The story here is rather interesting, if I do say so myself. I acquired a Sony CDP-C345 5-disc CD changer. It supposedly did not work, but the exact nature of the failure was not known. I checked it out and discovered that the drawer would go in and out over and over again. My best guess was that the machine did not know when the drawer was open or closed and kept trying to “find itself”.
This machine was manufactured in the early 1990s and you can find them at places such as Salvation Army and Restore for a few bucks. They often turn up at yard sales. Many people have switched to the horrible streaming or inferior MP3 format so they have ended up as surplus. If the machine has stopped working properly it is often too expensive to have it repaired if, and I do mean “IF”, a repair shop can be found.
As it turns out, although the electronics in machines such a this one are sophisticated, the actual problems are often simple mechanics. In this case the problem was exactly that. You can find lots of videos and other information on the Internet describing repair procedures, so I will give this post the condensed version.
With a 5-disc changer such as this Sony model, there are several primary components that make the thing work. There is, of course, the laser pickup and associated mechanical system that reads the CD data and causes the pickup to move during playback. There is also the drawer mechanism that makes the drawer move in and out of the machine. The turntable system spins around and places the CDs in the pickup mechanism.
The turntable has two optical sensors. One sensor looks for a disc in the 5 spaces. The loading information is sent to the electronic “brains” of the machine so determine whether or not to skip a space when the turntable turns. The sensor shoots a beam of light into the space where there should be a disc, and if the light is reflected back the machine knows there is a disc in that space.
The other optical pickup is used to count the disc spaces in the turntable. It is hard to describe accurately, but there is a curtain-like affair around the bottom of the turntable that has slots in it. The optical pickup recognizes the flashes of light through the slots when the turntable spins, and the processor brains translates those flashes into the slot number. That is how the machine knows which disc space is which when you ask to play a certain CD.
If the CD changer is acting funny, knowing what these optical sensors do helps to establish a diagnosis. For instance, if the turntable continuously spins it might be because the sensor that reads which disc space is which might be having trouble finding the spaces, so to speak. This problem could easily be caused by a dirty or faulty sensor rather than a problem with the main processor. If it is a dirty sensor causing the problem, a quick cleaning will be a simple fix.
There is a mechanical switch-like affair under one of the gears. This switch helps the machine figure out what the “start position” of the player is. These machines need to know where to start before they can figure out what to do. If this switch thing is dirty the drawer mechanism may work continuously because it will not know when it is open or closed.
If one of the two belts in the machine breaks the drawer will not work, the turntable will not spin, and the machine will appear to be totally dead. Belts are very inexpensive and easy to change.
In the case of this CDP-C345 all I had to do was clean the optical sensors and re-align the gearing. Re-aligning is much like timing a car engine. The gears have to be in a particular position and the drawer has to set into that arrangement properly. One video I watched shows a technician using an oscilloscope and doing all sorts of fancy manipulations to align the gears. Most other videos show the machine being turned on and off, then back on a couple of times. The player is smart enough to re-set itself automatically. I did the on-off thing and the CDP-345 re-aligned itself, and once I placed the drawer on correctly the player figured everything out with no problems at all.
As I write this the CDP-C345 is playing a Lynyrd Skynyrd CD and it sounds fantastic! The frequency response is a stunning whale-song 2Hz to 20kHz and you can’t ask for better than that.
I know what some folks do not see the point of fixing and using this old equipment. Well, frankly, fixing it is a fun challenge. And second, you will not get the same effect by listening to Lynyrd Skynyrd through ear buds by way of MP3.
I am wondering what else I can repair. I am sure I can find something.