An electronic apparatus comprising a housing and, disposed within the housing: a power supply unit (200,318,319) arranged to receive electrical power from an external source and supply electrical power to components of the electronic apparatus; a heat source; temperature sensing means and humidity sensing means; characterised in that: the temperature and humidity sensing means comprise a plurality of temperature and humidity sensors in a plurality of locations within the housing, at least one of said temperature and/or humidity sensors being provided in a path of internal air flow: the electronic apparatus further comprises: a power controller arranged, in use, to control the power supply unit (200,318,319); and an electronic processor arranged to receive power from the power supply unit (200,318,319) and to carry out functions of the electronic apparatus: wherein, upon startup of the electronic apparatus, the power controller is arranged to: receive temperature and humidity data from the temperature and humidity sensing means; process the received temperature and humidity data to indicate a current dew point within the housing; compare the current dew point with current location temperatures at locations within the housing; if a current location temperature is at or below the current dew point, activate the heat source to raise the temperature within the housing; and only if the current location temperatures are above the current dew point, supply electrical power from the power supply unit (200,318,319) to the electronic processor. a power supply unit (200,318,319) arranged to receive electrical power from an external source and supply electrical power to components of the electronic apparatus; a heat source; temperature sensing means and humidity sensing means; characterised in that: the temperature and humidity sensing means comprise a plurality of temperature and humidity sensors in a plurality of locations within the housing, at least one of said temperature and/or humidity sensors being provided in a path of internal air flow: the electronic apparatus further comprises: a power controller arranged, in use, to control the power supply unit (200,318,319); and an electronic processor arranged to receive power from the power supply unit (200,318,319) and to carry out functions of the electronic apparatus: wherein, upon startup of the electronic apparatus, the power controller is arranged to: receive temperature and humidity data from the temperature and humidity sensing means; process the received temperature and humidity data to indicate a current dew point within the housing; compare the current dew point with current location temperatures at locations within the housing; if a current location temperature is at or below the current dew point, activate the heat source to raise the temperature within the housing; and only if the current location temperatures are above the current dew point, supply electrical power from the power supply unit (200,318,319) to the electronic processor. a power controller arranged, in use, to control the power supply unit (200,318,319); and an electronic processor arranged to receive power from the power supply unit (200,318,319) and to carry out functions of the electronic apparatus: wherein, upon startup of the electronic apparatus, the power controller is arranged to: receive temperature and humidity data from the temperature and humidity sensing means; process the received temperature and humidity data to indicate a current dew point within the housing; compare the current dew point with current location temperatures at locations within the housing; if a current location temperature is at or below the current dew point, activate the heat source to raise the temperature within the housing; and only if the current location temperatures are above the current dew point, supply electrical power from the power supply unit (200,318,319) to the electronic processor. receive temperature and humidity data from the temperature and humidity sensing means; process the received temperature and humidity data to indicate a current dew point within the housing; compare the current dew point with current location temperatures at locations within the housing; if a current location temperature is at or below the current dew point, activate the heat source to raise the temperature within the housing; and only if the current location temperatures are above the current dew point, supply electrical power from the power supply unit (200,318,319) to the electronic processor.