I recently obtained a couple of compact Macs with Sony SuperDrives. In both cases the drives wouldn't read disks. I did the usual servicing of the insert/eject mechanism and both inserted and ejected disks fine, but they still wouldn't read disks. In both cases the issue with the drives was that the top head was not touching the disk. I managed to diagnose this by connecting the drive to the computer with the cover off and watching as it tried to read the disk. Then I simply pressed down on the head with my finger so it would touch the disk. Once I did that the drive would start to read and write.
This seems to be a common problem with these drives because they use a leaf type spring on the top head. What typically happens is when the machine is stored away for years on end with no disk inserted, the drive head is held in the open position and this causes the head to stay in this raised position. The other cause would no doubt be people unwittingly raising the head too far in order to clean between the heads. This would cause the leaf type spring to bend upwards.
I'm glad to say I've found a fairly easy fix to this problem. I've repaired both drives and they are now working fine. So I thought I'd write a guide on how to fix this head spring problem. The fix involves two things:
- Bending the leaf spring on the top head back down
- Adjusting the internal spring inside the head to further drag the top head down on the disk.
In order to perform these tasks you need to remove the head from the drive. This is a fairly simple process. There are two small screws holding the head down. These screws clamp down the slide bar on the right side of the head (looking from the back of the drive). Then there are two small card cables which simply pull out of their sockets. These need to be removed. Once both those things are done the head can be removed from the drive.
To bend the leaf spring back down again, you need to insert a small flat head screw driver towards the back of the head assembly. There is a small metal plate where you can rest the screw driver.
Push it in enough to spread the heads apart. Once that's done you push down gently on the top head. The screwdriver acts as a fulcrum forcing the spring to be bent back down.
The second fix involves moving the position of the small spring inside the head to increase the tension on the top head. On the bottom of the head assembly there are three small adjustment steps that enable you to increase the tension on the spring. But I've found that even moving the head to the third position is not enough to provide enough downward pressure on the top head. So my solution was to notch out a fourth position further away. I used a broken off piece of hacksaw blade to create the new notch. This increases the tension on the spring enough to provide the required down force.
Internal spring moved to the fourth position.