Imported electric screwdriver maintenance method

First, the repair tool multimeter two (analogue and digital one, analog type must be missing), diagonal pliers, needle nose pliers, iron, iron frame. Flux, tin wire, suction solder, fine sandpaper, heat-shrinkable tube, stripping pliers, slotted screwdriver (one small and medium size), Phillips screwdriver (one small and one each, plus a rubber handle screwdriver), artwork Knife.

Second, the circuit works 1, the process input (protector, micro switch) → rectifier → filter → positive and negative switch → motor → clutch 2, the normal parameters of all electronic components (1), power cord: DC resistance value, normal Values ​​approach zero; common faults: open circuit or poor contact (broken).

(2) Micro-switch: Measure the resistance value between normally open (resistance approaches infinity) and normally closed (resistance approaches zero); common fault: bad contact (black burn), key cannot be reset normally, body rupture.

(3) Protector: Measure the resistance value; Normal is zero; After slight overloading, it can reset automatically, if it is too large, it will permanently fail. In case of high temperature, it can also be disconnected (thermal protector), and it can be automatically reset after normal temperature.

(4) Rectifier bridge: Short-circuit the output (+, -) and measure the output resistance (+, -) DC resistance (about 15K).

(5) Positive and negative switches: The corresponding pin of the toggle button is a common pin, and the corresponding two buttons of the toggle button are connected.

Third, the circuit detection analysis When you get a failure of the electrical batch is unknown, it should be a preliminary test, as follows:

Set the multimeter to (×1K) zero, turn on (press) the micro switch and measure the DC resistance of the input terminal. In the positive case, it is about 15K (the digital multimeter adjusts to the measuring diode and the voltage drop is 1. 0 Left and right), this value can indicate that the electric batch circuit part works normally. Another method of testing the circuit is to short the motor pole after opening the electric batch. Under normal circumstances, the measured input DC resistance is slightly lower than the initial measurement. The maximum value (motor DC resistance is not included in the calculation).

Fourth, the motor components 1, the basic components: armature (rotor), carbon brush holder, motor front cover, bearings, magnets (stator), carbon brushes, motor pads.

(1) Armature: The most important part of an electric batch, like the "heart," the state of the armature will determine whether the electric batch can work properly. Armature is good or bad: We can learn by measuring its DC resistance. Under normal circumstances, the DC resistance (220V) between adjacent two poles of the armature commutator is about 15 ohms (depending on the manufacturer, the value is different, and the larger DC resistance is more than 20 ohms).

Damage characteristics and failure analysis: A, judging from the appearance of whether the commutator of the armature has obvious wear, and the armature with more serious wear and tear has large noise during operation: B. See if the central axis of the armature becomes smaller (Install the bearing Afterwards, when the bearing is able to rock to the right and left, the armature rotation center is unstable and the noise is large. C. There are many armature that cannot work properly because the commutator is open to two adjacent poles. When there are multiple disconnections, the motor will not start; the motor will work when one is disconnected, but the motor will stop working if the carbon brush is touching the disconnected position.

(2) Carbon brush holder: It is judged from the appearance that it is damaged and the internal carbonization (burning black).

(3) Motor front cover: It is judged from the appearance that it is damaged.

(4) Stator: Judging from the appearance to determine whether the internal disk is damaged or shifting (causing magnetic asymmetry), it is also possible to put a screwdriver into the magnet to check the magnetic size. When the magneticity is too small, it should be replaced. New magnet.

(5) Bearings: Judging from the rotating bearings, there is a stuck phenomenon. When the internal friction is strong, the motor noise is louder.

(6) Carbon brush: When the carbon brush wears to the remaining two or three millimeters, replace it with a new carbon brush (regular replacement).

(7) Gaskets: Fixed armature to prevent shaking up and down and ensure stability. The number of suitable washers; the armature will not shake up and down, and the armature can be twisted with a small force.

Fifth, the clutch 1, clutch common fault: (1). Unable to hold the screwdriver head: A drive shaft is bad, replace the drive shaft (groove becomes large, automatically fall off); (2). Missing, make up new.

2. Damage to the drive shaft: (1). The head of the driver is seriously worn on the outside and needs to be replaced; (2). Internal breakage (test method is to put the vane into the clutch, and then stuck it, use a screwdriver to twist the drive shaft, determine the sense of tripping, and determine its good or bad.)