Vocopro dvd-duet model, doesn't recognize cd is loaded; won't play cd. help. Doug Barnes
You must clean the lens you must use very
little pressure. Take a cotton swab and barely moisten it with plain,
non-scented, or oily type alcohol. In a swirling motion, very gently rub the
lens until you’ve covered it entirely. Then repeat using the dry end.
Now, if no cables are disconnected,
and if you can verify nothing is touching the TV or DVD chassis, you can plug
in the unit and check if this helped the player to "see" again. Most
of the time you can check as is, though on the combo units you're going to have
to slide the chassis assembly all the way back into the cabinet to get it to
work because the cables are often too short. If this didn’t fix the problem,
please read on.
Other things to check
If the cleaning didn’t help, don’t
despair just yet. You can see if there’s a problem elsewhere in the unit by
using a few simple tricks and tips.
First thing you want to see if the
unit’s laser is in good working order. This method isn’t foolproof, but most of
the time works admirably. When you insert a disc, see if you can look up
underneath where the disc sits on the turntable. Observe the laser lens going
up and down. If the lens is trying to focus, that’s good! After a few seconds
of the lens trying to focus, the platter should start to spin. On almost every
CD/DVD unit I've encountered, the unit won't spin unless the laser has properly
focused on the surface of the disc.
f the unit spins up and and then
shuts down, you should check and make sure the laser pick-up assembly slider
mechanism is working without any obstructions and that the small chrome rail
that it slides on is slightly greased. Don’t go overboard with the grease
though, as too much can cause all sorts of problems.
The slider mechanism, depending on
the age of the unit and the manufacturer, consists of the small chrome rail, a
drive motor, a small gear assembly, and (in some units) a small belt that
drives the slider unit via the motor. This small belt causes all sorts of
problems. If the belt is broken or slipping, it can cause skipping, dropouts,
or simply no start up at all. Also, if the belt breaks in the middle of the
disc, the drive mechanism gets hair or dirt wrapped up into the gears, or the
pick-up assembly doesn’t return to the start position (called home), the unit
will (99% of the time) refuse to release the disc, causing it to become stuck
inside the unit. There’s a little micro or leaf type switch located at home
position that sometimes gets dirty or breaks and, causing this problem also.
If the disc starts to spin slowly
and doesn’t come up to speed, the spindle motor that’s attached to the
turntable platter is a common problem. There could also be a problem with the
spindle motor driver controller IC or the power supply regulator that supplies
voltage to the driver IC. If the disc starts to spin and then spins really
fast, or stops and starts to spin backwards, your problem is the laser pick-up
assembly or the servo control circuit.
Also, in a DVD/CD player there are
many complaints where the disc gets stuck inside of the unit. This could be as
described earlier, but there’s also what’s called a drawer/disc tray opener and
closer mechanism to contend with. On many models, old and new alike, there’s a
small belt that goes bad and wont let the tray open. You can usually put your
ear very close to the front of the unit and, if this is happening, hear the
motor spinning when you press the eject button. Another cause is the nylon
gears, which can get jammed up with dirt and dust. Also, in other cases, you
could have a motor problem, or the driver IC could be at fault. If you suspect
that the motor is at fault, simply measure the voltage on the tray motor while
pressing on the eject button. If the voltage comes up between 6 to 12 volts,
depending on the manufacturer, then the motor needs to be replaced.
If you continue to have problems
after cleaning and checking the other things listed above, you may have a
problem with the player's alignment. Of course, one of the problems you'll face
checking alignments on a DVD/CD player is that you’re going to need to use an
oscilloscope on most of them. If you have the proper tools and equipment, the
first thing to look at is the RF pattern of the unit while its playing. It
should be a sharp and clear pattern. If it's dull and smeared, then the laser
could be weak.
Also, in these units are very
critical alignments called the focus/tracking gains and offsets. When these
alignments are off, it can often cause intermittent troubles. As the unit ages
and parts change value, so do these alignments, and will need to be checked. In
my time as service technician repairing DVD/CD players, 65% of the laser
pick-up assembles I have tested were good and only needed a small adjustment.
Today's technology makes it unfeasible for a shop to hook up a DVD/CD player,
and even some recorders, to their equipment and make these adjustments because
of the cost involved.
Jul 15, 2008 |
Audio Players & Recorders