Ok well I will start from the beginning. I was attempting to mod one of my xbox's dvd drives. I tweaked the pot to a slightly lower resistance, but when I put it all back together the drive did not work.

Now this drive is one of the newer philips ones. I have already modded 3 thompson drives without fault. I pulled it appart and took a look inside again. After a lot of looking, I worked out the dvd was not spinning up. I'm not sure if this is caused by the laser not seeing a dvd or not.

Any thoughts? Could it be the motor or have I just screwed the laser?

I did notice something strange when I measured the pot it was over 1100ohms. I have checked around on the net, and most people were getting around 500ohms resistance. Because of this issue, I decided it was best to only lower the resistance to 1000ohms, and then retest because it would be less likely to do damage than reducing the resistance in large amounts at a time.

But anyway, my real question is:

Does the DVD drive spin up the DVD and then the laser reads it, or does the laser read the DVD and then spin up the drive spin it up?

Usually when you fry the laser, the drive doesn't spin. I have only had this happen twice on an xbox but it is very common with PS2 consoles drives.

No the control IC spins the driver once Drawer sense in is recognised at its input.
Tweaking the pots is a dangerous game and I fear you will now need a new laser. Once you do damage it still will not work even if you put the pot back

Yeah I know you cant repair the laser just replace it.
Oh well, I thought I would ask before I buy a replacement laser.

Thanks

ALWAYS tweak in increments of 50 ohms or less... try a CD, if that spins up, you probably fried the more touchy and fragile DVD laser. Best of luck finding a laser for the new drive though. Resistance values differ with every drive, thats why they put pots on in the first place, if yours is set to 1100 ohms, there is a reason behind it.