Repairing a Kenwood Chef A901D That Emits a Burning Smell

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An old A901D started emitting smoke and a strong smell while running. Failing components in the motor control circuit were causing the smoke. Components replaced were a BTA08-600CW triac, a 150nF block capacitor, a 470nF block capacitor and a 150 kOhm resistor. All components can be purchased for a few pennies.

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Flip the machine upside down, so that the bottom is facing up.

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Remove the screw that holds the cable connector to the motor cover.

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Open the pedestal.

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Take out the motor cover. It is held under the axle of the pedestal.

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The motor control electronics are now exposed. For other models, the control board may look different. But you can often recognize the defective capacitor(s). Replace them and any additional defective resistors (if any). The triac is under a lot of stress and brakes easily. Replace it if necessary. The components listed are all very cheap.

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Here is a picture of the two oil paper capacitors. They break more easily, the case cracks. Replace them with more modern MKP types.

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Unscrew the two speed adjustment screws. Remove the springs and the screw retention clamps.

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Remove the thermal fuse from its holder.

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In the first picture, three of the four components were already desoldered. Unscrew the triac. Note the thermal compound on the heatsink of the triac. Thermal paste will be applied to the new triac later.

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The thermal fuse is inserted, the power switch is not soldered yet.

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Everything is completed and ready to be reassembled. The on / off switch is soldered, the adjusting screws are screwed in and the circuit board is attached to the case with both screws.

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Adjusting of the speed control after repair: