Sony WM-BF64 Drive Belt Repair

The pulleys on the WM-AF64/WM-BF64 are sufficiently wide with enough clearance to install slightly thicker 1.2 mm cross-section belts. Providing the belt does not touch the top surface of the motor body, it will work. I had a bag of assorted belts that I bought for two pounds on eBay and which came from China were handy as it had a belt that was the correct size. A belt with a circumference of approximately 190 mm appears to be a good fit with sufficient tension.

Using my Sony diagnostic tape I measured the torque figures during playback, fast forward, and rewind, and they were extremely good due to the thicker belt. I also used the Sony WS-48A test tape to adjust the speed of the motor. I am glad I liberated the complete set of test tapes whilst working for the Sony Corporation as a service engineer. Back then, these tapes were not worth much and we used to throw a mangled one in the bin almost each day, but today, they are priceless.

Note: Resist the temptation to spin the black plastic pulley (or any of the pulleys for that matter) with your thumbs, as you will likely cause a misalignment of the mechanism, not to mention break the programmed gear. I have seen "experts" spin it around for fun without knowing what they were doing.

The original belt on this unit had reverted to liquid state, and some parts of it were stuck around the pulleys.

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