Audio Systems: Onkyo DX-C100 does not register CDs, carousel tray, laser diode


Question
Bought this 5-cd changer on eBay from people who shipped it to me from Maryland (I'm in Arizona).  They said it worked fine when it left.  They locked the carousel before shipping but when it arrived the carousel was not locked.  There was a fair amount of dust on the unit and on the carousel tray surfaces.  I started by wiping the dust off all the easily-accessible surfaces with a damp rag.

The problem is that the player will not register CDs -- factory or otherwise -- placed in the carousel tray.  Carousel opens and rotates fine, closes, then the machine goes through the indexing process and concludes there are no CDs in the tray, and the display (disc and track number) reads all zeros.  I blew out everything I could with canned air but this did not help.

Does this machine have a readily-accessible system for identifying the presence of CDs that might have gotten dirty in shipping?  In other words, can I just clean this thing and get it to work?  It's a solid unit and I'd like to keep it.  The seller refunded my money so I can just recycle it if it's hopeless, and I know the cost of commercial repair probably exceeds the replacement cost, so I'd have to do it myself.

Answer
It is most likely that something has caused the laser beam to fail to reach the disc surfaces.  This can be from either an optical obstruction or from a weak/dead laser diode.

If diode needs replacement it will be expensive and requires difficult alignment using test recording and setting for null, focus and error correction settings.

If obstruction is could be from dust build up on the lens over the laser diode. This you can improve by cleaning off the lens with a cotton Q-tip.  Do not use any chemicals other than water.

Maybe that will cure it.  Let me know the outcome or further questioning if you need.