Contents:
If your player uses a brushless DC motor for the spindle then you may not be able to perform any electrical tests as the commutation control may be external on the circuit board somewhere. These do not fail very often, either. An open or shorted winding may result in a 'bad spot' - a position at which the motor may get stuck. Rotate the motor by hand a quarter turn and try it again. If it runs now either for a fraction of a turn or behaves normally, then replacement will probably be needed since it will get stuck at the same point at some point in the future. Check it with an ohmmeter. Also check between each terminal and the case - the reading should be high, greater than 1M ohm. A low reading indicates a short. The motor may still work when removed from the equipment but depending on what the case is connected to, may result in overheating, loss of power, or damage to the driving circuits when mounted (and connected) to the chassis. Clip the ohmmeter leads to the motor terminals and rotate the shaft extremely slowly. The motor will act as a generator as your spin it resulting in the resistance readings increasing or decreasing depending on direction. However, the readings should stabilize once you stop. The resistance should be fairly constant as the shaft is rotated with periodic dips where pairs of commutator segments are shorted by the brushes. The number of cycles per revolution is determined by the number of commutator segments used (most use only 3). Any extremely low reading may indicate a shorted winding. An unusually high reading may indicate an open winding or dirty commutator. Cleaning may help a motor with an open or short or dead spot as noted below. Typical resistance of these motors will be 10 to 25 ohms (though I have seen some apparently good motors reading as low as 5 ohms), fairly constant as one rotates the shaft except for dips at 3 points where the brushes short out each pair of commutator segments (there are generally 3 segments on these motors). A motor can be tested for basic functionality by disconnecting it from the circuit board and powering it from a couple of 1.5 volt alkaline cells in series (3 V) or other power supply up to 9 V or so. WARNING: Never attempt to power a motor with an external battery or power supply when the motor is attached to the circuit board - you may blow electronic components on the circuit board and complicate your problems. Disconnect *both* terminals and label the wires or motor orientation so you can reconnect it with the proper polarity. If you use a variable power supply, the motor will start spinning slowing at less than a volt and continue without tending to stop at some point in its rotation. Using your fingers to monitor the torque produced as it rotates can also provide an indication of its health. It should be fairly uniform with slight periodic dips due to the commutator construction and number of segments. It is also possible to confirm that the electronics are attempting to drive the motor by substituting a 15 or 20 ohm 1 W resistor for the motor. The driver circuit should develop a few volts across this load when it is supposed to be active. If there is no voltage at any time, then the driver may be blown or not have power, or the logic is not instructing the motor to spin!
Dirt or grime on the commutator can result in intermittent contact and erratic operation. Carbon or metal particle buildup can partially short the motor making it impossible for the controller to provide enough voltage to maintain desired speed. Sometimes, a quick squirt of degreaser through the ventilation holes at the connection end will blow out the shorting material. Too much will ruin the motor, but it would need replacement otherwise anyway. This has worked on Pioneer PDM series spindle motors. I have heard of people using carburetor cleaner successfully but I would recommend something a little less harsh to start. Contact, circuit board, or tape head cleaner may work. Another technique is to disconnect the motor completely from the electronics and power it for a few seconds in each direction from a 9 V or so DC source. This may blow out the crud. The long term reliability of both of these approaches is unknown. WARNING: Never attempt to power a motor with an external battery or power supply when the motor is attached to the circuit board - you may blow electronic components on the circuit board and complicate your problems. Disconnect *both* terminals and label the wires or motor orientation so you can reconnect it with the proper polarity. It is sometimes possible to disassemble the motor and clean it more thoroughly but this is a painstaking task best avoided if possible. If you do manage to revive it, also see the section: "Spindle motor drive modification to minimize chances of future problems".
The spindle motor should be replaced with an identical unit though it doesn't have to be the exact manufacturer's part number - universal substitutes are often available at a much lower price. However, there may be alternatives for other types. Most of the other small PM motors found in CD players and CDROM drives (as well as VCRs and other consumer electronics and small appliances) are basically pretty similar. The important differences are mainly mechanical - size, mounting, shaft length, etc. There may be variations in nominal voltage and current usage but for non-critical applications like drawer loading or disc changing, if you can make a generic replacement fit the space and attach to the drive components, There is a good chance that it will work well enough. Such replacements may be available from companies like those listed in the section: "Recommended parts suppliers". Check a few catalogs!
A dry or worn bearing can make the motor too difficult to turn properly or introduce unacceptable wobble (runout) into the shaft as it rotates. Feel and listen for a dry bearing: The shaft may be difficult to turn or it may turn with uneven torque. A motor with a worn or dry bearing may make a spine tingling high pitched sound when it is turning under power. A drop of light machine oil (e.g. electric motor oil) may cure a dry noisy bearing - at least temporarily. For spindle motors (these are the only motors in CD players where runout is critical), try wiggling the shaft from side-to-side - any detectable movement is an indication of runout. At some point, this will be bad enough such that the focus and tracking servos will be unable to compensate for the runout and audio noise and skipping may result. Some oil may help but a spindle motor with a worn bearing will require replacement eventually. Furthermore, it may prove impossible to reach the bearing(s) to lubricate them properly. See the section: "Spindle motor problems" for more information.
The following are some indications that the spindle motor may be defective or need attention. However, insufficient spindle motor voltage or current could also be due to spindle motor driver faults, incorrect power supply voltages, or logic problems. Note: If the disc doesn't spin at all, try rotating it by hand while it is trying (or with the servos enabled if it has a TEST mode). If you hear that 'gritty' sound, the focus and probably tracking servos are working but the spindle motor or driver are faulty. * Focus is successful but disc does not spin (dead motor or dead spot on motor, shorted motor, bad connection). * Disc spins but at too slow a rate or is erratic or needs some help (weak motor or dead spot). Reading of disc directory may be erratic. (Try helping motor out by hand). * Voltage across spindle motor is only 1 V or less while attempting to spinup and read the directory and climbs to 5 V or more with the motor disconnected (partially shorted motor). * Spindle bearing runout is excessive (i.e., detectable by wiggling the spindle from side to side) or spindle motor bearing is dry or tight (try lubricating if possible). * Repetitive noise or dropouts at the disc rotation frequency or twice the disc rotation frequency. This may get worse toward the end or outer tracks of the disc. (Excessive spindle bearing runout or bad windings). Check the motor before replacement (see the section: "Small motors in CD players" for general motor problems and testing). You should be able to easily confirm or eliminate the spindle motor as the cause of your problems. If either of the cleaning or rejuvenation techniques make a significant difference in performance, then the motor is almost certainly at fault. If the player now functions normally - leave it alone or, perhaps, try the circuit modifications suggested in the section: "Spindle motor drive modification to minimize chances of future problems". The spindle motor is often blamed for everything from long distance skipping (coarse tracking problem) to disc spinning too fast or in wrong direction (a control problem). Spindle motors do fail but they are not at the root of all problems.
This suggestion is directed toward Pioneer players of the PD and PDM series with known common spindle motor problems. It may apply to other Pioneer models and other brands as well. It can be used whether you have just rejuventated an existing motor or installed a replacement. For Pioneer players, there is actually a circuit modification to reduce the possibility of repeat problems but it requires changes to the wiring - cuts and jumpers - which I prefer to avoid. My recommendation is to try the following which can usually be added at the motor terminals. (I have not done this yet, so no guarantees): Put a series string of 4 1N400X diodes in parallel with another similar string in the opposite direction across the motor terminals. This will limit the maximum voltage to about 3 V instead of the 6 V or more that it is now. The reduced voltage should reduce chance of damage to the commutator at spin-up. On the Pioneers at least, the motor driver should not mind the extra load during any peaks where the diodes kick in. It may take a couple seconds extra to start up but I believe it will still work fine otherwise. If you do this, let me know how it works.
Mark the height of the old spindle platter before you attempt to remove it. The best approach is to make a shim that will fit between the bottom of the spindle platter and the motor as a stop. The height is usually specified to a precision of 1/10 of a mm. Too low or too high and the disc may rub. This is probably overhill - 1/2 mm is probably good enough but try to get it as close as possible. The focus servo offset adjustment will make up for any height error in so far as focus is concerned. The spindle is often press fit and difficult to remove without damage. It is critical that when the spindle is replaced, it be mounted perfectly with no wobble. If you can obtain a new spindle platter with the new motor, this is the best option. If not, take every precaution to prevent damage to the spindle platter during removal - even it it means destroying the old motor in the process. See the section: "Spindle platform pulling". When press fitting the new spindle, the use of an arbor press or drill press is highly recommended. Put a block of wood under the bottom of the motor and your previously made shim between the spindle platter and the motor. Press straight down - slowly and firmly. Err on the side of being to high and check the height. Repeat until you get it perfect. It is much easier to press a little more than to raise the height if you should go to far. If there is a set screw, your job is much easier. Other mounting schemes may be employed - use your judgement in replacement procedure. For non-press fit installations, a drop of loctite or nail polish will reduce the chance of it working loose.
What was your excuse for not marking it? Oh, an elephant sat on the player and that is why the motor needed replacing but the height was already messed up :-). If the player operates normally after spindle motor replacement, as they say "If it works, use it". I wouldn't worry about it. The focus servo has a wide range. If you are curious, try to locate the test point for focus error. It should probably be a noisy waveform centered around zero volts. However, this may not be the case and you would need the service manual to be sure of what it should be. As long as the player seems to locate the disc directory quickly and plays normally, leave it alone! However, if it now has problems either taking a long time to start play or exhibiting unusual noise or skipping during play, you should probably try to obtain the spindle platter height specification and set it more accurately. I definitely would not recommend mucking with the spindle platter height unnecessarily if it is a press-fit. You would probably end up with a bent shaft and need for yet another replacement motor. However, if the spindle platform is secured with a set screw, you can try to adjust it to minimize focus error and/or optimize playback performance.
I was able to remove the spindle platform on a Philips CD pickup using the lawn mower engine flywheel pulling approach - levers under both sides of the platform so the pressure is upwards and not sideways while tapping on the center of the shaft with a thin punch. Thus, there was no shaft bending. I believe that the motor survived without damage. I was actually going to 'machine' a mini-flywheel puller but then I said: "What the heck, that is too much work :-)" In any case, the spindle platform is completely undamaged and the motor could probably be reused. However, be careful what you are prying against - the mounting may use tiny screws into plastic or something equally fragile. Of course, if you plan on doing any serious hammering, remove all the delicate optical and electronic components first!
This assumes the bearings are in good condition but the shaft has somehow gotten slightly bent. You might ask: How could this happen? Once cause could be using an improper technique to remove or attempt to remove or install the spindle platform from/to the motor shaft or something heavy falling on the player. Right, I know; in this case, a bent shaft will likely be the least of your problems! :-) (From: Filip M. Gieszczykiewicz (filipg@repairfaq.org)). I use something as simple as a pencil. Start the motor going and put the pencil right above - but not touching - the part that is bent. Now move it in tiny increments towards the bent part. When you hear the first tiny "scrape", stop the motor and note where the pencil mark appears. This is the place you want to press down to even it out. This is loads of fun with a CD spindle motor and sometimes it's just easier to get a replacement. Trust me.
The following applies to sled positioners using conventional permanent magnet motors with the typical gear or screw mechanism. (Those using linear motors use closed loop servo systems with a drive coil and sense coil. About all you can do to test these without a schematic is to check for continuity of the two coils.) Sled motors tend to be less likely to fail than spindle motors but can suffer from similar afflictions. The following are some indications that the spindle motor may be defective or need attention. However, insufficient sled motor voltage or current could also be due to sled motor driver faults, incorrect power supply voltages, or logic problems. These problems could also be of an erratic nature if the motor has a dead spot or is partially shorted. The sled motor (or its driver and associated circuitry) may be at fault if: * The sled fails to reset to the inner track. * Focus is established and the disc begins spinning at the proper speed for the current pickup location but the pickup fails to move to the selected track location. * There are problems with discs repeating more-or-less the same musical segment every few seconds (the sled gets stuck) or long distance skipping (the sled sticks but then once enough of a fine tracking error develops, breaks free and overshoots the proper location). The motor may have a dead or weak spot in its rotation. Rotate it by hand 1/4 turn or so and see if it now spinds normally or a fraction of a turn. See the section: "Testing of motors". Of course, any of these could also be due to mechanical problems as well so eliminate these as possibilities first.
The sled motor may actually receive its drive from two sources (maybe more)
as shown conceptually in the diagram below. These may or may not be separate
physical outputs tied together:
Slew+ o--------+
|\ |
Tref+ o------|+ \ |
| >------------+ |
+--|- / | | |\ Sled Drive
| |/ TE+ Comp | +----|+ \
| +----------|+ \
Tracking Error o---+ | >--------o + Sled
| +----------|- / +---o - Motor
| |\ TE- Comp | +----|- / _|_
+--|+ \ | | |/ -
| >------------+ |
TRef- o------|- / |
|/ |
Slew- o--------+
1. Slew driver - this is used when the pickup is resetting or moving across
the disc. The motor is commanded to move smoothly in either direction
or is searching for the general vicinity of the starting location (time
code).
Where the pickup is unable to reset to the inner track or unable to move
to an outer track during seek operations, a part of this driver or its
associated circuitry may be at fault.
3. Coarse tracking driver - this is used to move the sled a small amount
during play to recenter the pickup once the fine tracking error exceeds
a threshold. Many designs will do away with explicit comparators (as
shown above) and just use the friction of the sled motor/mechanics to
result in movement once the voltage on the motor becomes large enough.
This would seem to waste power, however, and be undesirable for battery
operated portables, at least.
Where the seek operation completes normally and the music starts playing
but then gets stuck or jumps back and repeats after a few seconds, the
coarse tracking driver or its associated circuitry may be at fault.
Any of these symptoms may also be caused by a defective sled motor or
mechanical problems - probably more likely than bad electronics.
(Refer to the photo of the Pioneer CD Player Optical Deck for parts identification.) Where a Pioneer player or changer does not recognize discs, the most common causes are: 1. Partially shorted spindle motor due to 'crud' on commutator. Cleaning may be possible. Generally, disc will spin but at insufficient speed. Try TEST MODE toward latter (outer) part of disc as the required rotation rate is lower and/or check voltage to motor, below. See the section: "Reviving a partially shorted or erratic PM motor". 2. Cracks in flex cable to optical pickup assembly - replacement of flex cable will be required. This may also result in erratic operation while playing. The Pioneer replacement part number for the improved version of one common cable is PNP-1343 but confirm this is correct for your model before you order. Sometimes, the flex cable is just not positioned properly (clear of the metal cover) and just needs to be 'adjusted'. 3. Collapsed rubber suspension grommets. There may be a scraping or clicking sound associated with this failure. For changers, gently lift up on the optical pickup assembly while the disc is attempting to spin to see if the disc is recognized and will play. Replace the deteriorated grommets. For general information, see the sections starting with: "Startup sequence".
The TEST mode available on some CD players is extremely useful for narrowing
down problems. The following are for the Pioneer PD/M series of CD players
and changers:
* To enter TEST mode, press the TEST button while turning POWER ON and then
hold it on for at least 1 second.
- Some models only have a set of contacts - Pioneer saved 2 cents on a
switch! Short between these with a piece of wire or a paper clip instead
of pushing the button.
- On players with a standby mode (not a hard on/off switch), plug the unit
in while pressing the TEST button or shorting the contacts.
The TEST button or contacts are located on the main board (usually near the
front right corner - may be obscured by cables).
Once TEST mode is engaged, the servos can be controlled from the front panel:
* STOP turns all servos OFF.
* TRACK FWD (>>|) enables FOCUS servo (and loads disc 1 in changer).
* PLAY enables SPINDLE servo.
* PAUSE enables TRACKING servo.
* MANUAL SEARCH FWD (>>) or REV (<<) to move the optical pickup.
Depending on model, the specific functions and behavior of the front panel
buttons in TEST mode may vary slightly.
WARNING: Normal safety checks are disabled in TEST mode. Thus, the laser may
remain on as long as focus/tracking/spindle servos are engaged even if no disc
is in place. Take care.
Power cycle (by unplugging if necessary) to return to normal mode.
Here are the typical measurements for the PD/M series players: * Spinup: >2.5 v. * Time to lock (est): 1-2 sec. * Start of disc (500 rpm): 1.0 v. * End of disc (200 rpm): .5 v.
When bad, spindle servo drive tops out at .6 V and 100 ma. Player is unable to spin up to required 500 rpm to read disc directory. While exact cause is unclear, theory is that large voltage applied at startup followed by long periods of very low voltage (.5-2 V) operation allows conductive crud (carbon) to build up on commutator eventually reducing resistance to the point where the driver cannot apply enough voltage to achieve 500 rpm. A short squirt of degreaser through motor access hole had an immediate dramatic effect returning operation to normal. It is not known how long this will last. (Also see the alternative procedure in section: "Reviving a partially shorted or erratic PM motor".) Collateral symptom: Spindle motor servo drive IC becomes quite warm when attempting to power shorted motor. However, it does not appear to be harmed. Use TEST mode to play disc at outer track. If this is normal, then spindle motor is probably bad as the rotation speed at the outer tracks is less (200 rpm) and a partially shorted motor may still run fast enough for this.
The following procedure assumes that unit is functional but internal
controls may have been moved from their correct position. This procedure
has been determined experimentally and is subject to change without notice.
If you have not touched the internal controls, there is no need to perform
this procedure. Use techniques and observations discussed elsewhere in this
document.
A number of Pioneer CD players have used very similar designs. However,
technology sometimes the implementation changes dramatically between units
with virtually identical model numbers. It is known that this adjustment
procedure applies to many older Pioneer single disc players (e.g., PD5100)
and magazine changers (e.g., PDM400/500/600 etc,). However, newer models
that appear virtually identical to these may require a totally different
adjustment procedure. Therefore, use at your own risk! With minor (and
obvious) modifications, this general approach should also apply to many CD
players from various other manufacturers as well.
I also recommend you read the section: "General servo adjustment procedure"
in its entirety before proceeding to tweak your Pioneer player.
Assumptions:
* Controls on the main board have been moved or are in an unknown state but
not on the flex-cable or optical pickup assembly.
* The player is otherwise functional - no physical damage.
And now for the fun:
1. Set all the main board controls to their midpoint.
2. Power up the unit in TEST MODE (hold down the TEST button while
powering on.
3. Adjust TR.BAL (Tracking Balance) to the center of the range over which
the sled remains stationary. Outside this range, the pickup will slew
to one end or the other.
4. While monitoring TP1-6 (FO.ER, Focus Error) with a VOM or DVM, adjust
FO.OFS (Focus Offset) for a reading of 0V +/- 10 MV. Note: I have
found that on some players, this may not actually be quite optimal
and fine adjustment be beneficial.
5. While monitoring TP1-2 (TR.ER, Focus Error) with a VOM or DVM, adjust
TR.OFS (Tracking Offset) for a reading of 0V +/- 10 MV. Note: I have
found that on some players, this may not actually be quite optimal
and fine adjustment be beneficial.
6. Load a magazine with a disc in slot 1 and press >>|, TRACK SEARCH Forward.
This should load the disc and enable focus servo.
7. Use MANUAL SEARCH REV (<<) to position sled at beginning of disc.
8. Press PLAY. This enables the spindle servo. Disc should now spin up
and lock at at around 500 rpm. If disc does not start or appears not
to reach correct speed, check voltage on spindle motor. It should be
greater than 2.5 volts during spinup. The most common cause of low
voltage is a dirty partially shorted commutator/brush assembly inside
the motor; clean or replace as necessary. WARNING: if the disc spindle
speed runs away, turn power off and wait for spindle to stop completely.
VCO control may be set to high; turn counterclockwise 1/4 turn and start
from the beginning.
9. Press PAUSE. This locks the tracking servo. The display should show the
disc TRACK and TIME. Alternately pressing >> or << should move pickup,
then press PAUSE to start play again. Audio will be correct at output.
Correct display and sound only near end of disc indicates a spindle
motor unable to achieve sufficient speed (see above).
10. Adjust the VCO control to the midpoint of range in which disc plays
correctly.
11. Set RF.OFS to the midpoint of the range over which play continues normally.
12. Set FO.GAIN to midpoint of range over which it locks. CAUTION: the disc
may enter a runaway state if you go to far. Check at both the beginning
and end of the disc. FO.GAIN may need to be increased if the player is
overly sensitive to bumps or disc wobble. It may need to be decreased if
sensitivity to disc defects is too high.
13. Set TR.GAIN to the midpoint of range over which it locks. CAUTION: the
disc may enter a runaway state if you go to far. Check at both the
beginning and end of the disc. TR.GAIN may need to be increased if the
player is overly sensitive to bumps or disc wobble; it may need to be
decreased if sensitivity to disc defects is too high.
14. Press STOP. The disc should unload. Exit TEST MODE by turning power
off and on again. Confirm that the disc loads properly and that the
directory comes up quickly and the music starts without excessive delay,
hunting, or hesitation.
15. Test forward and reverse search and seek functions for proper behavior.
Some slight adjustments to tracking balance or fine tracking offset may
be needed to equalize the forward and reverse search or seek speed.
16. The player should now operate normally. However some tweaking of the gain
controls may be necessary (as described above) for optimum defective disc
and track seek performance over entire disc.
If you have an oscilloscope capable of at least 5 MHz bandwidth, you can now
optimize the amplitude and stability of the 'eye' pattern at the RF testpoint
by going back and touching up the various offset (RF, focus, fine tracking)
adjustments. Unless otherwise instructed by the service manual, it is probably
safe to assume that the RF signal should be maximum when everything is properly
adjusted. For example, if TR.OFS is not set properly, you may find that the
RF signal amplitude *decreases* when the tracking servo is closed since the
laser beam is now consistently off-center with respect to the row of pits and
lands. (With the servo loop open, the beam was crossing tracks more or less
at random so it was sometimes centered!) For the Pioneers I have seen, it
appears that the FO.OFS and TR.OFS may *not* be set optimally by the static
adjustments (4) and (5), above.
Note: See Pioneer TEST mode description in the section: "Pioneer PD/M series test mode".
1. Laser Power - Normal mode. Press PLAY - Laser power should be set to:
.26 mW +/- .02 mW. Adjust VR1 to spec.
2. PLL VCO Free Run Frequency:
* Set the player to TEST mode.
* Press STOP to switch all servos off.
* Press TRACK FWD to enable the FOCUS servo.
* Press PLAY to enable the SPINDLE servo.
* Observe the waveform at pin 8 of IC8 (2/2) using a scope set to .5 V/div.
This waveform can be found easily at the legs of C47.
Note the center value of this waveform.
* Using a core driver, adjust VL1 (VCO coil) so that the center value of
this waveform is the same when PAUSE is pressed to switch on the TRACK
servo.
3. Tangential Adjustment:
* Enter TEST mode and load the TEST disc??
* Use the MANUAL SEARCH FWD key to put the pickup at the end of the disc.
* Press TRACK FWD, PLAY, and PAUSE in that order to enable all servos.
* Use the Scope to observe TP2, Pin 4 (RF Output). Adjust the Tangential
Adjustment Screw to obtain the clearest eye pattern. This is the
midpoint between the places where the pattern begins to deteriorate.
4. Tracking Offset and Focus Offset:
* Enter TEST mode.
* Adjust the voltage at TP1, Pin 9 TR (Tracking Return) to 0V +/- 10 mV
by turning VR2 (Tracking Offset).
* Adjust the voltage at TP1, Pin 3 FO.ER (Focus Error) to 0V +/- 10 mV by
turning VR6 (FO.OF, Focus Offset).
5. Focus Gain:
* Enter TEST mode.
* Press STOP to disable all servos.
* Adjust the frequency and output voltage of CH1 of the F.T.G. to 878 Hz
and .2 V P-P. What if I do not have an F.T.G.?
* Connect the F.T.G. adjuster. Right :-).
* Press TRACK FWD, PLAY, and PAUSE in that order.
* Adjust VR3 FO.GA so that the green LED just comes on. Right.
1. Laser Power:
* Remove the flapper.
* Player should be in focus search mode.
* Short terminals FD1 and R together.
* Laser power should be .24-.30 mW.
(Apply -9V +/- .5 V if the pickup is off the circuit board.)
2. HF Level:
* Monitor HS with scope. Peak to peak level should be between 1.5 and 2.5 V.
3. Focus Offset:
* Set the TEST disc to PLAY. Make the adjustment at the center of disc
rotation (35 DHS).
* Connect the oscilloscope to HS. Adjust VR101 for the best eye pattern.
4. Tracking Gain:
* PLAY mode.
* ACVM to terminal Q and VE.
* Apply 800 Hz, 100 mV rms to TD1 and GND with a 220K resistor in series
from the audio oscillator.
* Adjust VR104 so that ETE = (EQ + 5 dB) +/- 1 dB.
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