Koss CDP607 Portable CD player won't recognise CD

Does the laser head ' home ' ie move to the centre of the disc when the lid is shut ? Does the display look like it's wanting to read when you shut the lid, or does it stay completely passive ? Does it spin up the disc or make any noises ?

Common problems with portables are stuck lasers due to mechanical probs in the sled drive, bad switch contacts on the door sense switch, broken operating pin for same switch, and of course, worn out lasers which, with an

Arfa

Thanks for the reply! I opened it up, and upon pressing down the thing that would signify the player being closed (door sense switch as you said), it looked like it wanted to read, the display went from 00, no, for no CD. Anyway, the laser head does not move, and it seems rather dim, I imagine it must be a worn out laser like you said. Thought I'd post here, mostly out of curiousity :P.

If the laser does not appear to try to move when you fool the player into thinking that the door is closed by pressing on the switch, then this may be your problem rather than a defective laser.

You will not be able to tell just by looking, if the laser is genuinely ' dim ', as its wavelength is primarily in the infra red section of the spectrum, where your eye is not sensitive. Any red that you see is only down to spectrum leakage, but can generally be taken as a good indication that the laser is burning. Do not look directly into the laser, even though this is considered to be a " safe power " device. Only look from an oblique angle.

If the laser is burning, this will normally indicate that the laser is ' home ' and that the sense switch is correctly flagging this to the system control micro. As well as the laser burning, at this time the lens should also be moving up and down a significant amount as the optical block attempts to obtain focus. With most players, if no sensible feedback is received during the first one or two tries, the optical block will be moved a short distance, in case it is looking at a dirty or damaged disc at that point.

I would suggest that you apply gentle pressure to a solid looking piece of the optical block, using the tip of a small screwdriver, or similar, and try to push the optical block down its track, away from the centre of the disc. Even though the block is usually driven by a worm gear arrangement on portables, gentle force will usually cause the spring loaded pawl to slip, allowing the the block to be pushed up its runners. When you have moved it a couple of cms, push the door closed switch again, and watch what happens. The optical block should first run quickly back to the centre, then the laser should start to burn, and the focus search sequence should start. When no disc is found, the block should shuffle about a bit, and try again, before giving up with the " NO DISC " message. If this happens ok, it's worth then retrying it properly, and you might just find that it now works. If the optical block had become tight and got stuck, the act of moving it manually and then allowing it to return under its own steam, will often free it off enough to start working.

If it does, then the unit should be dismantled, and the laser sled drive carefully cleaned of all the old grease using IPA or similar, then relubed using floil if you can get it, or high quality very light synthetic machine oil, applied sparingly, if not.

Arfa

Thanks for the detailed reply! If I move the laser head away from the center, upon faking the closing of the player, it does return. However placing a CD halfway down onto the player, it tries to spin a little. So I imagine it is overall wear. I was generally curious, I didn't expect to have it working properly again, so it doesn't matter. Fixing it is a little too tricky for me!