Panasonic CD-Player SL-S120 help with realignment

R

Rainer F. Daltrop

Guest
Hi
I am doing a charity repair of Panasonic portable CD-Player SL-S120
and need some data for realignment procedure. Poor thing came in with
all controls severely tampered; Wiper on VCC adj pot gone, alignment
screws on optical pickup were tightened, yet Laser power adj seems
untouched.
Fault found and repaired was open tracking coil; one suspension wire
at lens assy had broken free.
I managed to replace the destroyed pot and without service data
adjusted VCC (voltage after the stepup regulator) to 3.3V (wiper
slightly below midrange of VCC control range; 3V - 4V). I readjusted
the mechanical tilt of the lens to enable tracking and focus but the
Unit skips track occasionally and is very susceptive to even slightest
movements.
Could anyone look up the VCC setting on that model and enlighten me if
there is a simple way to adjust the mechanical alignment of the lens
assy? Any procedure that can be followed without special Test-Disc? If
I set mechanical alignment to produce maximum voltage of the eye
pattern (with laser power untouched) the skipping of tracks gets
better, but the unit gets more susceptive to vibrations.

Thanks
Rainer
 
flintstone0183@hotmail.com (Rainer F. Daltrop) writes:

Hi
I am doing a charity repair of Panasonic portable CD-Player SL-S120
and need some data for realignment procedure. Poor thing came in with
all controls severely tampered; Wiper on VCC adj pot gone, alignment
screws on optical pickup were tightened, yet Laser power adj seems
untouched.
Fault found and repaired was open tracking coil; one suspension wire
at lens assy had broken free.
I managed to replace the destroyed pot and without service data
adjusted VCC (voltage after the stepup regulator) to 3.3V (wiper
slightly below midrange of VCC control range; 3V - 4V). I readjusted
the mechanical tilt of the lens to enable tracking and focus but the
Unit skips track occasionally and is very susceptive to even slightest
movements.
Could anyone look up the VCC setting on that model and enlighten me if
there is a simple way to adjust the mechanical alignment of the lens
assy? Any procedure that can be followed without special Test-Disc? If
I set mechanical alignment to produce maximum voltage of the eye
pattern (with laser power untouched) the skipping of tracks gets
better, but the unit gets more susceptive to vibrations.
Click to expand...
Does reducing VCC to say 3 V make any difference? My guess is that it isn't
a VCC issue. I assume you've cleaned the lens and any other optics you
can get at?

How do you know laser power pot is untouched?

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the Feedback Form at repairfaq.org. Thanks.
 
Hi Sam
Thanks for your answer...

Does reducing VCC to say 3 V make any difference?
Click to expand...
At the lowest possible value (~2.9V) the player fails reading the TOC
after initial focus search and it may even go into power off mode
during TOC access. Same if I reduce voltage after spinup during play
and try to jump a track.
Up to 3.2-3.5V (midrange) the behaviour improves significantly,
reaches current state. At max (4.1V) the coil driver chip heats up
noticeably but no significant improvement.

My guess is that it isn't a VCC issue.
Click to expand...
I tend to agree to that. But having it set to the proper value should
at least give some peace of mind. For now I will go with 3.3V -
Objections?

I assume you've cleaned the lens and any other optics you can get at?
Click to expand...
Top of lens only. To fix the tracking coil there was no need to remove
the lens assy and I opted not to make things worse by disassembling
down to the turning mirror and stuff .

How do you know laser power pot is untouched?
Click to expand...
Although it is an open case SMD pot located on the side of the pickup
it is secured with some white laquer.

If I adjust the lens tilt for best performance I have a sharp
eyepattern of almost stable height at ~0.8Vpp and the player skips
occasionally. But if I adjust the lens tilt to provides the strongest
eyepattern (~1Vpp) the scope shows noise in the pattern and a general
change of RF packet height along with the revolution of the disc
(though the disc itself does not wobble) - the player may even fail to
readthe TOC or jump to the first track. What I cannot understand is
why the voltage of the eye pattern is higher on the noisy setting
which produces the worest performance. While OTOH the sharpest
eyepattern and best performance produces a smaller pattern. Shouldn't
best player performace, sharpest eyepattern and highest voltage of the
eyepattern converge on one single setting?

-Rainer
 
I'd assume setting the mechanical alignment of the pickup for best
performance would be the best (and only) option with the test gear you
probably have at hand. If it was a 3 beam pickup (which I am quite
sure of) and RF was derived from the center photodetectors A-D only,
the scope on the RF Packet would not give you any clue if the outer
photodetectors E and F have get clean signal -and AFAIK they are the
ones responsible for tracking. And remember that Pickup was toyed
with, so you do not know if it can be aligned properly at all.
The problem of random skipping may also be caused by a worn out motor
bearing even though you say the disc would not appear to have
excessive run out - so scope the tracking and focus signal for high
signals repeating along with the turning of the disc and try to
replace the motor on trial and error basis if possible. And since it
is a portable do also check the clamp on the disc platter. IIRC this
is the one with the button on top to be pressed to release and popup
the disk- one of the springy clamps on the holder may have been bent
or the disc slips.
OTOH given the state the player was in I'd say you are pretty lucky
you got it working at all.

-Melissa

Rainer F. Daltrop wrote:

If I adjust the lens tilt for best performance I have a sharp
eyepattern of almost stable height at ~0.8Vpp and the player skips
occasionally. But if I adjust the lens tilt to provides the strongest
eyepattern (~1Vpp) the scope shows noise in the pattern and a general
change of RF packet height along with the revolution of the disc
(though the disc itself does not wobble) - the player may even fail to
readthe TOC or jump to the first track.
Click to expand...
 
Don't try to realign a laser pickup unless it's been abused! They are
unlikely to go out of alignment under normal use.

A dirty lens or other optics and mechanical problems are much more likely.

--- sam | Sci.Electronics.Repair FAQ Home Page: 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 Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the Feedback Form at repairfaq.org. Thanks.



meschnei@gmx.net (Melissa) writes:

I'd assume setting the mechanical alignment of the pickup for best
performance would be the best (and only) option with the test gear you
probably have at hand. If it was a 3 beam pickup (which I am quite
sure of) and RF was derived from the center photodetectors A-D only,
the scope on the RF Packet would not give you any clue if the outer
photodetectors E and F have get clean signal -and AFAIK they are the
ones responsible for tracking. And remember that Pickup was toyed
with, so you do not know if it can be aligned properly at all.
The problem of random skipping may also be caused by a worn out motor
bearing even though you say the disc would not appear to have
excessive run out - so scope the tracking and focus signal for high
signals repeating along with the turning of the disc and try to
replace the motor on trial and error basis if possible. And since it
is a portable do also check the clamp on the disc platter. IIRC this
is the one with the button on top to be pressed to release and popup
the disk- one of the springy clamps on the holder may have been bent
or the disc slips.
OTOH given the state the player was in I'd say you are pretty lucky
you got it working at all.

-Melissa

Rainer F. Daltrop wrote:

If I adjust the lens tilt for best performance I have a sharp
eyepattern of almost stable height at ~0.8Vpp and the player skips
occasionally. But if I adjust the lens tilt to provides the strongest
eyepattern (~1Vpp) the scope shows noise in the pattern and a general
change of RF packet height along with the revolution of the disc
(though the disc itself does not wobble) - the player may even fail to
readthe TOC or jump to the first track.
Click to expand...
 
"Sam Goldwasser" <sam@saul.cis.upenn.edu> wrote
Don't try to realign a laser pickup unless it's been abused! They are
unlikely to go out of alignment under normal use.

A dirty lens or other optics and mechanical problems are much more likely.
Click to expand...
As I stated before in this thread the pickup was tampered with and I had to
realign it to get it going at all. Of course I would not have touched it
otherwise.

-Rainer
 
To Melissa:
Thanks for that hint. The disc does not seem to suffer from runout - based
my visual inspection via calibrated fingernail and on your explanation that
run-out should show as shift of the tracking/focus signal along with the
revolution of the disc. One thing though I noticed: at the moment of
skipping I can scope a peak or sometimes multiple peaks in the spindle motor
voltage. But I don't know how to interpret this voltage peak. Going by the
tests that are described in Sam's CD FAQ and turning the motor by hand while
measuring the resistance at the motor terminals shows 6.5-7.3Ohms
continously. As for applying an external voltage this proves rather
fruitless since my precision in regulating the voltage is poorer than the
capabilities of the inbuilt electronics and I produce a lot more skipping as
the skipping I intend to cure, which may occur once every 3 to 5 mins once I
set the optical alignment (note to Sam: which was definitely way off when I
got the unit) to optimum performance as you suggested.
I guess I have to bite the bullet and replace the motor - except that I feel
unsure about mangling the platter the disc resides on. There isnt much room
to insert pliers to strip the platter from the axle without bending the
outer perimeter of the platter...

-Rainer

"Melissa" wrote...
(snipped)
signals repeating along with the turning of the disc and try to
replace the motor on trial and error basis if possible. And since it
is a portable do also check the clamp on the disc platter. IIRC this
is the one with the button on top to be pressed to release and popup
the disk- one of the springy clamps on the holder may have been bent
or the disc slips.
Click to expand...
 
What type of skipping is it? Short distance, long distance, or just
a repeat or dropout?

--- sam | Sci.Electronics.Repair FAQ Home Page: 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 Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the Feedback Form at repairfaq.org. Thanks.
 
Hi Sam

In general it is a short distance skip as if it would jump from one groove
to the immediate neighbor without delay. Most of the time this skip will
cause a repeat sometimes an advance. The best analogy would perhaps be that
of an old turntable skipping on a slightly scratched record but without
going into looped repeat.
The second sort of skips is does covers the same short distance as said
above but incorporates a slight delay of about half a second or so. Or
speaking in terms of ancient turntables; it seems like someone lifts the
pickup for the fraction of a second off the record and puts it back down.

-Rainer

"Sam Goldwasser" wrote

What type of skipping is it? Short distance, long distance, or just
a repeat or dropout?

--- sam | Sci.Electronics.Repair FAQ Home Page: 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 Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work.
To
contact me, please use the Feedback Form at repairfaq.org. Thanks.
Click to expand...
 
Obviously clean the lens if you have not done so.
Also, recent vintage Panasonics use a wormscrew drive for the pickup. The
tolerances are tight, and the least bit of hair or carpet fiber will tend to
jam them up. Yours could be in a borderline mech jamming condition involving
the wormscrew (sled) drive.


Mark Z.



"Rainer F. Daltrop" <flintstone0183@hotmail.com> wrote in message
news:bn3b7t$scten$1@ID-210863.news.uni-berlin.de...
Hi Sam

In general it is a short distance skip as if it would jump from one groove
to the immediate neighbor without delay. Most of the time this skip will
cause a repeat sometimes an advance. The best analogy would perhaps be
that
of an old turntable skipping on a slightly scratched record but without
going into looped repeat.
The second sort of skips is does covers the same short distance as said
above but incorporates a slight delay of about half a second or so. Or
speaking in terms of ancient turntables; it seems like someone lifts the
pickup for the fraction of a second off the record and puts it back down.

-Rainer

"Sam Goldwasser" wrote

What type of skipping is it? Short distance, long distance, or just
a repeat or dropout?

--- sam | Sci.Electronics.Repair FAQ Home Page:
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 Site Info:
http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work.
To
contact me, please use the Feedback Form at repairfaq.org. Thanks.
Click to expand...
 
Thanks for that answer,
but as I stated before not only once but TWICE; the lens has been cleaned.
And yes it uses a wormscrew, but before you jump to other conclusions; I
already removed and cleaned it and relubed it. I even took a needle and
removed dirt and particels which were stuck very down between the teeth of
the two gears connecting the wormgear to the motor. But all to no avail.

I may get a second working SL-S120 tonight and do some some comparative
measurements - maybe even swap the whole mechanics.

Rainer

"Mark D. Zacharias" <mzacharias@earthlink.net> schrieb im Newsbeitrag
news:hDslb.783$I04.708@newsread4.news.pas.earthlink.net...
Obviously clean the lens if you have not done so.
Also, recent vintage Panasonics use a wormscrew drive for the pickup. The
tolerances are tight, and the least bit of hair or carpet fiber will tend
to
jam them up. Yours could be in a borderline mech jamming condition
involving
the wormscrew (sled) drive.


Mark Z.
Click to expand...
 
To Mark
Sorry if that last reply sounded a little harsh...You were just trying to
help. I apologize.

Okay for the records...
I am pretty sure now it must be an electronic problem...

I took the mechanics from the defective player and attached it to the
electronics of a working Panasonic SL-S120 I borrowed. It workes like a
charm with a stable and sharp RF pattern of 0.9Vpp. No dropouts no skipping.
This proves that the mechanics in my player are working. The fault has to be
in the electronics of my player. I'll recheck the caps and soldering as far
as this is possible with SMD. Maybe replace the xtal on trial and error
basis, but the rest would call for a schematic or download of the LSI/driver
datasheets.

Rainer


"Mark D. Zacharias" <mzacharias@earthlink.net> schrieb im Newsbeitrag
news:hDslb.783$I04.708@newsread4.news.pas.earthlink.net...
Obviously clean the lens if you have not done so.
Also, recent vintage Panasonics use a wormscrew drive for the pickup. The
tolerances are tight, and the least bit of hair or carpet fiber will tend
to
jam them up. Yours could be in a borderline mech jamming condition
involving
the wormscrew (sled) drive.


Mark Z.



"Rainer F. Daltrop" <flintstone0183@hotmail.com> wrote in message
news:bn3b7t$scten$1@ID-210863.news.uni-berlin.de...
Hi Sam

In general it is a short distance skip as if it would jump from one
groove
to the immediate neighbor without delay. Most of the time this skip will
cause a repeat sometimes an advance. The best analogy would perhaps be
that
of an old turntable skipping on a slightly scratched record but without
going into looped repeat.
The second sort of skips is does covers the same short distance as said
above but incorporates a slight delay of about half a second or so. Or
speaking in terms of ancient turntables; it seems like someone lifts the
pickup for the fraction of a second off the record and puts it back
down.

-Rainer

"Sam Goldwasser" wrote

What type of skipping is it? Short distance, long distance, or just
a repeat or dropout?

--- sam | Sci.Electronics.Repair FAQ Home Page:
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 Site Info:
http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer
work.
To
contact me, please use the Feedback Form at repairfaq.org. Thanks.
Click to expand...
 
Hi
I guess I got the problem solved.
After replacing the 16.93MHz Xtal and resoldering the associated SMD caps
C501,502 the unit seems to work again. At least the problem of
sporadicskipping and dropouts hasn't reoccured within the last hours.
Thanks again to all who have helped.

Regards
-Rainer

"Rainer F. Daltrop" <flintstone0183@hotmail.com> schrieb im Newsbeitrag
news:b6988f2f.0310120102.6cb15aac@posting.google.com...
Hi
I am doing a charity repair of Panasonic portable CD-Player SL-S120
and need some data for realignment procedure. Poor thing came in with
all controls severely tampered; Wiper on VCC adj pot gone, alignment
screws on optical pickup were tightened, yet Laser power adj seems
untouched.
Fault found and repaired was open tracking coil; one suspension wire
at lens assy had broken free.
I managed to replace the destroyed pot and without service data
adjusted VCC (voltage after the stepup regulator) to 3.3V (wiper
slightly below midrange of VCC control range; 3V - 4V). I readjusted
the mechanical tilt of the lens to enable tracking and focus but the
Unit skips track occasionally and is very susceptive to even slightest
movements.
Could anyone look up the VCC setting on that model and enlighten me if
there is a simple way to adjust the mechanical alignment of the lens
assy? Any procedure that can be followed without special Test-Disc? If
I set mechanical alignment to produce maximum voltage of the eye
pattern (with laser power untouched) the skipping of tracks gets
better, but the unit gets more susceptive to vibrations.

Thanks
Rainer
Click to expand...
 
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