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Some CDROMs include audio tracks that are entirely playable. However, data-only CDROMs may not even be recognized by newer CD players. With older ones - designed before the CDROM standards had been developed - the player may come up with a bogus track directory. Attempting to 'play' such a disc will probably not damage the CD player but will sound, shall we say, strange. I have done this and it really gets pretty boring pretty quickly. But, like pointing the camcorder at the video monitor, is something that is irresistible to try once. If you do this experiment, TURN DOWN THE VOLUME!!!. None of the rules which govern real-world audio frequencies and amplitudes are obeyed with data discs. You may blow out your speakers (or ear drums) if the volume is set too high or even at normal listening levels. I wonder what WIN.EXE or vmunix really sounds like!
The question arises: "How do I determine if my new, newly acquired, newly repaired or adjusted, or other CD player is actually performing up to specifications?". Note that in this section I am not addressing questions like: "Is my THD less than .003% (or whatever)?" but rather general usability issues like immunity to disc defects. If the music sounds right, the audio circuits are working. Subtle problems with the audio circuitry are rare. The best approach is to use the test disc(s) that most manufacturer have made available for their own CD players. However, this is probably an unacceptable expense unless your repair volume can justify it. No single test disc will be suitable for all brands. One problem is that CD players from different manufacturers (and even models from the same manufacturer) have varying amounts of tolerance to CD defects and varying levels of error correction (by design). Therefore, what plays on one may result in dropouts or skipping on another. Without the test discs, no quantitative measurements can be made. However, general types of tests can be done. My general recommendation would be to use a good quality music CD which is a full 74 minutes (e.g., Beethoven's 9th Symphony) to test basic seek and tracking capabilities. Exercise the player with track-track and full disc seeks in both directions to confirm stability and that none of these times are excessive. Evaluate bump immunity with your calibrated finger tap at the start, middle, and end of the disc. Also see the sections: "Comments on test discs" and "Custom test CDs using CD-Rs". Want to have fun? Find a garbage CD - one you don't really care about - and add imperfections of your own to the non-label side - using it as a frisbee or hockey puck should qualify. I would also suggest smudges but these are not permanent and what we want is something that will not change over time. Maybe try some fine sandpaper or steel wool. Painting fine strips of black radially (up to a width of 2 mm or so) may also be instructive though in reality, although the error correction may be capable of dealing with these, there may still be skipping or other mistracking. As long as the CD does not have any edges for the lens to catch on (it is not cracked or broken), there is little risk to your player. Scratching through the label side to the pits (information) layer may also be intersting. In this case, the data and tracking will be affected directly since the benefits of the out-of-focus surface (the non-label side) are lost. With this 'scientifically designed test CD' you should be able to gain a feel for how your unit-under-test compares to the CD player you normally use. However, don't be too disappointed if one or the other falls down in some respect. CD players are just not all designed alike. You may find that your $100 portable doesn't even hiccup on defects that send your $1000 audiophile model (which you thought was the ultimate in the state-of-the-art) straight to the showers. Finally, if you take reasonable care of your CDs (and don't position the CD player in front of your Megablaster-1000 speaker systems, you won't be 'pushing the envelope' during normal use and your CD player will not have to deal with marginal discs and vibration that often. For more fun, see the article: "Where is CD Date Physically?".
"Is a special expensive test CD needed for typical servicing?" "Can anyone recommend a test CD disk. I want test tones more than recorded music, single note sinewaves rather than sweeps." I ordered one from MCM Electronics called the "Diagnostic Test CD" for about $5. It has over 40 tracks mostly of pure tones (sinusoids) of various pitches (frequencies) and amplitudes. However, as noted below, an appropriate test disc is more likely to be useful for evaluating tracking performance than for audio distortion problems. Any music CD will suffice for the latter - these faults are usually quite obvious even to your average chimpanzee (or someone who is tone deaf). Test discs like the following will provide nice quantitative info and should be useful in comparing the defect tolerance of various CD players. However, you will need to know what the specifications are of the player-under-test to really be able to determine if it is performing properly. (From: Dave A. Wreski (dawreski@nic.com>)). We don't think that test tones are so important in real life. The few CD players that have audio distortion problems are usually so bad it does not take a trained ear to hear. What we found much more important is the ability to track through damaged or dirty sections on the disc. Although not the, final the test disc we use has been proven to provide us with a "standard" that we judge the overall performance of the servo's and the laser condition. Very rarely do we have to ask an owner for the disc that exhibits his problem. This disk is from Technics and is about $35.00. It is P/N SZZP1054C. It has the necessary test tones (17 tracks) but more important it has defects at calibrated levels. First it has missing pits at .4 to .9 mm in length and second it has calibrated black dots from .3 to .9 mm in size. These checks will give you a very fast and reliable way of seeing how good the system is working. We could not live without it. Try it once and you will like it forever. (From: Armand (mondo@voicenet.com)). Try the "Ultimate Test CD" on Wodford music. 32 different sine waves and more. Found it at Tower Records for $6. (From: Dan Dugan (dan@dandugan.com)). My favorite test discs are put out by the National Association of Broadcasters. More expensive but comprehensive. I use #1 (there are 2) almost every day for level setting. (From: Brian Newman (b.newman@qcm.gu.edu.au)). I normally use a Sony type 4 test disc, but if you are after tones, I would recommend the test disc put out by Dennon. It has standard tones as well as left/right sweeps.
With the continuing decrease in the prices of CD-R recorders, this approach will likely become much more common. If you have access to one at work, then there is no problem - it is probably not being used for its intended purpose anyhow :-). The only caution is that since CD-Rs are not quite the same as CDs in terms of optical behavior, some adjustments may not be optimal and should be rechecked with a normal CD or test CD. (From Kenneth Aaron (kennetha@geocities.com)). I have created a test CD using a CD-R. Using a program like Cool-Edit you can create perfect waves of different frequencies and amplitudes, silence tracks, and nearly anything else. With a program like Disc-at-Once delays can be added between tracks. After you burn the CD, holes can be drilled in the disc as well. I left a 2 minute gap between adjacent tracks so I could see the spaces between tracks. Drilling holes from .2 mm to 2 mm with .2 mm increment is allright. The disc is fantastic and it was made to fit my needs.
While it is easy to vary the pitch of a turntable or tape deck by controlling motor speed, this will not work with a CD player. Spindle motor speed is only loosely related to audio pitch. CD players use Constant Linear Velocity recording, meaning rotational speed varies from inner-most track to outside track. Reading a CD is more like transferring data from a hard drive under computer control - there is extensive buffering and the instantaneous spindle speed is not the main factor that determines pitch. For this reason, wow and flutter are generally so small as to be undetectable even with audio test instruments since readout is controlled by a very stable quartz crystal master clock, not anything electromechanical. Digital audio data is read from the disc into a FIFO (First in First Out buffer). Various processing is performed including decoding and error checking/correction and it is then fed to the DACs at a constant rate (determined by a crystal). If the FIFO gets too low, the motor speeds up. If the FIFO gets too full, the motor slows down. Very simple. Change the rate that data is read and the motor follows right along (up to a point). The actual frequency of the crystal varies from design to design but a typical value is 11.29 MHz (256 times the audio sampling rate of 44.1 KHz. If may be possible to substitute a variable frequency oscillator for the crystal to provide some amount of pitch control. With care and possibly some tweaking of the PLL servo adjustments, a pitch range of +/- 6% (about 1 semitone) should be possible. Some people have apparently achieved as much as +/- 20%, but beyond this, strange things will likely happen with tracking and the anti-aliasing (analog) filter. However, a schematic is really needed - and possibly more like chip specifications - to determine if simply injecting an external oscillator signal will work.
Why anyone would seriously consider this project other than for the curiosity value is not clear, but the question does seem to pop up from time to time. If you mean audio making a CD player into a CDROM drive. Forget it. Don't waste any neural bandwidth on such considerations. While the optics and front end electronics are similar, the CD player is missing the circuitry needed to decode the CD data, CDROMs used more involved error correction, the control inputs are not there, and it is virtually impossible to obtain detailed schematics or firmware listings. And, in the end, it would be state-of-the-art 1X drive since the servo systems and motors in an audio CD player are not capable of operation at more than 1X speed. You can probably pick up a 1X CDROM drive for $10 or less. They practically come for free in cereal boxes these days (or was that 1G hard drives? Technology moves so quickly). Similar comments also apply to the nth degree with respect to converting a CD player or CDROM drive into an MPEG video device or something more exotic.
Since nearly all CDROM drives are capable of playing audio CDs, a natural question is whether it is possible to just supply power and be able to use an old 1X (or 2X or 10X) CDROM drive as a CD player without attaching it to a computer. For many types, the answer is yes. These provide some way of starting play and moving between tracks on the front panel. Usually, this is a pair of push buttons which combine play, eject, and next track functions or a volume control that can be pushed to start play and move to the next track. All these CDROM drives usually need is power to operate as audioCD players. For headphone listening, just use the front panel jack. A suitable adapter will permit the line outputs in the rear to be connected to the CD or AUX inputs of your stereo system. Some will automatically play CDs upon powering up or closing the drawer if a jumper is set properly. The Eject button will then control play, track selection, stopping, ejecting, depending on how long it is held down. Where the drive does not have these features, this may be more difficult. * It is probably not worth it for SCSI or IDE drives as special commands will need to be set up. * I don't know how difficult it is with the custom interfaces like Sony and Mitsumi. These may have a simpler command set but I doubt that it is just jumpering a signal to ground somewhere. * For the once popular Panasonic CDROM drives with the custom interface (e.g., CR562, CR563), the interface specifications are available at: - http://www.marketto.demon.co.uk/electronics/panasoniccd.html. Some logic will likely be needed to allow the drive to play music CDs but it should not be that complex. Note that the audio performance of CDROM drives is usually a notch below that of the typical audio-only CD player. The audio circuits are basically an afterthought for a CDROM drive. Therefore, don't expect quite the same level of frequency response, dynamic range, and lack of noise as your are used to with your stereo system or even your portable CD player. Of course, in a Jeep, this may not matter much. In addition, the bump immunity is probably not spectacular - PCs are usually not expected to deal with pot holes. Therefore, unacceptable rates of skipping and repeating may result if a converted CDROM drive is used in your car or back pack. However, some people claim to have used retired CDROM drives in vehicles with great success (see below). Therefore, it is worth a try if your model doesn't require a PC to be dragged along to play music CDs! (From: Dougie (blair@irnbru.enet.dec.com)). I use a 2X CDROM Drive in my car and have done so since a local shop sold off all their drives for a fiver each!! I used a 5 volt regulator to make an in-line adapter to give me 12 and 5 volts to run the drive. You don't need any front panel controls since the eject button is used on most drives as FF/skip button. As far as bouncing and skipping is concerned. I originally put the drive inside my glove compartment and it jumped like crazy. But I now have it on the passenger's side floor under the seat and I can't remember the last time it jumped. You'll find a good spot in your car that works best. I've even thought of putting on one of these flexible goose neck platforms that are used for portable cd players, but since it works fine where it is I haven't bothered. I'm always interested in what other 'experts' tell you about the differences in internal electronics between PC CDROM drives and in-car CD players, but I work in a lab and spend every day carrying out failure analysis on CDROM drives of all types and I've always had the opinion that the only way to find something out for certain is to try it your self.... I have collected 6 of these drives now and am in the process of making them into a multi-CD player to be housed in my boot/trunk. All CDs will run continuously and only the audio will be selected and digitally switched. It should be fun and cheap.
(From: Arny Kruger" (arnyk@flash.net)). SP/DIF is common on most newer ATAPI CD and DVD drives, and specifically very rare on SCSI drives. Toshiba, Teac, Panasonic, etc, have SP/DIF. I think the long term idea is to eventually drop the headphone output and DAC in the CDROM and route SP/DIF to the sound card which will, or is being put on the motherboard. I have a number of new motherboards with SP/DIF inputs but I have not yet tested them in this mode. I know that the digital performance of the sound chip used on these particular boards (the HT1869) is horrible. Hopefully, somebody will do it 'right', as this is technology with promise. I've tested some CDROM's SP/DIF output with external audio DACs and good quality sound cards with digital inputs and they work, pure and simple. The performance of a $80 CD ROM and a $200-300 DAC (specifically the Technics SH-AC-300) can eclipse more expensive equipment, in technical terms.
With the nice precision optics, electromechanical actuators, laser diode, and photodiode array present in the mass produced pickup of a CD player, CDROM drive, or other optical disc/k drive, one would think that alternative uses could be found for this assembly after it has served for many years performing its intended functions - or perhaps, much earlier, depending on your relative priorities :-). People sometimes ask about using the focused laser beam for for scanning or interferometry. This requires among other things convincing the logic in the CD player or CDROM drive to turn the laser on and leave it on despite the possible inability to focus, track, or read data. The alternative is to remove the optical pickup entirely and drive it externally. If you keep the pickup installed in the CD player (or other equipment), what you want to do isn't going to be easy since the microcontroller will probably abort operation and turn off the laser based on a failure of the focus as well as inability to return valid data after some period of time. However, you may be able to cheat: * If the unit has a 'Test Mode', it may be possible to force the laser to remain on despite a total lack of return signal - or even without the focus and tracking actuators even being connected, for that matter. Many models have a Test switch, jumper, or pair of solder pads on the mainboard (enable before powering up). Then, there may be a key sequence to enable the laser, move the sled, etc. See, for example, the section: "Pioneer PD/M series test mode". Where such a feature is not provided: * First, whatever is used to detect a disc must be defeated. Usually, this is a reflection of the laser (most common)) but may be a separate sensor. * Then, the 'focus ok' signal must be provided even if you are not attempting to focus the laser beam. It may be possible to tie this signal to the appropriate logic level to do this. * Even if it is not possible to access these signals, depending on design, you may be able to locate the logic signal to turn on the laser and enable it there. However, some systems bury this inside a chip based on the controller to activate it. Getting a schematic will probably be essential - but this may be difficult (especially for a CDROM). It may be easier to just remove the pickup entirely and drive it directly. Of course you need to provide a proper laser diode power supply to avoid damaging it. See Sam's Laser FAQ for details. You will then have to provide the focus and/or tracking servo front-end electronics (if you need to process their signals or drive their actuators) but these should not be that complex. CAUTION: Take care around the lens since the laser will be on even when there is no disc in place and its beam is essentially invisible. See the section: "SAFETY". Some people have used intact CD player, CDROM, and other optical disc/k drive pickup assemblies to construct short range interferometers. While they have had some success, the 'instruments' constructed in this manner have proven to be noisy and finicky. I suspect this is due more to the construction of the optical block which doesn't usually take great care in suppressing stray and unwanted reflections (which may not matter that much for the original optical pickup application but can be very significant for interferometry) rather than a fundamental limitation with the coherence length or other properties of the diode laser light source itself as is generally assumed. In any case, some of the components from the optical block of that dead CD player may be useful even if you will be substituting a nice HeNe laser for the original laser diode in your experiments. Although optimized for the IR wavelength (generally 780 nm), parts like lenses, diffraction grating (if present and should you need it), and the photodiode array, will work fine for visible light. However, the mirrors and beam splitter (if present) may not be much better than pieces of clear glass! Unfortunately, everything in a modern pickup is quite small and may be a bit a challenge to extract from the optical block should this be required since they are usually glued in place.
Fortunately, the standard for the CDs themselves is the same everywhere in the explored universe. Yes, even Australia :-). Thus, there should be no issues of incompatibility. The differences will relate only to the power supply needed for your player. First, check your user's manual (which you of course have saved in a known location, right?). It may provide specific instructions and/or restrictions. Most component type CD players use a simple power supply - a power transformer followed by rectification, filter capacitors, and linear regulators. These will usually only require a small step up or step down transformer to operate on a different voltage. Since power requirements are minimal, even a 50 VA transformers should be fine. WARNING: never attempt to use one of those cheap lightweight power adapters that are not true transformers to go from 220 V to 110 V as they are designed only for heating appliances. They will smoke your CD player (or other equipment not designed to handle 220 V to 240 V input). Some CD players may have dual voltage power transformers which can be easily rewired for the required voltage change or may even have a selector switch on the rear panel or internally. The frequency difference - 50 or 60 Hz should not be a problem as nothing in a CD player uses this as a timing reference. The only slight concern would be using a CD player specified for 60 Hz on 50 Hz power - the transformer core may saturate and overheat - possibly blowing the internal fuse. However, I believe this to be a rather remote possibility. For portable CD players, if your wall adapter does not have a voltage selector switch, obtain one that is rated for your local line voltage or use a suitable transformer with the one you have. As with power transformers, a frequency difference may cause a problem but this is not likely.
This applies to the D33 - don't know about other Sonys. At least only a single jumper is involved. On the D88, it was necessary to both remove one jumper and add another. After several of these cycles, the circuit board tracks started to disintegrate :-( How about pads for a microswitch which would be part of the standard Sony service kit? (From: Jxrn-E. Ernes (joern-ea@online.no)). Remove the power supply (batteries or whatever you have) and the bottom cover. Now make a soldered interconnection between the two jumper TEST terminals and apply power again). Pressing the PLAY button should cause the spindle to spin continuously. That would make it easier to determine whether the motor is OK or not.
The following questions and comments may give you a better feel for the
considerations on attempting to repair a portable CD player (or CDROM drive
for that matter).
"I've read the relevant sections in the FAQ already. My problem concerns a
Sony D-99 discman, it started skipping, etc., but within a matter of days
degenerated to the point that it won't even read the TOC any more and is
essentially dead. All the motors work fine.
I'm assuming that the problem has to be something to do with the laser
optical subsystem or its setup. The fact that it sort of worked for a
while but rapidly degenerated suggested nothing has died totally but
something has a terminal disease. I'm guessing either that the calibration
has drifted to (and now beyond) the limits it can accept, or that the laser's
power output is deteriorating.
1. Do lasers age significantly assuming they aren't abused as noted in the
FAQ (i.e. turn into DEDS)?"
They really should not 'wear out'. Certainly not in the span of a few days
after having been faithful servants for several years. The quoted life of
a typical laser diode is 5,000 to 10,000 hours. But that assumes proper drive
There is no way of knowing for sure. FWIW, there is a disc player that I
repaired for a mechanical problem that is used something like 8 to 10 hours
a day, 6 days a week for the last 5 years or so. It is still going strong.
"2. Since it is a small Discman, I worry a little that it will either go
'pling' when I take the back off (not that that ever stopped me opening
things before) but more seriously there will be little I can do when I
get in there."
Portable CD players tend to be fairly well behaved when the covers are removed.
However, I am not optimistic about your chances of repair. Some careful
exploration should not harm anything (not that it is likely to matter). I
have found from my experience with portables that working on those things
is a pain. This is especially true of older Sonys where the mainboard is
connected to the optical pickup with many fine soldered wires in addition to
soldered in flexible cables.
"3. Sony have *not* been helpful. They will likely charge me the same as it
costs to buy a new one, which is a shame because this old girl is actually
made of metal and I hate the horrid plastic feel of the new toys, even
if the batteries last longer and it sounds as good. The Sony man himself
said that the new ones are built down to a lower price."
Forget Sony. If I interpret the model correctly, that one is fairly old. You
would be lucky to get their attention for something 1 day out of warranty.
"4. Should I pay the man?"
The temptation of some repair places is to blame the optics without even doing
any testing - which alone will set you back more than the price of a new basic
player (well, it will do everything yours will do but weigh half as much!).
"5. Should I throw it away?"
That would be a shame but it depends on how much you value your time versus the
cost of a new one. I really do respect the look and feel of those old Sonys.
Needing to reseat internal connectors, dirty controls, mechanical problems,
are still possibilities.
Also, if you are using an AC adapter, make sure *it* is not the one that is
terminal!
However, adjustments may not even be marked and if it is now totally
unresponsive, there is no way to really tweak them without a service
manual.
"6. Should I take the back off, nothing to loose, then most likely throw it
away?"
First, clean the lens and check the mechanics, and the AC adapter.
Next, see the chapter: "Startup Problems".
Then try to identify how far it is getting. This can probably be done without
taking the back off.
You can pretty much forget attempting to repair the circuitry - most components
are surface mount - both very tiny discrete parts and large multilegged ICs.
It is difficult to obtain data sheets for many of these. The service manual
is not always complete enough to be much help. Even probing test points
without shorting anything out or having the whole mess fall on the floor
while balancing the guts of the player and pushing buttons typically requires
a minimum of 4 hands.
"7. Do I stand a chance to find someone who will give me a better likelihood
of success at a reasonable price than the local sony man (who to be honest
looks like his idea of repair is to replace it in any case, certainly on a
module level)?"
IMO, unlikely. It takes more time to get into one of those than a full size.
Time is money. Etc. They would probably have to order the manual which is
an added expense that may never be useful for a future customer.
"Sorry if "throw it away" isn't in the spirit of things, but hey."
Sometimes it is.
"P.S., one improvement to the FAQ would be to outline the likelihood that
things actually have worn/died with age, rather than simply how to adjust
or repair something that just doesn't work for some reason. This one has
had a lot of use over five years."
Unfortunately, aside from things like grease gumming up or mechanical parts
collecting dirt, optics getting coated with dust, tobacco smoke or cooking
grease residue, motor bearings wearing out, the electronics and optics really
should not age. Of course, there are all kinds of ways that this could
happen through use and abuse (e.g., large dogs, toilets, and salt air) or
bad design.
Although a CD player mounted in an automobile or ATV is subject to much greater levels of vibration and shock than a home stereo (though perhaps not more than a well used portable), this may not be the primary factor affecting the long term survival of these devices. Other considerations are cycles of heat, cold, and humidity; dust and tobacco smoke; and the harsh environment of the vehicle's electrical system. Temperatures under the dash or in the trunk can easily vary from below 0 F to more than 110 F during the year. Humid and salt air are particularly nasty. The confines of the passenger compartment concentrate tobacco smoke products so the lens and optics may suffer more in this environment. "I have recently install a Panasonic in-dash Cd, My problem is the cd player does read and play but it will stop suddenly and eject itself, few of my friends have told me it could be due to dirty lens and I have seek a second opinion from a pro car audio installer and they told me is my lens are damage and need repair." (From: Filip M. Gieszczykiewicz (filipg@repairfaq.org)). If you installed a *new* player, I doubt that this is the problem. Most likely, alas, is a wiring mistake or a bad connection. Did you follow the instructions and use the recommended wire harness adapter? Did you provide a good, solid ground? What wire-splicing method did you use? Did you tape/heat- shrink all connections? Did you mount the radio securely in the dash? Most car CD-players will spit out the disk when power is interrupted to them. Does it happen when you hit a bump or are going over rough road? Check over the wiring, then check the ground, but first check *when* exactly the problem appears! Take it for a test-drive over a bumpy road: does the light flicker before the disk comes out? Any noise from the speakers?
The average person thinks that a CD player or CDROM drive is a delicate piece of precision equipment that will die given the least excuse. Well, chalk at least one up for the good guys! (From: Joseph E. Fealkovich (jef812@ix.netcom.com)). My best friend calls me up, he works at a computer outlet in Cleveland, OH (figure it had to be Cleveland :-) --- sam), to tell me he has a Teac CDROM he 'accidentally' ran over with a pallet truck loaded with about 850 pounds of DOS and Windows (who says software isn't a tangible asset :-) --- sam). The CDROM drive is crushed a little bit in the rear, the faceplate popped off and skittered across the floor. Upon obtaining this CDROM drive, I look at it and yes, the back part is pretty well damaged. Me and my good friend Timmy take this poor unit apart to look at the insides. I'll be damned, there is no internal damage whatsoever. All that has to be done is straighten the main chassis of this CDROM and straighten out the outer case. While I was at work straightening out the CDROM, I hit Teac's website to get the drivers for this CDROM, and I'll be double damned, IT IS A 16X CDROM DRIVE!! COOL! The model number is CD-516E, cool, if I get this gem working, I can put it on my secondary port on my 32-Bit IDE interface. Sure enough, I straightened out the crushed case on this unit and I install it with the drivers I downloaded from Teac's website. This CDROM works like it was brand new!:-) WOW, is this damn thing fast! COOL, I got a free 16X CDROM, all I had to do is fix the damaged case and chassis!:)
This is right up there with $400 hammers and $20,000 toilet seats :-) MCM Catalog #38, page 500: Original Aiwa/Sony Spindle Assembly: $94.50(ea). It is part number 32-7275 if you are eager to order one ;-). From the picture, this is the type of spindle assembly used in the typical $70 portable CD player or cheap (by now obsolete) CDROM drive - a $1.99 Mabuchi style motor (two pin connector included!) and plastic self locking spindle platter glued or pressed to the shaft. Do people actual pay this???? Why would anyone spend almost $100 for one of these replacements? Yes, I know most of the answers. The question is to stimulate discussion.
There seems to be some debate as to what extent weak suspension contribute to uncorrectable (by the internal adjustments) skipping and other erratic behavior. However, it is generally agreed among those who actually have to repair CD players and CDROM drives using Sony KSS pickups that such deteriorated suspensions can indeed be a cause of a variety of problems. (From Mark Z. (zmachar780@aol.com)). Anyone who has worked much with these units knows that the suspension can be a factor, especially where a player is somewhat finicky about which discs it likes or doesn't. This is particularly true of the D- series portables. I call attention also to the Denon DN2000 type dual players which use the KSS240A optic. Replacing the pickup seems to *always* fix these type of erratic skipping problems. There is no way I know of to tell for sure that the focus bias or other adjustment won't get it back into nominal area of operation, other than just trying it. In fact, adjusting the focus bias (focus offset) is often done to get the player into a better operating area, and to save the expense of a new optic. With a player say, 4 to 5 years old, the actual deterioration may be quite minor, and the adjustment may be all that is needed. Of course, if if it is really that minor, why was it acting up in the first place? I disagree with Sony on the issue of deterioration. I've seen too many examples, particularly when the objective lens is 'bottomed out'. If the focus servo is really able to overcome this physical problem: * The focus drive electronics, transistors, IC, whatever will run unnecessarily hot. These circuits are designed to have a zero average offset to lower average power dissipation. * Why then does the RF signal look so bad on players where the disc table is installed at the wrong height by as little as 1/2 mm? However, most skipping, sticking, repeating, and similar symptoms are still caused by feed problems and spindle motors. Sony is correct to state that many pickups get replaced unnecessarily. I attribute this to inadequate technician training, and also that CD players work by FM.... (F***ing Magic). tech humor. Ha. Ha :-).Go to [Next] segment
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