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.General System ProblemsCD player is totally dead
Check input power, power cord, fuse, power supply components. Locate the
outputs of the power transformer and trace them to the rectifiers and
associated filter capacitors and regulators. While the actual voltages
will probably not be marked, most of the power in a CD player will be
typically between +15 and -15 VDC. Sometimes, the voltage ratings of the
filter capacitors and/or regulators will provide clues as to correct power
supply outputs. Don't forget the obvious of the line cord, line fuse
(if present), and power switch - or outlet. Most component CD players use
linear power supplies so troubleshooting is straightforward.
Portables CD players and CDROM drives often use DC-DC converters to produce
the various voltages required, and these are much more difficult to
troubleshoot even with a complete service manual. Doing anything other than
checking for shorted or open components is virtually impossible without an
accurate schematic. If an incorrect power adapter was used (or this happened
when you plugged or unplugged the power connector of a CDROM drive with power
on - a no-no), then major damage can result despite the various types of
protective measures taken in the design. However, check for the obvious - a
blown fuse on the mainboard near the power connector. These may be
picofuses(tm) which look like little green resistors, IC Protectors which look
like tiny transistors with only 2 legs, or something else marked F, ICP, etc.
You might get lucky.
I inherited a Sony Discman from a guy who thought he would save a few bucks and
make an adapter cord to use it in his car. Not only was the 12-15 volts
from the car battery too high but he got it backwards! Blew the DC-DC
converter transistor in two despite the built in reverse voltage protection
and fried the microcontroller. Needless to say, the player was a loss but the
cigarette lighter fuse was happy as a clam!
Moral: those voltage, current, and polarity ratings marked on portable
equipment are there for a reason. Voltage rating should not be exceeded,
though using a slightly lower voltage adapter will probably cause no harm
though performance may suffer. The current rating of the adapter should
be at least equal to the printed rating. The polarity, of course, must be
correct. If connected backwards with a current limited adapter, there may be
no immediate damage depending on the design of the protective circuits. But
don't take chances - double check that the polarities match - with a voltmeter
if necessary - before you plug it in! Note that even some identically marked
adapters put out widely different open circuit voltages. If the unloaded
voltage reading is more than 25-30% higher than the marked value, I would
be cautious about using the adapter without confirmation that it is acceptable
for your player. Needless to say, if the player behaves in any strange or
unexpected manner with a new adapter, if any part gets unusually warm, or if
there is any unusual odor, unplug it immediately and attempt to identify the
cause of the problem.
See the document: Audio Equipment and Other
Miscellaneous Stuff for more info on linear power supplies. See
the document Small Switchmode Power Supplies
for more info on DC-DC convertors.CD player is operational but there is no display or partial display
Where the display is very dim or totally out, suspect one or more burned out
bulbs for the backlight. Sometimes the display uses miniature incandescent
lamps and these burn out. Usually, alternatives to the high priced exact
replacement bulbs can be located. Test the bulbs with an ohmmeter. Measure
the voltage across the light bulb connections and then replace the bulb with
one of about 25-50% higher voltage. These may not be quite as bright but
should last forever.
If the light bulbs are not at fault or there are no light bulbs, then check
for power to the display including bad connections or connectors that need
to be reseated. There could also be a power supply (e.g., missing voltage
to the filament or segments for a vacuum fluorescent display) or driver
If only portions of the display are bad - some segments on multiple digits,
for example, check for bad connections to the driver chip. The displays
are usually multiplexed meaning that a single output of the driver chip
actually is used for the same segment in multiple digits or even apparently
unrelated words or icons. Thus, a single failure can result in strange
display behavior. If no bad connections are found, the driver chip or actual
display could be at fault. Since the player works otherwise, unless you are
a purist, it make sense to just leave it alone.
In the case of a portable or car CD that uses a 'zebra stripe' type rubber
compression connector, cleaning the rubber piece, display, and circuit board
with alcohol and reinstalling may solve the problem. If it uses a glued on
printed flex cable, DO NOT attempt to remove it. Take extreme care when
working on such equipment as it is virtually impossible to repair a cable
of this type should it tear or pull free.CD player ignores you
Symptoms are that the display comes up normal when power is turned on
but all (or certain) commands are ignored.
This could mean several things:
- Front panel problem - one or more buttons are not responding. Reseat
internal cables, clean or replace offending push button switches. If
your CD player has a remote control, see if it operates correctly.
- Reset failure - the player has failed to reset properly and is not ready
for user input. Try pulling the plug for a couple of minutes to see if
it will reset. Check power supply voltages, clean and reseat internal
- Controller and/or driver electronics for the affected functions are
defective. Check power supply voltages, reseat internal connectors.
For all but the first one, a service manual will probably be needed to
proceed further if the problem is not with a bad power supply or bad
connections.Drawer does not open or close
If the drawer doesn't open when the front panel button is pressed, listen
for motor attempting to open the drawer. If you hear it whirring but nothing
happens, check for an oily/loose belt or other mechanical fault like a gear
loose on the motor shaft or a slipping rubber wheel. Such a gear is probably
split and a replacement will be needed. Rubber parts may be cleaned for a
temporary repair but replacement will be needed eventually.
If there is no attempt, motor, control chip, or front panel pushbutton (try
with the remote if you have one to eliminate this possibility) could be bad.
Sony players seem to have a built in timer that triggers the belt to go bad
after the warranty runs out. Also see the section on "Small Motors in CD
Another slight possibility is that the player has gotten into a "Dealer
Antitheft" mode which prevents people from stealing CDs or DVDs from demo
units in a store. Consult your user manual or ask the place where
you bought it for the key sequence. to reset it.Drawer operation is erratic
You are about to remove your favorite CD but the player beats you to it,
closes the drawer, and starts playing it over again. Or, the drawer
reverses course halfway out. Or, the drawer motor continues to whir
even after the door is fully open or closed and the front panel is
This is usually due to dirty contacts on the door position sense switches.
There are usually 3 sets of switch contacts associated with the drawer
mechanism. If any of these get dirty, worn, or bent out of place, erratic
operation can result:
- Drawer closed sense switch - dirty contacts may result in the drawer motor
continuing to whir after the door closes and the front panel may then
be unresponsive. Eventually, the drawer may open on its own.
- Drawer open sense switch - dirty contacts may result in the drawer motor
continuing to whir after the door opens and the front panel may then
be unresponsive. Eventually, the drawer may close on its own.
- Drawer pushed sense switch - most CD players allow the user to start play
by gently pushing on the drawer which depresses a set of switch contacts.
If these are dirty, the result may be the drawer deciding to close on its
own or reversing direction in the middle of opening or closing.
The solution to all these problems is usually to simply locate the offending
switches and clean their contacts. These switches contacts are usually not
protected from dust, dirt, and grime so that these types of problems are
If the drawer simply doesn't respond to your wishes - sometimes, there may be
a bad belt or bad motor.
- Sometimes, how long the player has been powered will affect the
'stickiness' of the belt - leave it on long enough and the belt will loosen
and be too weak to operate the drawer. See the section:
[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط].
- The drawer motor may have a 'dead spot' or be partially shorted. See the
chapter: [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط].