Customer Challenge
Alstom approached TP Matrix Ltd in January 2024 to explore support for their Class 390 SUH Box repairs. These units are critical to the fleet as the tilting system of the Class 390 vehicles is managed via sensors (gyros, accelerometers) on bogies, and a train-level “tilt processor” (TTP) that communicates with vehicle tilting processors (VTPs). Alstom faced prolonged lead times on repairs for the units. Failures were impacting fleet availability, with units often sidelined for extended periods.
Our Approach
TP Matrix conducted an initial assessment and repair of a two SUH Boxes, followed by trials of the repaired units. After a successful trial in October 2024, we were asked to provide a formal proposal for full repair and functional testing of the units.
During the engineering assessment, two primary causes of failure were identified:
- Water ingress – Moisture entering through connectors, compromising the internal electronics.
- Ageing network resistors – Over time, resistor tolerances drifted, leading to intermittent or complete failures.
Our engineering solution included:
- Replacing all network resistors as standard to restore performance and tolerance.
- Replacing weakened connectors where water ingress had compromised the integrity.
- Carrying out any additional repairs required to return units to full functionality.
- Comprehensive testing on bespoke test equipment designed by TP Matrix to validate performance before returning units to service.
Project Execution and Results
The repair programme officially commenced in June 2025. Since then, TP Matrix has repaired 60+ SUH Boxes, significantly helping to replenish float stock and reduce downtime. By addressing the root causes of failure, we have enhanced reliability and ensured the units meet operational and engineering standards.
Engineering Benefits
- Reduced repair lead times and faster return to service.
- Increased fleet availability and operational reliability.
- Proactive replacement of ageing components, mitigating future failures.
- Fully tested and validated units ensuring compliance with safety and operational requirements.
- This project demonstrates TP Matrix’s expertise in rolling stock electronics repair, providing engineering-led solutions that directly support operational efficiency and reliability for rail operators.
“We recently engaged TP Matrix to overhaul electronic boxes that connect with the bogie sensors across the entire Class 390 Pendolino fleet and the results have been outstanding. From the outset, their team demonstrated a high level of technical expertise and professionalism, ensuring the refurbishment process was smooth, efficient and aligned with our operational requirements.
“The quality of the work delivered was excellent, with noticeable improvements in reliability and performance post-overhaul. TP Matrix were responsive throughout, providing clear communication and timely updates, which made collaboration easy and effective. Their attention to detail and commitment to delivering a robust solution have made a significant impact, and we wouldn’t hesitate to work with them again on future projects.” – Niall Perkins – Maintenance Engineering Lead Engineer, Alstom