It soon became obvious once the lid was off where the magic smoke had come from and where the problem may lie.

The controller is full of the dreaded ‘Rifa’ capacitors, these are paper capacitors with resin dipped casing that breaks down with heat and age allowing moisture in. Once this happens a bang soon follows.

You can see the 0.1uF capacitor in the centre of the image has split open horizontally and in the background a resistor has also burnt.