Find out how TP Matrix can significantly improve your fleets reliability, reduce operational costs, & improve lead times on repairs.

Class 175 Door Control Unit Overhaul – Successfully Completed!

Recent new data shows an 80% reduction in failures.

By the end of 2014, the Class 175 rolling stock based at Chester Traincare depot had been in service for 14 years and consequently, the Door Control Units (DCU’s) were experiencing an increase in failures causing reduced reliability.

On behalf of its customer TP Matrix performed a detailed Condition Assessment on a small batch of DCU’s to determine those components deemed to be at risk of failure or past their operational life expectancy.

The objective of the project was to significantly improve the fleet Reliability, reduce Repair Lead Times and reduce Operational Costs.

With limited technical information available, TP Matrix engineers used Reverse Engineering techniques to produce a detailed Technical Specification to fully understand the functionality of the product. Following this process, software was written to enable full testing of the DCUs on Automatic Test Equipment (ATE).

In total, 135 like for like (or better) components were replaced on each DCU at a rate of 4 units per week.

All work was carried out to IPC7711 & IPC610 standards.


212 units were overhauled between February 2015 and April 2017 resulting in an 80% reduction in failures compared to figures prior to the overhaul.


These are internal images of a DCU, all components were assessed for condition, signs of ageing and end of operational life expectancy.          

Click here to find out how TP Matrix can significantly improve your fleets reliabilityreduce your operationalcosts, & improve lead times on your repairs.