Technical Overview - Fisher & Paykel DishDrawer DD60 Service Manual

4.1 Chassis
The DishDrawer chassis is one complete assembly composed of 5 steel metal components locked
together by a proprietary riveting process. The chassis exterior is made of a lacquered electro-
galvanised material.
4.2 Drawer Fronts
Prefinished drawer fronts are formed from steel blanks. The drawer fronts are attached to the tub by
means of formed hooks and two square pins that are inserted through either side of the tub.
4.3 Electronics
The electronics system is made up of 2 separate boards, the wash controller and the motor controller.
Each tub has 1 wash controller, and in the base of the product is a motor controller, which both tub
wash controllers are connected to.
The wash controller is the main control. This board controls the wash program selected on the LED
display. It monitors the water temperature, tells the motor controller to activate the lid actuators, wash
motor and fill valves as required. The wash controller also controls the drying fan, detergent dispenser
and water softener (if fitted).
The display LED is also connected to the wash controller, and depending on model, may control the tub
it is connected to, or control both upper and lower tubs. There are no secondary touch switches shown
on the tub. All cycles are selected through the display.
The power supply to the wash controller is isolated, but it is still recommended that the power be
disconnected from the main supply before any servicing is carried out.
The motor controller is situated in the base of the chassis, and is connected to the 2 wash controllers
by way of a harness.
The motor controller controls the wash motors, fill valves, lid motors and elements on both tubs. It has
two 24V rails, one of the 24V power supplies is used for the loads that the motor controller runs, this
not
supply is isolated and must be treated as live at all times.
The other 24V supply is isolated and is fed up to the wash controllers to allow them to run their loads.
The motor controller requires several conditions to be met before it will run certain loads. For example,
in order to prevent accidental flooding it won't run the motor in the wash direction unless the tub is
closed and the lids are down.
In addition, except in diagnostic mode, it won't turn on an element unless the wash motor has prime,
which requires the tub to be closed and the lid to be down.
Unlike previous versions of the DishDrawer, the element is now switched by a double pole relay. This
protects against certain element fault conditions which can occur. The element is further protected by
two non resettable thermal limiters.
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4 TECHNICAL OVERVIEW