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The converter in the 8 function controller is just a bridge rectifier made with 4 diodes. You're unlikely to damage the lights by removing it but you can get some pretty impressive flicker if you remove it and still try to use the original AC plugpack.
If you've left the 8 function controller in place when trying to use the DC supplies then this may also not work. The AC input is often used for timing purposes within the 8 function controller.