WEIRD problem with CD player

[Arfa Daily]

I don't know if I will ever get this working right, but I sure am
learning a lot.

I'm sure this has to be looking for a reflection before it decides to
starts up the spindle.

I can't see the lens with the CD in. If I put a clear protective disc
in, nothing happens because it sees no reflection.

The unit is a CDP-302, a high end unit. The tag on the laser assy is
BU-1
119712

And from its construction, to replace it might cost the same as what I
paid for the unit new.

Since it will play in any position once started, is it possible the
focus/tracking drive isn't working till it starts and the at rest
position is causing the reflection to totally miss the target.

I can only imagine that to be the case if the disc was not lying flat on the
turntable for some reason. That laser part number is not familiar to me.
I'll see if I can find some service info on this player, and see if I can
think of anything else that you could reasonably try. It's reaching the
point where you have to be starting to think that it's something obscure
rather than common. An experienced eye might just look at it, and see
immediately what the trouble is. On the other hand, sometimes faults like
this can baffle even the most experienced of us.

Arfa

 

[Sam Goldwasser]

SAM
Excellent info! Thanks -

This assy appears to have the Laser and photodiode array swapped
position wise - IE array is at rt angle to the lens.

But that doesn't tell me why I can start the CD in a tilted position
then lay it flat and it will play just fine till I stop it and try to
restart it.
It will only START in the tilted position, but will continue to play
in any position. It also must be tilted on power up or insertion to
read the TOC, otherwise it won't start on "PLAY" at all.
I just can't picture anything inside the laser assy that could be that
free to move and also be controlled to lock it into position so that
it would continue to play once started.
The lens assy only rotates on the plane of the CD and doesnt appear to
have movement in the "tip" position.

DOES the array need to see anything to cause it to start?

Usually needs focus lock to start spinning the disc.

DOES it search at all by adjusting the tracking of the lens or the
array to FIND the CD?

It resets to the inner stop.

DOES the array adjust ITSELF to provide tracking?
If so how?

The entire pickup moves to do tracking.

As others have noted, with this dramatic a change, it isn't likely to be
a matter of an adjustment, or a bad cable. The servos are no longer
capable of maintaining either focus or tracking lock. These are the sort
of problems where without a service manual, it's unlikely to be repairable.
A new pickup might help, but could also be an electronics problem.

--- 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.

 

[Mark D. Zacharias]

Sam Goldwasser wrote:

The entire pickup moves to do tracking.

The entire pickup moves only when the tracking error reaches a certain
point, at which time the pickup is bumped a bit, and the tracking coils
re-center. Unless we're talking about an old Philips pivoting pickup with no
tracking coils...

But I'm pretty sure you knew this anyway.


Mark Z.

 

[Sam Goldwasser]

I can only imagine that to be the case if the disc was not lying flat on the
turntable for some reason. That laser part number is not familiar to me.
I'll see if I can find some service info on this player, and see if I can
think of anything else that you could reasonably try. It's reaching the
point where you have to be starting to think that it's something obscure
rather than common. An experienced eye might just look at it, and see
immediately what the trouble is. On the other hand, sometimes faults like
this can baffle even the most experienced of us.

I agree it may be obscure and possibly an electronic problem. There are
some differences in the part of the circuit used for the focus seach, so
your hypothesis is at least possible.

What I have done in the past to examine what's happening when it tries
to focus is to cut down a normal CD to just larger than the inner track.
One of those mini-CDs might also work. If you see the lens not moving
up and down very far, then initial focus search may be the problme.

--- 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.

 

[Sam Goldwasser]

Sam Goldwasser wrote:



The entire pickup moves only when the tracking error reaches a certain
point, at which time the pickup is bumped a bit, and the tracking coils
re-center. Unless we're talking about an old Philips pivoting pickup with no
tracking coils...

No, not those! Anything but those!

But I'm pretty sure you knew this anyway.

Right, it was in direct reponse to the original question but perhaps the
reply didn't quite make it intact.

--- 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.

 

[tomh]

Point taken on the lens fogging. It actually happened to me on one of the
first that I tried to reattach some years ago. That is why I now only use
the tiniest drop, and let it draw itself into the gap. Fuming and fogging is
then not a problem. Next time you get a missing lens, just give a Sony one a
try. If it's a lost cause already, you've got nothing further to lose !

Arfa

Hmmm, I've got a PS2 with a lens that has bubbles and scratches in it.
I was thinking about trying a lens from a compact stereo CD unit I just
shredded for parts. I realize its CD vs DVD but the lens's look the
same. As observed "got nothing further to lose !"

 

[b]

tomh ha escrito:

Hmmm, I've got a PS2 with a lens that has bubbles and scratches in it.

blimey, what do you do to it? set it on fire then put it out by
scraping it with a nailfile??!! ;-)

 

[tomh]

tomh ha escrito:


blimey, what do you do to it? set it on fire then put it out by
scraping it with a nailfile??!! ;-)

it was "broken" when I got it. The scratches I can see from somebody
previously getting in there and fooling around. Which they did. But the
bubbles they've got me stumped. If I manage to get a picture of the lens
I'll post it.

 

[Arfa Daily]

it was "broken" when I got it. The scratches I can see from somebody
previously getting in there and fooling around. Which they did. But the
bubbles they've got me stumped. If I manage to get a picture of the lens
I'll post it.

I've seen bubbled lenses from owners trying cleaning fluids, and also from
focus or tracking drive faults, which have heated up the focus or tracking
motor coils, resulting in a melted lens. It's worth trying a lens from a
different laser ( assuming that there are no drive issues that have melted
or seized the lens suspension ). I have never cross-swapped between DVD and
CD lenses, but in principle, I don't see why there should be any fundamental
difference. For any chance of success though, note carefully what I said
about making sure that every last trace of glue is removed from the lens
mount, and the replacement lens lip, before fitting it. It is essential that
the lens is //absolutely flat// in the mount.

Arfa

 

[Arfa Daily]

I agree it may be obscure and possibly an electronic problem. There are
some differences in the part of the circuit used for the focus seach, so
your hypothesis is at least possible.

What I have done in the past to examine what's happening when it tries
to focus is to cut down a normal CD to just larger than the inner track.
One of those mini-CDs might also work. If you see the lens not moving
up and down very far, then initial focus search may be the problme.

Long ago, I cut a large chunk out of an old CD with a hacksaw. That allowed
me to position the hole such that disc was over the lens, but the lens could
be seen through the hole. i don't know where that disc is now - buried
somewhere deep in the workshop no doubt. These days, I tend to just lift the
deck out, and just watch the lens action by looking under the disc or, if
you can remove the disc clamp to get good access to the top of the laser,
you can just hold a disc over the top of it at about turntable height, and
as parallel to the deck as you can manage. You can usually get the focus
servo to lock, and even 'play' with it by moving the disc up and down. It's
quite fascinating to watch the lens follow the disc as though it was stuck
there with invisible glue. I also have a circular magnet removed from a
scrap deck's disc clamp. this is very useful for sticking a disc down to the
turntable, after removing a disc clamp for eyeball access. You can also
BluTack a disc down at a pinch.

Having had a further think about this problem, could it be that something is
restricting the movement of the sled when the deck is flat ? Most players
will shuffle the laser off the home switch and back on again, just to make
sure that the laser is home, before turning on the laser and starting the
'disc in' initialisation procedure, ending in reading the TOC. If that
shuffle couldn't take place, or was being restricted in some way, then the
system control micro may not be getting the right switch signals to start it
off. If you can get the deck out in your hand whilst keeping it connected,
or otherwise get good visual access to it, try just opening and closing the
drawer, with no disc loaded, and watch exactly what happens - laser shuffle,
laser burning, focus seek etc, then try the same again with the deck tipped,
and see if you can see any difference in what happens. If not, try the same
with a disc loaded.

Arfa

 

[[email protected]]

I've tried so many things, I probably looked at that.
There is no restraint on the sled. It moves freely.
The drive belts for the table are weak, but I twisted them and it
seemed to work ok. I made sure it was fully seated when closed. It
wouldn't clamp the CD if it wasn't. I have watched it seeking track 0
but I don't remember if that was only when tipped or if it did it when
it was flat also. I believe there was no action whatever when it is
flat, but I will look again.
I can't see the lens assy from the bottom, but I will try a small CD
and see if I can view it then.

thanks.

 

[Arfa Daily]

I've tried so many things, I probably looked at that.
There is no restraint on the sled. It moves freely.
The drive belts for the table are weak, but I twisted them and it
seemed to work ok. I made sure it was fully seated when closed. It
wouldn't clamp the CD if it wasn't. I have watched it seeking track 0
but I don't remember if that was only when tipped or if it did it when
it was flat also. I believe there was no action whatever when it is
flat, but I will look again.
I can't see the lens assy from the bottom, but I will try a small CD
and see if I can view it then.

thanks.

Well, if the tray drive belt is weak, then the very first thing I would do
is to replace it. I wouldn't for one second believe with absolute certainty,
that the loading cycle is completing correctly and fully, just because the
disc appears to clamp. I have had similar situations many times, where the
final push of the mech, beyond just clamping the disc, works a "load
complete" switch, and that extra little bit of mechanical resistance from
the switch's spring loading, is just enough to hold it open. If, as you
suspect that you observed, the deck does absolutely nothing when it is flat,
then this would be a good indicator that the system control micro is waiting
for something like a "load complete" signal. In this situation, gravity may
well take over to assist the last little movement, when the deck is tipped.
This would also make sense with your assertion that once the deck has read
the TOC 'on the tip' as it were, it will then play in any position. The
system control micro only needs to be told that loading is complete, once.
Just change the belt, before going any further ...

Arfa

 

[Mark D. Zacharias]

I've seen bubbled lenses from owners trying cleaning fluids, and also
from focus or tracking drive faults, which have heated up the focus
or tracking motor coils, resulting in a melted lens. It's worth
trying a lens from a different laser ( assuming that there are no
drive issues that have melted or seized the lens suspension ). I have
never cross-swapped between DVD and CD lenses, but in principle, I
don't see why there should be any fundamental difference. For any
chance of success though, note carefully what I said about making
sure that every last trace of glue is removed from the lens mount,
and the replacement lens lip, before fitting it. It is essential that
the lens is //absolutely flat// in the mount.
Arfa

I don't think a CD lens would EVEN work on a DVD, or vice versa. The inner
curvature of the two is different, yes? DVD's have smaller pit size.

MarkZ .

 

[[email protected]]

NO, I have pushed it to be sure it is all the way in.
The tip is from side to side so gravity is not at work here. A front
to back tip will not cause it to operate.

Also, it will only CONTINUE to play in any position once play is
started. If I tip it to read the TOC then lay it flat it will not
start playing.

I HAVE discovered something else.
The sled rides on 2 rails. one side has a sleeve on it, the other
rests on a roller. It will move up about 1/16 inch on that side. If I
try to start it while flat AND holding that side up it works. Once
started, I have to let it go so the sled can move and it continues to
work.
Since that is not giving me a 45° tip, it does point to the lens or
something inside being too far off to see the reflection in its normal
position. Since it comes back at a 45° tip I have to think something
inside is loose rather than the lens gimble as that only seems to move
in the plane of the CD. HOWEVER, there isn't anything else in the assy
that moves except the lens is there??????????
THEREFORE, it has to be the lens gimble, RIGHT?????????

 

[tomh]

I don't think a CD lens would EVEN work on a DVD, or vice versa. The inner
curvature of the two is different, yes? DVD's have smaller pit size.

MarkZ .

yes point well taken. When I get both lens's out I'll check them
carefully. If they do show a remarkable difference I probably have a
dead DVD mechanism in my parts/junk pile that I can get a lens from.
will advise...

tomh

 

[Arfa Daily]

I don't think a CD lens would EVEN work on a DVD, or vice versa. The inner
curvature of the two is different, yes? DVD's have smaller pit size.

MarkZ .
I'm not sure about the potential effects of that. Might work one way round,
but not the other. A DVD laser, for instance, will happily play a CD or
VCD.

Arfa

 

[Arfa Daily]

NO, I have pushed it to be sure it is all the way in.
The tip is from side to side so gravity is not at work here. A front
to back tip will not cause it to operate.

Also, it will only CONTINUE to play in any position once play is
started. If I tip it to read the TOC then lay it flat it will not
start playing.

I HAVE discovered something else.
The sled rides on 2 rails. one side has a sleeve on it, the other
rests on a roller. It will move up about 1/16 inch on that side. If I
try to start it while flat AND holding that side up it works. Once
started, I have to let it go so the sled can move and it continues to
work.
Since that is not giving me a 45° tip, it does point to the lens or
something inside being too far off to see the reflection in its normal
position. Since it comes back at a 45° tip I have to think something
inside is loose rather than the lens gimble as that only seems to move
in the plane of the CD. HOWEVER, there isn't anything else in the assy
that moves except the lens is there??????????
THEREFORE, it has to be the lens gimble, RIGHT?????????

Weeeeeelllllll ... Not necessarily. Firstly, just because you have manually
pushed the tray all the way in, that still doesn't say that the whole
loading process has completed correctly. There is often continued movement
to complete the loading cycle, after the tray is fully home. Sometimes, for
instance, a tray lock slides into place, finally working a switch, to tell
the micro that loading really is complete. However, leaving that aside for a
moment, I think that you can be pretty sure that a 1/16th inch of vertical
play at one of the slides, is not correct. Are you absolutely sure that
something is not broken or displaced or missing from the mech at that point
? It's not uncommon for there to be a phosphor bronze finger attached to the
laser assembly, and resting under the slide rod, to take out just the sort
of play that you are describing. If it definitely works under all
circumstances with the deck flat, but that side of the laser lifted, then
logically, that must be where your problem lies, right ?

Arfa

 

[[email protected]]

Well, Tipping the deck doesn't move the the sled thru any part of that
1/16 inch, unless it is tipped past 90°. So something else on the sled
is moving when it is tipped to cause it to see a reflection.
The closed drawer position, I am sure, is not the issue.
The sled doesn't move to track zero until it sees a reflection.
I can hold it there in a position that otherwise doesn't work (flat or
tipped front to back) and it still doesn't start up.
The side that is loose appears to be designed that way. There is
nothing that would hold it top AND bottom. Gravity keep the top roller
in contact with the rail. A piece as you describe would assist gravity
to hold it in just this position. There is no adj on that roller to
make it bring the sled up. There were no loose pieces in the unit.

I might be able to jury-rig this to make the roller bigger and bring
the sled up.

 

[Mark D. Zacharias]

Arfa

That's true. Hmmm. Still, DVD players aren't optimized for CD's...

(sound effect of Markie weasling ;-)


Mark Z.

 

[Arfa Daily]

Well, Tipping the deck doesn't move the the sled thru any part of that
1/16 inch, unless it is tipped past 90°. So something else on the sled
is moving when it is tipped to cause it to see a reflection.
The closed drawer position, I am sure, is not the issue.
The sled doesn't move to track zero until it sees a reflection.
I can hold it there in a position that otherwise doesn't work (flat or
tipped front to back) and it still doesn't start up.
The side that is loose appears to be designed that way. There is
nothing that would hold it top AND bottom. Gravity keep the top roller
in contact with the rail. A piece as you describe would assist gravity
to hold it in just this position. There is no adj on that roller to
make it bring the sled up. There were no loose pieces in the unit.

I might be able to jury-rig this to make the roller bigger and bring
the sled up.

OK. I think that we have now reached the point where we have exhausted all
the normal possibilities that any of us would be able to think of with this,
which only leaves something very obscure and particular to your player.
Having tried just about everything else, I can see nothing else it can be
bar an internal defect in the laser. If taking out the play on the slide
really does provide a cure, and you're not up for the cost of replacing the
laser, which still just *may* not be the cause of the problem, then as it's
just for yourself, and not a commercial repair, now might be the time to go
for the 'technical bodge' option, as you suggest.

If the slide rod os easily removable, how about encasing it in a piece of
thin heatshrink tubing ? This would increase the effective diameter of the
rod by about the right amount, and give the roller a long life and durable
surface surface to run on.

Arfa