Overview

• On June 17, two non-revenue and two revenue E8 series trainsets experienced power supply stoppages, and a fifth set failed on June 30
• July investigations identified misoperation of semiconductor circuit boards in power units produced after a specific date as the root cause
• Affected trainsets were removed from solo service and grouped by manufacturing batch for focused inspections
• Interim measures have included reduced train frequencies and mandatory passenger transfers at Fukushima station on the Yamagata line
• Most Yamagata Shinkansen services will return to the standard timetable on August 1 after quality-control enhancements, with a limited number of cancellations