Expert: Cleggsan - 1/14/2010

Question
Recently replaced the power (on/off) switch on Rotel RCD 955-AX when unit would not power up.  Switch remedied that power up scenario; however, the CD platter spins at full-speed the entire time the power is on now.  There is no initial spin up and stop process and no disk can be played.

I can find no bad capacitors, no connections that are loose and all connections initially removed to replace switch have been restored to how they were found.  This is a factory switch for the unit.  I'm at loss for what has happened.

Answer
The switch may have solved the power problem but the spinning platter motor in the cd player is another matter.

This is a rather ancient cd unit and it is very likely that the operational components of the cd player mechanism and electronics have gone bad.  The motor is driven by  a servo system that keeps the disc running at a constant linear velocity - not a constant angular velocity like the old lp recordings.  So, the motor drive is under the direction of the controller portion of the cd  player electronics.  The speed of the motor is driven by the input of the digital information from the disc as read off by the laser diode.  

Therefore, if the diode is weak or lost its output there will be no signals to put the drive system into proper allocation.  If the controller IC is defective it will not generate the correct signals to control the motor speed.  And so on.

It will require some testing and measurements to determine the exact nature of the failure.  The cost may be prohibitive as well.

Just a note of explanation: These older players are very much inferior to the newer designs which have been perfected immensely in just the past few years.  So, unless you are intensely interested in keeping this one running, you may be wise to look at new merchandise.

But, let me know if you have any further discussion.