively expensive.

Arfa

I will check at a local repair center and see if they have one..

Btw, I took the "drive" out, and noticed the home switch did have a
cold solder joint, i fixed it, but no change..

http://img.photobucket.com/albums/v3...gon/cdmech.jpg
http://img.photobucket.com/albums/v3...ragon/cold.jpg

I have an old Sony, and peeking in, it has a KSS 210B drive. Can that
work? Or is it not compatible?

The '210 laser is completely incompatible with the '240 - different
connectors for one thing. For sure, the 240 will fit on the 210 deck - the
body shape of both lasers is the same. However, the decks themselves are
quite likely to be different. They may have the mounting rubbers in slightly
different places, or the actual shape of the metal deck may be subtly
different, for instance. They may have different shaft lengths on the
spindle motor, and differently designed turntables, which have to match the
disc clamp. There are a number of variations of these decks, many of which
look the same at a first glance, but are different when you dig in a bit
deeper. However, most of then share the same drive chain gears for the sled,
so you may be able to cull parts that will do the job, off that '210 deck
that you have found.

Arfa

On Feb 8, 8:55 pm, "Arfa Daily" wrote:
wrote in message

...



On Feb 8, 7:26 pm, "Arfa Daily" wrote:
wrote in message

...
On Feb 8, 11:49 am, "Arfa Daily" wrote:

wrote in message

...

My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter than
it normally does...

I think that it is highly unlikely that anything is happening to the
size
of
any gear wheels. The (very brief) sound that can be heard on your clip,
sounds like the motor pinion slipping against the intermediate drive
gear.
On a typical mech that uses any of the KSS series lasers, the most
common
cause of this is bad contacts on the laser 'home' switch, normally
located
on the spindle / sled motor connection board, right underneath the
turntable. When the contacts don't make very well, the laser homes as
normal, but no signal is generated when it gets there, to tell the
system
control micro to shut off the drive to the motor, so it keeps running,
and
the gears slip against one another. After a while, the vibration caused
by
this often gets the switch contacts to make again briefly, which then
causes
the drive to be cut. My first move would be to clean the switch.

Arfa
An update: I watched the laser move, and when it screeches, it's not
even near the home switch.. The motor spins, and the cogwheel does
move, but misses on the other gear (it never slips on the sled)...
There's a decent amount of play, because if I manually turn the
cogwheel, it does sometime miss too..

Thinking about it, there was an issue with some Sony decks (which this
almost certainly is) with two of the gears being right at either end of
their size tolerance specifications, and there was a mod kit for it with
two
new gears. There was a service bulletin about it, as I recall, but I
wouldn't know where to lay hands on it now. If you have a local hifi
repair
shop, they will have scrap Sony decks coming out of their ears, as many
warranty replacement lasers were supplied by Sony as whole KSM series
decks.
You should be able to get a scrap deck from them, which may not be
exactly
the same, but in general, the gears in the sled drive train are, so you
can
rob and transplant them into your deck. The other alternative is a bit of
a
'bodge'. You can slacken the screws which secure the sled motor, then
push a
thin sliver of plastic sheet under the side of the motor closest to the
intermediate gear. When you tighten the screws back up, the motor will
have
a very slight 'tilt' towards the intermediate gear, which will improve
the
meshing. Not ideal, but I have done similar things in the past, when
parts
have not been available, or have been prohibitively expensive.

Arfa

I will check at a local repair center and see if they have one..

Btw, I took the "drive" out, and noticed the home switch did have a
cold solder joint, i fixed it, but no change..

http://img.photobucket.com/albums/v3...gon/cdmech.jpg
http://img.photobucket.com/albums/v3...ragon/cold.jpg

I have an old Sony, and peeking in, it has a KSS 210B drive. Can that
work? Or is it not compatible?

The '210 laser is completely incompatible with the '240 - different
connectors for one thing. For sure, the 240 will fit on the 210 deck - the
body shape of both lasers is the same. However, the decks themselves are
quite likely to be different. They may have the mounting rubbers in slightly
different places, or the actual shape of the metal deck may be subtly
different, for instance. They may have different shaft lengths on the
spindle motor, and differently designed turntables, which have to match the
disc clamp. There are a number of variations of these decks, many of which
look the same at a first glance, but are different when you dig in a bit
deeper. However, most of then share the same drive chain gears for the sled,
so you may be able to cull parts that will do the job, off that '210 deck
that you have found.

Arfa

Ok.

The Sega CD's desk doesn't have any rubber at all, it's hinged at the
back, and at the front, as a piece that attaches to a gear that's run
on the tray, so when the tray closes, the desk pops up into position.
The spot where rubber pieces go at the 4 corners, is actually some
brass colored bolt, which is secured to a fairly large PCB at the
bottom.. The only cable going to the Sega CD's motherboard, is a big
flat ribbon on the right side of the PCB on the deck.

I will check all my old CD-players for gears that fit.

Btw, side question: I noticed when the 240a is reading a music CD, it
is 1x as it should be.. But when it reads data, it does spin the CD
faster, but not quite 2x.. Sega claims it's 1x read only, and from
what I see, the 240a is 1x only. So why does it spin faster for data?

wrote in message
...
On Feb 8, 8:55 pm, "Arfa Daily" wrote:
wrote in message

...



On Feb 8, 7:26 pm, "Arfa Daily" wrote:
wrote in message

...
On Feb 8, 11:49 am, "Arfa Daily" wrote:

wrote in message

...

My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel
is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter
than
it normally does...

I think that it is highly unlikely that anything is happening to the
size
of
any gear wheels. The (very brief) sound that can be heard on your
clip,
sounds like the motor pinion slipping against the intermediate drive
gear.
On a typical mech that uses any of the KSS series lasers, the most
common
cause of this is bad contacts on the laser 'home' switch, normally
located
on the spindle / sled motor connection board, right underneath the
turntable. When the contacts don't make very well, the laser homes
as
normal, but no signal is generated when it gets there, to tell the
system
control micro to shut off the drive to the motor, so it keeps
running,
and
the gears slip against one another. After a while, the vibration
caused
by
this often gets the switch contacts to make again briefly, which
then
causes
the drive to be cut. My first move would be to clean the switch.

Arfa
An update: I watched the laser move, and when it screeches, it's not
even near the home switch.. The motor spins, and the cogwheel does
move, but misses on the other gear (it never slips on the sled)...
There's a decent amount of play, because if I manually turn the
cogwheel, it does sometime miss too..

Thinking about it, there was an issue with some Sony decks (which this
almost certainly is) with two of the gears being right at either end
of
their size tolerance specifications, and there was a mod kit for it
with
two
new gears. There was a service bulletin about it, as I recall, but I
wouldn't know where to lay hands on it now. If you have a local hifi
repair
shop, they will have scrap Sony decks coming out of their ears, as
many
warranty replacement lasers were supplied by Sony as whole KSM series
decks.
You should be able to get a scrap deck from them, which may not be
exactly
the same, but in general, the gears in the sled drive train are, so
you
can
rob and transplant them into your deck. The other alternative is a bit
of
a
'bodge'. You can slacken the screws which secure the sled motor, then
push a
thin sliver of plastic sheet under the side of the motor closest to
the
intermediate gear. When you tighten the screws back up, the motor will
have
a very slight 'tilt' towards the intermediate gear, which will improve
the
meshing. Not ideal, but I have done similar things in the past, when
parts
have not been available, or have been prohibitively expensive.

Arfa

I will check at a local repair center and see if they have one..

Btw, I took the "drive" out, and noticed the home switch did have a
cold solder joint, i fixed it, but no change..

http://img.photobucket.com/albums/v3...gon/cdmech.jpg
http://img.photobucket.com/albums/v3...ragon/cold.jpg

I have an old Sony, and peeking in, it has a KSS 210B drive. Can that
work? Or is it not compatible?

The '210 laser is completely incompatible with the '240 - different
connectors for one thing. For sure, the 240 will fit on the 210 deck -
the
body shape of both lasers is the same. However, the decks themselves are
quite likely to be different. They may have the mounting rubbers in
slightly
different places, or the actual shape of the metal deck may be subtly
different, for instance. They may have different shaft lengths on the
spindle motor, and differently designed turntables, which have to match
the
disc clamp. There are a number of variations of these decks, many of
which
look the same at a first glance, but are different when you dig in a bit
deeper. However, most of then share the same drive chain gears for the
sled,
so you may be able to cull parts that will do the job, off that '210 deck
that you have found.

Arfa

Ok.

The Sega CD's desk doesn't have any rubber at all, it's hinged at the
back, and at the front, as a piece that attaches to a gear that's run
on the tray, so when the tray closes, the desk pops up into position.
The spot where rubber pieces go at the 4 corners, is actually some
brass colored bolt, which is secured to a fairly large PCB at the
bottom.. The only cable going to the Sega CD's motherboard, is a big
flat ribbon on the right side of the PCB on the deck.


The actual metal deck likely still has the corner rubbers, as these form the
primary shock-resistant suspension system for it. The hinged plastic tray
that is worked from the lifter gear driven off the drawer gears, is just a
carrier for the deck. It is a common arrangement. It is also common for the
rubbers to collapse over time, which can lead to a very tap-sensitive
system, which might lead you to suspect a bad laser. The laser itself will
connect to that sub pcb on the '210 deck'd machine that you have found. The
connections to a '210 are two multi-pin sockets with conventional wires. The
'240 has a single narrow-ish white ribbon.


I will check all my old CD-players for gears that fit.

Btw, side question: I noticed when the 240a is reading a music CD, it
is 1x as it should be.. But when it reads data, it does spin the CD
faster, but not quite 2x.. Sega claims it's 1x read only, and from
what I see, the 240a is 1x only. So why does it spin faster for data?

I've no idea, really. I have seen 'conventional' audio lasers such as the
KSS series, being run at higher than x1 in 'specialist' audio applications,
so it seems that they are capable of it. The decks in personal CD players
often run the disc at x2 or more in an effort to keep the bit bucket full
for anti-shock purposes, but since the Sega is not subject to physical shock
(!) that's obviously not the reason. Might be something to do with keeping a
larger buffer of data available though, due to processing speed or something
?

Arfa

wrote:
My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter than
it normally does...

Hello,

One other thought that others have not mentioned. I've seen a failure
of the clock circuit being fed to the mechanism fail and cause the laser
sled to go flying to the outside if the disc and the sled drive will
keep going. If left in this condition, it will actually grind the rack
on the laser to bits.

I've never had one that was intermittent, but if the clock was
beginning to fail, I guess it might do it for a short burst. If this is
the case, then the sled is likely to be at the extreme outside edge of
the disc.

The machine that I've seen this on it the Arcam Alpha 8, and the Alpha
8SE CD players. A surface mount transistor on the DAC board clock
circuit was running to hot and would fail. When it did, the sled drive
would force the laser to the extreme outside and make a horrible
ratcheting noise. There was a production change to prevent this. I've NO
IDEA if this is possible on your Sega player.

Regards,
Tim Schwartz
Bristol Electronics

On Feb 9, 5:18 am, "Arfa Daily" wrote:
wrote in message

...



On Feb 8, 8:55 pm, "Arfa Daily" wrote:
wrote in message

...

On Feb 8, 7:26 pm, "Arfa Daily" wrote:
wrote in message

...
On Feb 8, 11:49 am, "Arfa Daily" wrote:

wrote in message

...

My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel
is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter
than
it normally does...

I think that it is highly unlikely that anything is happening to the
size
of
any gear wheels. The (very brief) sound that can be heard on your
clip,
sounds like the motor pinion slipping against the intermediate drive
gear.
On a typical mech that uses any of the KSS series lasers, the most
common
cause of this is bad contacts on the laser 'home' switch, normally
located
on the spindle / sled motor connection board, right underneath the
turntable. When the contacts don't make very well, the laser homes
as
normal, but no signal is generated when it gets there, to tell the
system
control micro to shut off the drive to the motor, so it keeps
running,
and
the gears slip against one another. After a while, the vibration
caused
by
this often gets the switch contacts to make again briefly, which
then
causes
the drive to be cut. My first move would be to clean the switch.

Arfa
An update: I watched the laser move, and when it screeches, it's not
even near the home switch.. The motor spins, and the cogwheel does
move, but misses on the other gear (it never slips on the sled)...
There's a decent amount of play, because if I manually turn the
cogwheel, it does sometime miss too..

Thinking about it, there was an issue with some Sony decks (which this
almost certainly is) with two of the gears being right at either end
of
their size tolerance specifications, and there was a mod kit for it
with
two
new gears. There was a service bulletin about it, as I recall, but I
wouldn't know where to lay hands on it now. If you have a local hifi
repair
shop, they will have scrap Sony decks coming out of their ears, as
many
warranty replacement lasers were supplied by Sony as whole KSM series
decks.
You should be able to get a scrap deck from them, which may not be
exactly
the same, but in general, the gears in the sled drive train are, so
you
can
rob and transplant them into your deck. The other alternative is a bit
of
a
'bodge'. You can slacken the screws which secure the sled motor, then
push a
thin sliver of plastic sheet under the side of the motor closest to
the
intermediate gear. When you tighten the screws back up, the motor will
have
a very slight 'tilt' towards the intermediate gear, which will improve
the
meshing. Not ideal, but I have done similar things in the past, when
parts
have not been available, or have been prohibitively expensive.

Arfa

I will check at a local repair center and see if they have one..

Btw, I took the "drive" out, and noticed the home switch did have a
cold solder joint, i fixed it, but no change..

http://img.photobucket.com/albums/v3...gon/cdmech.jpg
http://img.photobucket.com/albums/v3...ragon/cold.jpg

I have an old Sony, and peeking in, it has a KSS 210B drive. Can that
work? Or is it not compatible?

The '210 laser is completely incompatible with the '240 - different
connectors for one thing. For sure, the 240 will fit on the 210 deck -
the
body shape of both lasers is the same. However, the decks themselves are
quite likely to be different. They may have the mounting rubbers in
slightly
different places, or the actual shape of the metal deck may be subtly
different, for instance. They may have different shaft lengths on the
spindle motor, and differently designed turntables, which have to match
the
disc clamp. There are a number of variations of these decks, many of
which
look the same at a first glance, but are different when you dig in a bit
deeper. However, most of then share the same drive chain gears for the
sled,
so you may be able to cull parts that will do the job, off that '210 deck
that you have found.

Arfa

Ok.

The Sega CD's desk doesn't have any rubber at all, it's hinged at the
back, and at the front, as a piece that attaches to a gear that's run
on the tray, so when the tray closes, the desk pops up into position.
The spot where rubber pieces go at the 4 corners, is actually some
brass colored bolt, which is secured to a fairly large PCB at the
bottom.. The only cable going to the Sega CD's motherboard, is a big
flat ribbon on the right side of the PCB on the deck.

The actual metal deck likely still has the corner rubbers, as these form the
primary shock-resistant suspension system for it. The hinged plastic tray
that is worked from the lifter gear driven off the drawer gears, is just a
carrier for the deck. It is a common arrangement. It is also common for the
rubbers to collapse over time, which can lead to a very tap-sensitive
system, which might lead you to suspect a bad laser. The laser itself will
connect to that sub pcb on the '210 deck'd machine that you have found. The
connections to a '210 are two multi-pin sockets with conventional wires. The
'240 has a single narrow-ish white ribbon.



I will check all my old CD-players for gears that fit.

Btw, side question: I noticed when the 240a is reading a music CD, it
is 1x as it should be.. But when it reads data, it does spin the CD
faster, but not quite 2x.. Sega claims it's 1x read only, and from
what I see, the 240a is 1x only. So why does it spin faster for data?

I've no idea, really. I have seen 'conventional' audio lasers such as the
KSS series, being run at higher than x1 in 'specialist' audio applications,
so it seems that they are capable of it. The decks in personal CD players
often run the disc at x2 or more in an effort to keep the bit bucket full
for anti-shock purposes, but since the Sega is not subject to physical shock
(!) that's obviously not the reason. Might be something to do with keeping a
larger buffer of data available though, due to processing speed or something
?

Arfa

After playing with the game console last night (and falling asleep,
lol), I noticed a trend... It's grinding gears isn't so intermittent
as I thought.

Batman and Robbin: When going from the title screen to the Options
menu, it grinds gears. Also when going from Options to Title Screen,
it also grinds gears.
Sonic CD: In Time Trial screen, selecting a level grinds gears as
soon as it starts to load a level.

Oddly, all three times it grinds gears on "command", was when it was
playing a CD audio redbook track, and went to reading data (on track
"1")..

This is leading me to confusion, because home switch is fine, i tested
it, resoldered it, cleaned it, and it seems that it's the action of
throwing the laser closer to the spindle... (the start of the
movement, not the "stopping")..

After playing with the game console last night (and falling asleep,
lol), I noticed a trend... It's grinding gears isn't so intermittent
as I thought.

Batman and Robbin: When going from the title screen to the Options
menu, it grinds gears. Also when going from Options to Title Screen,
it also grinds gears.
Sonic CD: In Time Trial screen, selecting a level grinds gears as
soon as it starts to load a level.

Oddly, all three times it grinds gears on "command", was when it was
playing a CD audio redbook track, and went to reading data (on track
"1")..

This is leading me to confusion, because home switch is fine, i tested
it, resoldered it, cleaned it, and it seems that it's the action of
throwing the laser closer to the spindle... (the start of the
movement, not the "stopping")..

Well, I guess it's just when the thing needs to move the sled somewhere else
in a hurry. The play in the gears allows them to slip momentarily as the
motor tries to accelerate the optical block. I wouldn't say that it is any
kind of real 'mystery' to lose sleep over. Just find some replacement gears,
or tilt the motor, and I'm sure it will be fine.

Arfa

"Tim Schwartz" wrote in message
...
wrote:
My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter than
it normally does...

Hello,

One other thought that others have not mentioned. I've seen a failure of
the clock circuit being fed to the mechanism fail and cause the laser sled
to go flying to the outside if the disc and the sled drive will keep
going. If left in this condition, it will actually grind the rack on the
laser to bits.

I've never had one that was intermittent, but if the clock was beginning
to fail, I guess it might do it for a short burst. If this is the case,
then the sled is likely to be at the extreme outside edge of the disc.

The machine that I've seen this on it the Arcam Alpha 8, and the Alpha 8SE
CD players. A surface mount transistor on the DAC board clock circuit was
running to hot and would fail. When it did, the sled drive would force
the laser to the extreme outside and make a horrible ratcheting noise.
There was a production change to prevent this. I've NO IDEA if this is
possible on your Sega player.

Regards,
Tim Schwartz
Bristol Electronics


Hello Tim. Yes, I've seen a similar problem to that as well, but I can't
remember what it was on. As I recall, it chewed the teeth right off the
motor pinion. From what I can gather, this one doesn't seem to do it at
either end of the sled. Seems to be more when it starts to move the sled
from any position, so probably a mechanical issue.

Arfa

On Feb 9, 2:02 pm, "Arfa Daily" wrote:
After playing with the game console last night (and falling asleep,
lol), I noticed a trend... It's grinding gears isn't so intermittent
as I thought.

Batman and Robbin: When going from the title screen to the Options
menu, it grinds gears. Also when going from Options to Title Screen,
it also grinds gears.
Sonic CD: In Time Trial screen, selecting a level grinds gears as
soon as it starts to load a level.

Oddly, all three times it grinds gears on "command", was when it was
playing a CD audio redbook track, and went to reading data (on track
"1")..

This is leading me to confusion, because home switch is fine, i tested
it, resoldered it, cleaned it, and it seems that it's the action of
throwing the laser closer to the spindle... (the start of the
movement, not the "stopping")..

Well, I guess it's just when the thing needs to move the sled somewhere else
in a hurry. The play in the gears allows them to slip momentarily as the
motor tries to accelerate the optical block. I wouldn't say that it is any
kind of real 'mystery' to lose sleep over. Just find some replacement gears,
or tilt the motor, and I'm sure it will be fine.

Arfa

Ahh, that did it.. When the Sega CD is tilted slightly clockwise, the
grinding stops completely..

I will hunt gears then..

Thanks!

On Sat, 09 Feb 2008 13:24:12 GMT, Tim Schwartz
put finger to keyboard and composed:

wrote:
My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter than
it normally does...

Hello,

One other thought that others have not mentioned. I've seen a failure
of the clock circuit being fed to the mechanism fail and cause the laser
sled to go flying to the outside if the disc and the sled drive will
keep going. If left in this condition, it will actually grind the rack
on the laser to bits.

Wasn't the KSS-240A also susceptible to oscillation problems and
wasn't there a kit that fixed this?

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

On Feb 9, 10:24*pm, Franc Zabkar wrote:
On Sat, 09 Feb 2008 13:24:12 GMT, Tim Schwartz
put finger to keyboard and composed:



wrote:
My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. *I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? *The system gets no hotter than
it normally does...

Hello,

* *One other thought that others have not mentioned. *I've seen a failure
of the clock circuit being fed to the mechanism fail and cause the laser
sled to go flying to the outside if the disc and the sled drive will
keep going. *If left in this condition, it will actually grind the rack
on the laser to bits.

Wasn't the KSS-240A also susceptible to oscillation problems and
wasn't there a kit that fixed this?

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

This isn't an oscillation problem, and it seems SEGA put brass weights
on the assembly already.

Franc Zabkar writes:

On Sat, 09 Feb 2008 13:24:12 GMT, Tim Schwartz
put finger to keyboard and composed:

wrote:
My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter than
it normally does...

Hello,

One other thought that others have not mentioned. I've seen a failure
of the clock circuit being fed to the mechanism fail and cause the laser
sled to go flying to the outside if the disc and the sled drive will
keep going. If left in this condition, it will actually grind the rack
on the laser to bits.

Wasn't the KSS-240A also susceptible to oscillation problems and
wasn't there a kit that fixed this?

Yes, seems to be an unrelated problem though.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

On Feb 9, 2:06*pm, "Arfa Daily" wrote:
"Tim Schwartz" wrote in message

...

wrote:
My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. *I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? *The system gets no hotter than
it normally does...

Hello,

One other thought that others have not mentioned. *I've seen a failure of
the clock circuit being fed to the mechanism fail and cause the laser sled
to go flying to the outside if the disc and the sled drive will keep
going. *If left in this condition, it will actually grind the rack on the
laser to bits.

I've never had one that was intermittent, but if the clock was beginning
to fail, I guess it might do it for a short burst. *If this is the case,
then the sled is likely to be at the extreme outside edge of the disc.

The machine that I've seen this on it the Arcam Alpha 8, and the Alpha 8SE
CD players. *A surface mount transistor on the DAC board clock circuit was
running to hot and would fail. *When it did, the sled drive would force
the laser to the extreme outside and make a horrible ratcheting noise.
There was a production change to prevent this. I've NO IDEA if this is
possible on your Sega player.

Regards,
Tim Schwartz
Bristol Electronics

Hello Tim. Yes, I've seen a similar problem to that as well, but I can't
remember what it was on. As I recall, it chewed the teeth right off the
motor pinion. From what I can gather, this one doesn't seem to do it at
either end of the sled. Seems to be more when it starts to move the sled
from any position, so probably a mechanical issue.

Arfa

It's probably too late and Arfa won't see this, but I brought my whole
Sega CD to a repair shop, and he was able to reproduce the problem
when COLD.

With a scope, he discovered that the CD-ROM drive is in "seek" mode
when playing video games, hence the disc spins faster. Possibly to
boost transfer rate for the games "Full Motion Video".

Also, he discovered the grinding will ONLY occur when the drive is in
it's "1.5x" mode, as when playing music CD's, the grinding was
impossible to produce.

Solution: He has a replacement mech where the laser and PCB will
happily attach, and the Sega CD doesn't even know a different mech is
installed. Only downside: Tray is now white, and not black. ehh..
As long as it works..

wrote in message
...
On Feb 9, 2:06 pm, "Arfa Daily" wrote:
"Tim Schwartz" wrote in message

...

wrote:
My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter than
it normally does...

Hello,

One other thought that others have not mentioned. I've seen a failure of
the clock circuit being fed to the mechanism fail and cause the laser
sled
to go flying to the outside if the disc and the sled drive will keep
going. If left in this condition, it will actually grind the rack on the
laser to bits.

I've never had one that was intermittent, but if the clock was beginning
to fail, I guess it might do it for a short burst. If this is the case,
then the sled is likely to be at the extreme outside edge of the disc.

The machine that I've seen this on it the Arcam Alpha 8, and the Alpha
8SE
CD players. A surface mount transistor on the DAC board clock circuit
was
running to hot and would fail. When it did, the sled drive would force
the laser to the extreme outside and make a horrible ratcheting noise.
There was a production change to prevent this. I've NO IDEA if this is
possible on your Sega player.

Regards,
Tim Schwartz
Bristol Electronics

Hello Tim. Yes, I've seen a similar problem to that as well, but I can't
remember what it was on. As I recall, it chewed the teeth right off the
motor pinion. From what I can gather, this one doesn't seem to do it at
either end of the sled. Seems to be more when it starts to move the sled
from any position, so probably a mechanical issue.

Arfa

It's probably too late and Arfa won't see this, but I brought my whole
Sega CD to a repair shop, and he was able to reproduce the problem
when COLD.

With a scope, he discovered that the CD-ROM drive is in "seek" mode
when playing video games, hence the disc spins faster. Possibly to
boost transfer rate for the games "Full Motion Video".

Also, he discovered the grinding will ONLY occur when the drive is in
it's "1.5x" mode, as when playing music CD's, the grinding was
impossible to produce.

Solution: He has a replacement mech where the laser and PCB will
happily attach, and the Sega CD doesn't even know a different mech is
installed. Only downside: Tray is now white, and not black. ehh..
As long as it works..

Good result then !

Arfa

On Feb 11, 4:05*am, "Arfa Daily" wrote:
wrote in message

...
On Feb 9, 2:06 pm, "Arfa Daily" wrote:



"Tim Schwartz" wrote in message

...

wrote:
My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..

http://www.youtube.com/watch?v=U55FF7NLgn4

Any ideas on how to actually fix this? The system gets no hotter than
it normally does...

Hello,

One other thought that others have not mentioned. I've seen a failure of
the clock circuit being fed to the mechanism fail and cause the laser
sled
to go flying to the outside if the disc and the sled drive will keep
going. If left in this condition, it will actually grind the rack on the
laser to bits.

I've never had one that was intermittent, but if the clock was beginning
to fail, I guess it might do it for a short burst. If this is the case,
then the sled is likely to be at the extreme outside edge of the disc.

The machine that I've seen this on it the Arcam Alpha 8, and the Alpha
8SE
CD players. A surface mount transistor on the DAC board clock circuit
was
running to hot and would fail. When it did, the sled drive would force
the laser to the extreme outside and make a horrible ratcheting noise.
There was a production change to prevent this. I've NO IDEA if this is
possible on your Sega player.

Regards,
Tim Schwartz
Bristol Electronics

Hello Tim. Yes, I've seen a similar problem to that as well, but I can't
remember what it was on. As I recall, it chewed the teeth right off the
motor pinion. From what I can gather, this one doesn't seem to do it at
either end of the sled. Seems to be more when it starts to move the sled
from any position, so probably a mechanical issue.

Arfa

It's probably too late and Arfa won't see this, but I brought my whole
Sega CD to a repair shop, and he was able to reproduce the problem
when COLD.

With a scope, he discovered that the CD-ROM drive is in "seek" mode
when playing video games, hence the disc spins faster. *Possibly to
boost transfer rate for the games "Full Motion Video".

Also, he discovered the grinding will ONLY occur when the drive is in
it's "1.5x" mode, as when playing music CD's, the grinding was
impossible to produce.

Solution: *He has a replacement mech where the laser and PCB will
happily attach, and the Sega CD doesn't even know a different mech is
installed. *Only downside: *Tray is now white, and not black. *ehh..
As long as it works..

Good result then !

Arfa

PS: You don't think it would be stupid, for me to use my Sega CD as
my CD audio player? It does have great audio qualities, and it's
actually my only system in my theater, that can play CD's at such a
good quality. (even my HTPC can't compete!)

With specs like this:
16 bit DAC
8x internal over-sampling digital filter
Frequency Range: 20 Hz - 20 kHz
Signal-to-Noise Ratio: 90.0 dB @ 1K
Channel Separation: 90.0 dB

I assume that's good, because it sounds good.

It's probably too late and Arfa won't see this, but I brought my whole
Sega CD to a repair shop, and he was able to reproduce the problem
when COLD.

With a scope, he discovered that the CD-ROM drive is in "seek" mode
when playing video games, hence the disc spins faster. Possibly to
boost transfer rate for the games "Full Motion Video".

Also, he discovered the grinding will ONLY occur when the drive is in
it's "1.5x" mode, as when playing music CD's, the grinding was
impossible to produce.

Solution: He has a replacement mech where the laser and PCB will
happily attach, and the Sega CD doesn't even know a different mech is
installed. Only downside: Tray is now white, and not black. ehh..
As long as it works..

Good result then !

Arfa

PS: You don't think it would be stupid, for me to use my Sega CD as
my CD audio player? It does have great audio qualities, and it's
actually my only system in my theater, that can play CD's at such a
good quality. (even my HTPC can't compete!)

With specs like this:
16 bit DAC
8x internal over-sampling digital filter
Frequency Range: 20 Hz - 20 kHz
Signal-to-Noise Ratio: 90.0 dB @ 1K
Channel Separation: 90.0 dB

I assume that's good, because it sounds good.


I see no reason not to. Its spec looks much the same as most regular
players. Many players of a few years back, used the KSS240A laser. It's a
reasonably long-lived and reliable type, so no issues there.

Arfa

On Mon, 11 Feb 2008 09:05:24 GMT, "Arfa Daily"
put finger to keyboard and composed:

wrote in message
...

Solution: He has a replacement mech where the laser and PCB will
happily attach, and the Sega CD doesn't even know a different mech is
installed. Only downside: Tray is now white, and not black. ehh..
As long as it works..

Good result then !

Arfa

FYI, when you use OE to reply to a message that has been encoded in
"quoted printable" format, then OE fails to quote it properly. I'm not
sure, but I believe the following utility may fix this bug:

http://home.in.tum.de/~jain/software/outlook-quotefix/

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