Cuisinart DCC 1200 Teardown and Power Module Schematic

Tore apart and analyzed a broken cuisinart coffee maker. Pictures after the break.

Took the base off using screwdrivers (needed a Torx driver).

The heater measured in at around 14 ohms

Interesting that there was an overhand knot tied in the mains cord, presumably for strain relief.

There's a connector from the power module up to the front panel/controller. I had trouble getting at the controller PCB without smashing the plastic apart, looks like there are a lot of snap-together bits on the top half. (Taped the connector so I would have easy access to it.

Traces colorized to show some of the planes - the circuits appear to operate using the negative half-phase of AC mains with the mains neutral line acting as the source (high potential) and the "hot" mains as the sink (low potential).

Red = AC mains in

Blue = AC neutral

Yellow = Zener Reference Return (serves as ground for most of the circuitry on this board)

I determined most of the schematic for the power module. Some of the surface mount resistor values were pretty tough to see (don't have a microscope handy) so the values could be off.

(Click schematic for larger version)

A rough simulation confirmed the zener establishes a reference DC voltage from the AC mains. I measured it right at 5V on this board (simulation below used a different 6.2V Zener diode for a slightly different bias point). The simulation below doesn't use the correct reference designators (was too lazy to update) but the above schematic does.