The Nintendo monitor needs an inverter board when the monitor is used with modern conversion kit games. For using the monitor with a Donkey Kong board you want to use the "Non-Inverted" connector. As for the darkness issue, if you have already installed a cap kit then try adjusting the "sub-bright" control on the main monitor board and if that doesn't help then try the "screen" control on the flyback. Then if after all this it's still too dark then you may have to have the picture tube 'rejuvenated' at a tv repair shop.