tomas@dna.lth.se (Tomas Richter) (06/27/90)
Symptoms are usually: Disc skips, or takes long time to start playing.
Noise from the player higher than normal.
Equipment needed for coarse adjustment: DVM, oscilloscope (1 or 2 channels,
10 MHz, 0.1 V/div or better),
frequency counter (10MHz, accuracy
and resolution better than 1KHz)
AND... a service manual (probably
about $10-15).
You will also need a good disc (a disc with few errors and well centered
hole). The manufacturers have special test discs, but any good disc will do.
To perform a complete adjustment you will also need something to measure
the output from the laser and the frequency response of the servo circuits.
You will also need a distorsion analyzer to adjust any adjustable bits
in the D/A converter.
The laser is probably good, and the servo circuit adjustments have enough
tolerances to be adjusted with the oscilloscope and your ears, so forget
about the special equipment. Don't touch the D/A trim pots! By the way,
if it's a Sony, the laser can't be adjusted at all! Some pick-up types have
a diffraction grating adjustment possibility, but I don't remember the
procedure for this (I think this was a Mitsubishi player???).
It might be wise to use a static-free work place when you poke around in
the player since many of the circuits in it is more or less static-sensitive.
The coarse adjustments are easily done, but it will take some time if it's
the first time. The servo adjustment might not be optimal the first time
you try, but you will notice if the problem gets better or not.
Try again if you are not satisfied the first time.
There might also be some mechanical adjustments of the sled and the
optical pick-up assembly. These adjustments vary depending on the pick-up
positioning mechanism (linear motor, voice-coil, rack-and-pinion or
whatever the type might be).
I have adjusted my almost ancient Sony CDP-101. The first 15 minutes after
power-on it skipped violently or completely refused to play at all. It
also was very picky about my discs and didn't like some of them at all.
I don't know exactly which adjustment it was that helped, nothing was
neither very wrong nor completely correct. Now it plays any disc without
problem. The manual told me to connect some pins to each other or to ground
when performing certain adjustments and I did so. Unfortunately the player
had never read the manual, and did not behave as it was supposed to. When
I disregarded some of these instructions, it was much easier...
So, if the player doesn't behave as it should, just try to make the
adjustment anyway if it seems possible.
One year ago I also bought a new player, CDP 557ESD (in USA and Canada
it is called CDP 707ESD), and noticed that it has fewer adjustment points
than the old one.
Be careful, and read the whole adjustment section in the manual before
starting.
Good luck!
--
Tomas Richter ! INTERNET: tomas@dna.lth.se
Dept of Computer Sciences !
Lund University, P.O. Box 118 ! PHONE: int+46-46104929
S-221 00 Lund, Sweden !