PlayStation disc spins and stops: spindle height, clamp and motor

Symptom

Reading the disc behaviour

A disc that spins up to full speed and stays there while the laser seeks is mechanically healthy. A disc that repeatedly speeds up and slows down is losing focus, which means the spindle height is wrong or the disc is not sitting flat on the hub.

A disc that slips, or that can be stopped with a finger while the motor is running, has a worn clamp or a worn hub. Slipping produces a characteristic chattering sound that owners describe as the console grinding.

A motor that does not turn at all, or that needs a push to start, has a dead spot in its windings. That is a motor replacement and nothing else will fix it.

Diagnosis

Mechanics before optics

Take the drive out of the shell and remove the top cover so you can watch the disc while the console runs. Watching the disc behaviour with the console assembled tells you very little; watching it with the drive exposed tells you almost everything.

Measure the spindle height with the disc removed. The hub should sit so that a disc rests level, and the clamp should grip it evenly around the whole circumference.

1. Run the console with the drive exposed and watch the disc. Note whether it wobbles, slips or sits off-centre.
2. Press gently on the centre of a spinning disc with a finger. If it slows easily, the clamp force is too low.
3. Check the clamp for a worn or glazed rubber ring. A glazed ring has a shiny surface where it should be matte.
4. Measure the spindle height against the service value for this revision, or compare against a known-good drive of the same model.
5. Spin the spindle motor by hand with the power off. It should turn freely and come to rest smoothly. A motor that feels notchy has a dead spot.
6. Measure the motor winding resistance across its terminals. Both windings should read within ten percent of each other.

Remedy

Clamp, height or motor

Start with the clamp. A glazed rubber ring can be refreshed by cleaning it with isopropyl alcohol, which removes the polished layer and restores grip. If the rubber is perished or flattened, replace the clamp assembly rather than trying to build up the ring.

If the spindle height is wrong, it has usually been altered by someone fitting a laser assembly without seating it properly. The correct fix is to reseat the laser sled and set the height with the proper gauge, not to bend the sled until the disc reads.

A motor with a dead spot must be replaced. They are a standard part and the swap is straightforward with the drive out of the shell, but the wires are short and stiff, so take care not to pull the connector off the board.

1. Clean the clamp rubber with isopropyl alcohol and re-test.
2. If grip is still poor, replace the clamp assembly.
3. Reseat the laser sled and set the spindle height correctly rather than bending anything.
4. For a dead-spot motor, desolder the motor wires from the drive board and fit a replacement motor.
5. Reassemble and test with three discs: a pressed game, a CD-R and a scratched audio CD.
6. Run for thirty minutes and confirm the disc does not slip as the drive warms up.