Project Dreamcast - Repair

As I said in my previous post, the Dreamcast I bought on eBay was listed as "broken."  When I got the unit I plugged it in and turned it on.  The system powers on and the welcome screen comes up.  The controllers work as does the VMU.  But the system will not read any discs; neither Dreamcast games nor music CDs.  This is actually a very common problem with the Dreamcast - in fact it's probably the single biggest problem that happens to Dreamcasts.  The lasers they used in the system tend to wear out quicker than other CD players and games systems.

Step one is always clean the laser lens.  Very carefully use a Q-tip and rubbing alcohol to wipe the lens.  You can also use compressed air as there is a second lens further down that you can't reach.  Neither of these worked for me, so I moved onto the common "fix" found on the Internet.  Every CD/DVD laser assembly has a trimmer that adjusts the power of the laser lens.  Note, a lot of people call this a potentiometer, but the technical name is a trimmer, or sometimes a trimmer potentiometer, or even a trimpot.  Here is a picture of the Dreamcast laser trimmer.

If you turn this trimmer clockwise you increase the power to the laser, counterclockwise to decrease the power.  The idea is to increase the power to the laser just to the point where it reads discs.  Increased power reduces the life of the laser, so this is at best a short-term fix.  Some people report that counterclockwise worked for them, but this doesn't make any sense.  Either way, you SLOWLY turn the trimmer clockwise and retest.  This is a long slow process of increasing the trimmer, testing, increasing again, etc.

Following this process I got it to read music CDs every time.  But game discs are another matter.  I got it to periodically read game discs, but most of the time it failed.  After several hours trying different settings, I decided to punt and try installing a new laser.  I purchased a JVC SPU-3200 laser assembly.  This is a functional replacement part for the Dreamcast.  Here's a picture of the new laser.

Replacing the laser was surprisingly easy.  There is one important task to remember when installing a new laser.  To protect the laser against static electricity, there should be a solder ball on the bottom of the laser.  You need to use a soldering iron to remove this solder ball.  After doing this you can reassemble the Dreamcast and test your new laser.

With the new laser installed, I tried a music CD.  It read the disc perfectly - this is good, I know the new lens is working.  However, it still won't read game discs.  At this point I'm not panicked.  I honestly don't know if new laser assemblies ship calibrated or not, so all I might need to do is calibrate the laser.  However, before I touch the trimmer on this new laser, I want to look at the rest of the GD-ROM drive circuitry.  What if there is another problem that is preventing it from reading game discs?  Next time I'll cover the continued effort to repair the Dreamcast.