How low are the voltages? ABB specs for incoming voltage are -15% to +10%. The ideal voltage to the power supply is 55VAC 3-ph and 262VAC 3-ph going to contactor K1.
The transformer is tapped for different incoming voltages, make sure the incoming voltage and the transformer jumpers match. If you're not sure, post the transformer part # and what the incoming voltage is. Page 363 (diagram sheet 12) in the previously mentioned manual gives the transformer jumpers needed.
To get an answer in general regarding aftermarket controllers, I would start a new post in the General Discussion of Industrial Robots Only. If it's specific to only ABB, then start a new one here in the ABB forum.