In the run up to a large production order, a high tech aerospace manufacturing facility suffered a breakdown on a critical machine tool. The main Fanuc spindle amplifier was blowing fuses. Typically the breakdown happened during a night shift. The engineering team on site realized this was not going to be a quick fix and removed the amplifier and its companion power supply unit. The shift supervisor knowing the skills we have at Fletcher Moorland phoned our 24 Hour manned workshops and asked for the units to be collected and repaired on an emergency service basis. Once back at our works both units were assessed and stripped down. The fault was located to a blown power device on the spindle amplifier, this had also caused a burn up on the controller PCB. The PSU was operational but in a poor condition. As these units work as a pair, it was our recommendation that the PSU be overhauled at the same time. Both units were fully cleaned to remove the oil residue that had contaminated the PCB’s and chassis. A new power block and driver PCB were taken from our stores and fitted to the amplifier. As standard all electrolytic capacitors were replaced with 105ºC low ESR types, all opto-isolators were replaced and the relays and cooling fans were replaced. The units were reassembled and checked for operation on our Fanuc Spindle Test Rig. Once we were satisfied with the results of the test, both units were delivered back to our customer to enable them to be fitted in time for production start up at the beginning of the morning shift.