The base power unit contains the motor and electrical speed control switch. The motor used is a series or universal type because it will deliver the high speed needed for complete blending or liquidizing of the material placed in the container. Operating speeds may be as high as 16,000 rpm. Most blender power units are accessible for service by removing the base plate. This will expose the power cord connections and the brush end of the motor for electrical testing. The control switch is mounted on a front panel and in some cases the motor may have to be removed in order to make the switch accessible for test or replacement. The greatest difference between blenders is in the method of motor speed control. They may have rotary switches, toggle switches or push button switches, each requiring a different electrical circuit.
Electrical testing is done with a volt-ohmmeter. This device is used to deter-mine if the voltage is available to the motor. The ohmmeter portion will indicate the condition of the switch and the electrical windings of the motor. Before making any electrical tests, try to turn the motor by hand, using your fingers to turn the drive lug. If it doesn’t turn, the armature is frozen. Clean the motor bearings and lubricate them. If this doesn’t solve the problem, continue trouble-shooting. When using the volt meter section of the volt-ohmmeter, the blender must be plugged into a wall socket. The meter switch should be set at the 150-volt AC position. During the tests a line voltage of about 115 volts should be obtained when the leads are connected to: (1) the wall socket no voltage indicates a defective socket; (2) the connection of the power cord to the switch and motor no voltage indicates a defective cord; (3) the motor connection of the power cord and the other side of the switch, with the switch turned on, no voltage indicates a defective switch. If the voltage is available up to the motor and the motor does not operate, it is probably defective.
Each electrical part can be tested individually with the ohmmeter. Follow the instructions with the meter to change over resistance readings. Turn the switch of the meter to the R x 1 position. Caution: unplug the cord from the wall outlet before making these continuity tests. The line cord should show continuity (zero ohms) from each terminal on its plug to the end of its wire. The switch should show continuity from terminal to terminal when it is on and no continuity (infinity, shown by a sideways figure 8 on the dial) when it is off. The motor should show a resistance reading. No continuity would indicate it to be burned out. Any defective part should be replaced. Switches and motors of blenders are not ordinarily repairable. The most commonly used tools are either a standard or Phillips screwdriver. A nut driver may be needed in some models to remove the switch or disassemble the motor. Although defective parts will have to be replaced, an exception could be a loose or broken wire or a power cord that is broken at the plug end or at the point where it is clamped under the strain relief. The loose or broken wire can be resoldered and the power cord can be shortened and reconnected.
Parts should be available from a dealer who handles the particular make you have. If the dealer does not have the parts or says that he cannot get them, try the manufacturer of the blender. Sources are usually listed in the yellow pages of your telephone book under “Electric Appliances Small Repairing.” There are very few mail order parts outlets that might have all the special parts for the many different blenders in use. There are some very good small motor repair specialists who could repair or replace defective motors or any parts. These specialists are usually located in a major metropolitan area, listed in the yellow pages under “Electric Motors Dealers Repairing,” When reassembling the unit make certain some good light grade of oil is applied sparingly to the shaft and bearing. Be sure the armature turns freely by hand before applying power.
A word of caution before getting too involved in a major repair, consider the cost of a new blender. Also consider the age of the unit requiring service and the potential cost of parts.