Thor said:
What are some simple and reliable methods of checking the laser in a DVD
player?
By definition the laser would include the layer that also plays audio cd's
as
well, but I am really interested in the video layer. I have DMM's and
such, even
a laser power meter but that is on the bulky side.
How much trouble is it to replace the laser(assembly?) and what equipment
is
needed? How about alignment, if it is needed?
I am looking at a finicky Sanyo DWM-400, about 3 years old.
I will give more info as needed.
Thanks for any help,
Thor
In general, there's not an awful lot you can do to 'test' an optical block,
as such. In general, if the unit plays CDs but not DVDs, or, more rarely,
the other way round, you have a better than even chance that it's the laser
(optical block) that's at fault. If your player is used a fair bit, then 3
years is not at all uncommon for the laser to be showing signs of wear.
Another good pointer is if the player starts freezing up after about 3/4 of
a full length feature film has played. This is when the player has switched
to reading layer 2 on the disc, which has to be read through the
semi-transparent layer 1, so consequently has less reflectivity of the laser
beam.
Other causes of poor playability are bad spindle motors, when they are the
brushgear'd little Mitsumi DC types, and (very) occasionally deposits on the
outer surface of the lens, particularly if it's a heavy smoking household.
Geoff in Israel who posts here, also tells me that it is more common to have
a dirty laser, if you live in a climate like his.
As far as replacing lasers goes, on most players, it's not a difficult job.
Often, the laser comes pre-mounted and aligned on a sub-deck, which also
includes the spindle and sled motors, and limit switch. Where this is the
case, it is pretty much guaranteed that it is just a 'drop-in' replacement.
Some lasers are supplied as just a 'bare bones' optical block. In most
cases, these will also just drop in, but some players, such as Panasonic for
instance, require the tilt to be mechanically adjusted. Some other players
have electronic setups to match in the replacement laser to the machine.
Most machines also have a degree of self diagnosis built in, but it's often
hard to get at unless you have a service manual, and sometimes a service
remote. In my experience, unless you have a particular liking for a player,
or if it's a HC system, and you have all its speakers and cabling 'plumbed
in' to your walls, the cost of a replacement laser is prohibitive, and you
might as well go and buy a new player, with a new 2 year warranty, at the
cheapest place you can find ...
Arfa