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PCM 1 CD Drive Repair

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Last weekend, I grew weary of my Porsche Communication Management system not working. I have a '99 C4, so it has the first-generation 8-bit PCM 1 system. It kept acting like it could not read the CD, and after cleaning the disc helped, I decided to get ambitious.

I figured the CD-ROM drive was toasted anyway, so...I removed the CD drive from the dash. I unplugged the connectors at the back, and proceeded to open the unit up in an attempt to access the laser lens assembly in order to clean it. I managed to do it, and (on the second try) was able to reassemble the unit properly and have it reading the disc slightly better than before. I'm sure this is..."frowned upon"...by Porsche and by your local dealership, but from a technically-oriented customer's point of view, why would I buy a brand-new unit for $1500 (or a rebuilt one from my dealer for $1150) when I can spend a grand total of 30 minutes and $0 to get my old one working once again? Why indeed...for $1500, I can buy a Pioneer single-DIN in-dash unit with a slide out LCD screen, DVD-based GPS navigation, and it plays CDs and DVDs right from the dash slot...The whole Porsche system is not a very compelling bargain considering the wealth of FAR-superior aftermarket products out there. They just don't have gloss-black oval-shaped buttons.

Sp anyway...this effort was born out of frustration with the potential expense at the dealer. Why on earth would a $20 CD-ROM drive and maybe $100 worth of GPS electronics cost $1500? To add insult to injury, they wanted to charge me an hour's worth of labor ($79/hour at my western Michigan dealership) just to swap out the new unit for the old. I mean, even if you include entering the code, the entire process of swapping out the CD drive unit can be done (and I'm dead serious) in less than 3 minutes.

I did find two things that I could do to restore performance of the unit. First, cleaning of the lens with a dry Q-tip (or with some tape head cleaning solution) can help the drive read the disc better by not having to look through a dirty lens. Second, there is a rubber-coated roller that acts to take in and also eject the disc. If this roller gets dirty it can slip on the disc and you may have a hard time getting the disc out. This roller can be cleaned once the unit is taken apart.

I found that there was really no dust inside the unit and that my roller was in near-new condition. But the unit seems to work better/read the discs better after doing this. Did it really help that much? I don't honestly know. I don't believe the flap covering the disc opening allows much dust in if any, it's very well protected. Thus, I think a dirty lens causing problems...is a longshot. Thus, I don't think disassembling the unit is really a good idea if this is all you're trying to do. It's very difficult to access and clean the lens without taking the whole thing apart, but since it's going to be pretty clean in there to begin with, you may be wasting your time. The disassembly process is only for the mechanically-inclined. It's a complex and delicate mechanism with many very small parts, and is not for the faint of heart.

That said, I had a lot of fun doing it. I figured it was broken anyway, so I just dove right into it. Turns out I put it back together properly, and it actually works a little better than it did. Now I just need to calibrate the system (see Loren's reply to the Calibrate PCM 1 post), then it should really work well. I took a load of digital photos of the disassembly process if anybody would like to see them. At the very least I can maybe post a DIY on how to swap the unit out of the dash. Any interest in this?

Lastly...I found it odd that I removed the unit from the dash and unplugged it (with the car battery still connected), took it apart, reassembled it, re-installed into the dash, found it wasn't working right, removed it/disassembled it/reinstalled it again, and...never once did I have to enter the code. Hmmm...how peculiar...

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