Sony MDS-S30 belt replacement

Should be valid for MDM2 mechanisms, including but not limited to:

  • MDS-302
  • MDS-303
  • MDS-S35
  • MDM-X4

This is an easy issue to diagnose because the device will fail to accept a MiniDisc fully. Attempting to insert a MiniDisc will result in it being stuck with about 10% remaining outside the slot. Removing the MiniDisc can be difficult due to lack of gripping surface and tension from the internal mechanism, but it can be done without damage.

The root cause is a broken or deteriorated belt.

Ordering the proper part can be done by searching for part #4-967-656-01. Seen in the illustration below as “ref. no.” 108.

I don't want to understate the importance of getting the proper belt. The proper belt is neither too tight (could damage pulleys) nor too loose (slippage). However, if scarcity is a problem, I used a square belt (just over 1mm) from a “variety pack” that measured about 30mm in diameter.

I arrived at this size based on testing with various sizes and shapes (flatter belts are not appropriate).

As always, disconnect the AC/mains before working on any electrical device!

The MDS-S30 has 5 screws securing the case: 2 on the left, 2 on the right, and one at the top of the rear panel.

After removing these, and starting from the rear, gently spread the bottom “flaps” of the case and lift from the rear. You'll notice a small “loose” cable near the front of the unit (internally, at the top of the display portion) that may be for ground to the chassis.

You'll see the MDM2 loading mechanism near the front slot. There is a large metal shroud covering most of the mechanism, but it's not necessary to remove it. You should have access to the belt and pulleys via a top and rear opening. See the following pictures with red arrows.

These images show the replacement belt in place, but you may see no belt or remnants of a belt that may look melted/degraded. Carefully remove what's remaining with toothpicks, cotton swabs, etc. and you may need to use 91% isopropyl alcohol to clean residue from the pulleys.

Though it may seem tricky, it's entirely possible to do this without removing the metal shroud. I recommend two sets of tweezers or tweezers and a small stick or probe.

Begin by passing the belt under the shroud towards the small pulley. Loop it around the small pulley and keep a finger on the small pulley to keep the belt in place.

Now, using tweezers, gently pull or hook the belt towards the larger pulley. You will be doing this horizontally under the shroud, but I have done this many times so just be patient and careful. Once looped over the larger pulley, the job is complete!

If you must test this before closing it up, you can plug the device into AC/mains and insert a disc to verify operation. Again, I don't recommend this, but if you do so - do NOT reach in and touch internal components. A visual verification is sufficient.

Be sure to remove power and replace the cover by reversing the steps taken to remove it.

  • guides/repair/mds-s30-belt-replace-fix-disc-intake-eject.txt
  • Last modified: 6 weeks ago
  • by hien34