Abstract: An environmentally controlled media defect detection system for Winchester disk drives includes a testing cabinet which is divided into two sections. The first section is maintained at an environmentally controlled elevated temperature for testing Winchester disk drives at elevated operational temperatures above ambient room temperatures. The second section is thermally insulated from the first section and contains a plurality of disk drive test units. One test unit is coupled to each Winchester disk drive being tested, and the test units have the ability to apply digital signals to the drive for writing and reading signals onto tracks of the drives, determining malfunctions, and imperfections in the disk media of the hard disk drive systems.