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Obsolescence-Resilient Repair of Electrostar Fleet DCUs

Project Summary

383 obsolete Electrostar Door Control Units (DCUs) repaired in 2024 – extending asset life and avoiding costly fleet-wide replacement.

Developed a bespoke automated test system – enabling accurate fault diagnosis, comprehensive functional testing and faster turnaround times.

Achieved zero units deemed unrepairable due to obsolescence – through proactive component replacement and ongoing obsolescence management.

Background

A large number of Alstom’s legacy Electrostar fleets have long relied on a specific model of Door Control Unit (DCU), which recently entered obsolescence as declared by the OEM. Alstom required a repair partner who could not only restore performance of the DCUs but do so with long-term sustainability and cost efficiency in mind.

Enter TP Matrix – specialists in electronic repair and overhaul within the rail sector. With deep experience in obsolescence management and complex systems testing, TP Matrix partnered with Alstom to develop a proactive, scalable repair solution for the entire fleet.

Client challenges

The task involved two primary challenges:

  • Restore failed DCUs to full operational condition, post in-service failure
  • Navigate and mitigate obsolescence risks, ensuring repairability over time

With over 6000 units in service and OEM replacements no longer an option, the economic implications of a full system replacement were significant – potentially running into millions of pounds across the fleet. TP Matrix’s repair-first strategy offered a compelling alternative.

Automated testing from day one

From the outset, TP Matrix invested in developing a bespoke automatic test box to simulate full DCU functionality. This rig enabled:

End-to-end functional testing under load

Precise fault isolation

Verification of repairs with repeatable accuracy

This upfront engineering effort ensured every repaired unit could be confidently returned to service, meeting both safety and performance standards. It also streamlined turnaround times, reducing overall downtime for the fleet.

The solution

TP Matrix receives each DCU following in-service failure. Together with Alstom, they defined a pre-agreed list of components known to:

Exhibit high failure rates

Be at risk of obsolescence

383 DCUs repaired

0 units unrepairable due to obsolescence

Results: Low Risk, High ROI

Repairing rather than replacing the Electrostar DCUs has already delivered substantial cost savings for Alstom. By avoiding the capital expense of a full fleet retrofit, Alstom has:

Extended the service life of its DCUs

Reduced waste and environmental impact
Preserved budget flexibility for other fleet priorities

Meanwhile, TP Matrix’s methodology ensures minimal disruption, maximum reliability, and a low long-term obsolescence risk.

Engineering insight: Agile component management

The predefined replacement list has proven highly effective, addressing the majority of issues found across units. Only one component has since become obsolete. TP Matrix sourced a like-for-like alternative, secured full engineering change approval, and integrated it into the mandatory change list without affecting delivery schedules.

All other components replaced during repairs have shown no obsolescence issues to date. Furthermore, TP Matrix actively monitors emerging trends in component failures and adapts the repair scope in real time.

Client feedback