I'll grant (hee hee... grant... that's your name) you that a good portion of troubles with CD heads is caused by dirty optics. Not long ago I rescued a deck owned by a friend of mine that had a fine coating of red clay dust - from the long driveway he lives off of - spread just about everywhere in the deck (not to mention the whole interior of the truck). The early units had issues with failing lasers due to operating under high temps. Take an early deck that had hot running innards, stick it in a vehicle sitting in the hot summer sun, and it did not take long for the operating temp of the laser itself to blast past 80C or more. This would cause a degradation in power output, getting to the point where there was just not enough oomph to get a good signal back through the pickup optics. Some units could be saved by gently turning up the laser power (often the only trimpot inside a modern player), but only for a short time.
The mechanicals that drive the sled are often culprits, some cheap units having a simple little leaf switch for detecting the home position of the sled which get dirty or pushed out of alignment, and some makers who insist on using a rubber belt between the sled motor and the rest of the gearing forget that rubber bits like that in a car go bad in relatively short order.
Strange that the hall sensors are being the cause of problems, since the idea behind them was to eliminate mechanical contacts. Some units, even my early Alpine CD unit in the old Dart (the first Alpine unit sold in my state in '85, it even got some mention in a local trade publication) used an optical sensor suite that followed the disk through the loading transport, provided all the home position sensing for the sled and the loading mechanism, and even the status of the drive door. That part was flawless to this day. What did go, almost exactly a year after I bought the thing, was the laser. I had it replaced under warranty, and I fitted the overhead console I made to hold the player (it was only a CD deck, meant to go along with an existing radio/cassette HU) with a 40mm fan to help keep the unit cooled. It helped. The deck still works to this day (unlike the car it's mounted in).
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timeasmymeasure
no subject
Date: 2008-04-09 03:07 pm (UTC)The mechanicals that drive the sled are often culprits, some cheap units having a simple little leaf switch for detecting the home position of the sled which get dirty or pushed out of alignment, and some makers who insist on using a rubber belt between the sled motor and the rest of the gearing forget that rubber bits like that in a car go bad in relatively short order.
Strange that the hall sensors are being the cause of problems, since the idea behind them was to eliminate mechanical contacts. Some units, even my early Alpine CD unit in the old Dart (the first Alpine unit sold in my state in '85, it even got some mention in a local trade publication) used an optical sensor suite that followed the disk through the loading transport, provided all the home position sensing for the sled and the loading mechanism, and even the status of the drive door. That part was flawless to this day. What did go, almost exactly a year after I bought the thing, was the laser. I had it replaced under warranty, and I fitted the overhead console I made to hold the player (it was only a CD deck, meant to go along with an existing radio/cassette HU) with a 40mm fan to help keep the unit cooled. It helped. The deck still works to this day (unlike the car it's mounted in).