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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Panasonic CD-Player SL-S120 help with realignment
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 |
#3
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Panasonic CD-Player SL-S120 help with realignment
(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. 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/ +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. |
#4
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Panasonic CD-Player SL-S120 help with realignment
Hi Sam
Thanks for your answer... Does reducing VCC to say 3 V make any difference? 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. 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? 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? 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 |
#5
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Panasonic CD-Player SL-S120 help with realignment
Hi Sam
Thanks for your answer... Does reducing VCC to say 3 V make any difference? 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. 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? 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? 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 |
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Panasonic CD-Player SL-S120 help with realignment
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. |
#7
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Panasonic CD-Player SL-S120 help with realignment
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. (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. |
#8
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Panasonic CD-Player SL-S120 help with realignment
"Sam Goldwasser" 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. 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 |
#9
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Panasonic CD-Player SL-S120 help with realignment
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. |
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Panasonic CD-Player SL-S120 help with realignment
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. |
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Panasonic CD-Player SL-S120 help with realignment
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. |
#12
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Panasonic CD-Player SL-S120 help with realignment
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" wrote in message ... 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. |
#13
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Panasonic CD-Player SL-S120 help with realignment
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" schrieb im Newsbeitrag k.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. |
#14
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Panasonic CD-Player SL-S120 help with realignment
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" schrieb im Newsbeitrag k.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" wrote in message ... 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. |
#15
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Panasonic CD-Player SL-S120 help with realignment
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" schrieb im Newsbeitrag om... 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 |
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