BEWARE OF LASER RADIATION - DO NOT LOOK DIRECTLY IN TO THE LASER WHEN IT IS POWERED ON.
My Marantz CD63SE started playing up with an intermittent fault - the worst kind to trace! From cold sometimes it would play a disc and other times it would not - if left switched on for half an hour or so it could sometimes be persuaded to work. But it was getting worse - effectively making the player unusable. (In hindsight - the mechanism had been a little slow to start and change tracks for a while). The symptoms were that a loaded disc would not spin up and the player would just report 'no disc'.
A few weekends ago we had some friends stay and very kindly Rod brought his oscilloscope with him so we could trace the fault. After a few hours of tracing, downloading data sheets etc. the fault was traced to the mechanism itself. The load disc sequence was close drawer, focus laser, then spin disc. The drawer was closing OK, but the laser was not focusing properly, so the machine assumed there was no disc present and did not spin the disc.
The laser in the mechanism had aged and was not strong enough for reliable disc detection. This also turned out to be very temperature dependent - hence the half hour warm up trick working. This was tested by a short while in the shed getting the mechanism cold - it reliably didn't play any disc. Bring it in to the warm - a few seconds with a hair drier - it played discs reliably.
Now the fun part was getting the parts! I emailed and phoned several well known HiFi stores who wanted upwards of £40 - non refundable - just to open the box and tell me what was wrong. They would not just supply the parts - apparently Marantz will only sell parts to authorized service agents.
It turned out that a company I used many years ago for VHS spare parts, Grandata, also now stock CD mechanisms. A quick look on their site - one CDM 12.1 mechanism was on order and arrived the next morning!
(Update 9/7/2007: Thanks to David Draysey who contacted me saying that the CDM12.1 part is now labelled VAM1202/12).
(Update 14/08/2013: The VAM1202 unit is also available from CPC, Amazon and ebay).
(Update 11/02/2014: I am finding that some units are being supplied with non-rare earth magnets on the center spindle. In some cases I have found that this magnet is not strong enough to clamp the CD properly and may result in slight CD slip at start up).
Now - the fitting of the mechanism. I cannot stress enough that care should be taken with this process. I would also recommend the use of an antistatic wrist strap to prevent parts damage.
Tools needed - an antistatic wrist band, a crosshead screwdriver, a fine flat bladed screwdriver, a pearl catcher, and a fine soldering iron.
Remove the lid of the CD player - 6 crosshead screws. You will be presented with a view like this.
The mechanism is connected using 3 connectors, 1 ribbon cable and 2 wire connectors - don't pull on the wires - pull on the connector itself. The ribbon cable connector - the top edge lifts slightly to release the ribbon.
Photo 2: Mechanism connectors - black is ribbon connector, white are the 2 wire connectors (the 4 pin one does the drawer motor and sensor, the other 6 pin one does the spindle motor, the laser position motor, and the laser position switch).
Next remove the CD Drawer - this is done by gently pulling the tray out until it hits a stop. Insert a small flat bladed screw driver to release the drawer stop - see photo 3.
Next remove the mechanism assembly from the main case. Undo the 3 crosshead screws highlighted in photo 4. (I found a pearl catcher of use here to recover the screws). The assembly is then removed by lifting it and pulling it away from the front of the case.
Photo 4: Remove the mechanism - 3 crosshead screws (use a pearl catcher).
Put the main case to one side while working on the mechanism assembly.
On the side of the assembly you will find some cable clips - the ones holding 6 wires - gently remove the cables from these clips (photo 5).
Next turn the assembly over and remove the small PCB from the bottom - undo 2 crosshead screws (highlighted in photo 6), then slide the bracket in the direction of the arrow (highlighted in photo 6). The PCB can be carefully lifted. You can now see where the laser ribbon connector is - remove the ribbon by undoing the connector in a similar way to the ribbon connector on the main board.
Photo 6: Mechanism PCB - 2 crosshead screws and slide the bracket in direction of arrow.
With the PCB out of the way you can now fully see the laser mechanism. In photo 7 this is shown with the new unit on the right. The new unit has a smaller laser position motor.
You can now see where the 6 wires are connected. Two wires go to the spindle motor, two to the laser motor, and 2 to the laser position switch. Make a note of these and note that the two motors have coloured indentifying dots - the spindle motor has a red dot, the laser motor has a blue dot. Now unsolder these 6 wires.
As you turned the mechanism over you may have found that the sled wanted to fall out of the mechanism assembly. Have a look to see where sled pegs locate themselves in the mechanism - then slide the sled fully out to remove it - beware of the grease on the pegs! (the pegs are highlighted in photo 8).
Now with the sled removed turn the sled over and you can see the rubber anti-shock mountings - there are 4 - mine were made of a clear rubber (photo 9). These need to be removed - but beware there is a small barb (photo 10) to stop them being slid sideways. I found it easier to gently push them out through the mechanism with a small flat bladed screwdriver.
Now the old laser unit should be free and can be removed.
Now - being careful not to get the new laser unit lense dirty - you can fit it in to the sled. The rubber mounts do now slide in from the sides as the barbs will allow this direction of movement.
The remainder of the fitting is the reverse of that listed above, making sure that you fit all cables in their original paths and do not pinch them in any joints.