TJB wrote:
"Mark D. Zacharias" wrote in
t:

TJB wrote:
"N Cook" wrote in
:

TJB 2lazyToGet@one wrote in message
...
Need some help please, please, on a Yamaha CD Player model cdc-60.

Just replaced the laser unit and it detects the CD and the spindle
motor starts up ok. Hit the play button and the unit plays okay
for about 15 minutes then starts to slow down, speed generally
wanders around and eventually stops and indicates there is no CD
present.

Is this likely to be a motor problem? If not any hints? This unit
is not the best to try and work on as you can't get to anything
while the it is playing

Thanks for any help
TJB

Try electrically disconnecting the motor (cut trace maybe) and
running it, the motor in isolation, from a bench power supply to
see if its a bearing problem.
Only low voltage, 1 to 2volts at most usually


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/





I did try running the motor from a low voltage and it ran okay but
maybe I should let it run for 30min or so and see what happens???

TJB

They had problems with shorted brushes on those motors...

Mark Z.




Is the problem I described above a symptom of shorted brushes. I
originally though it may be an overheating problem. Are there any
other faults which could manifest themselves as described?

Is it possible to clean/repair these motors or do you simply just go
and buy another one?

Thanks for the help so far
TJB

The motor can be checked with an ohmmeter at a low ohms range setting, while
SLOWLY rotating the motor. It should normally read 10 to 12 ohms or so. The
reading will vary while turning, but should not be short-circuit or open at
any one spot in it's rotation.

It is often possible to clear the short using an aerosol cleaner / lubricant
with a pinpoint applicator, sprayed through the slits at the bottom, aimed
at the brushes, while rotating manually, alternating with blowing it out
with a compressor. It's usually necessary to repeat several times before the
short clears. Blow out the excess cleaner with the compressor. You really
need to understand the construction of small motors so you can "aim" the
cleaner at the brushes.

Mark Z.