The desktop centrifuge is a machine that uses centrifugal force to separate the components in the mixture of liquid and solid particles or liquid and liquid. The product has the advantages of stable performance, flexible use, high reliability, and easy maintenance. Table-top centrifuges will produce certain failures during use. Today we will mainly introduce the problems of bench-top centrifuges and their solutions, hoping to help users better apply products.
Example 1. The motor speed slows down and the brush emits a large spark
Analysis and maintenance: This fault is caused by dirt between the motor carbon brush and the commutator or the elastic force of the carbon brush spring is reduced, so that the carbon brush and the commutator are in poor contact. Disassemble the machine, unscrew the cover of the brush box, and take out the carbon brush with the spring. First, clean the dirt on the spring, carbon brush and commutator with absolute alcohol. If the front of the carbon brush is broken, use a file Sandpaper grinds the carbon brush into a smooth arc contact surface to make it fit well with the round commutator. Then increase the elastic force of the spring appropriately. After the above treatment, the fault can generally be eliminated.
Example 2. When the desktop centrifuge is working, it emits very loud vibration noise
Analysis and maintenance: The reasons and solutions that cause vibration and noise when the centrifuge is working are:
(1) The mechanical parts and fasteners such as the screw on the upper end of the rotating shaft or the damping spring fixing screw on the base are loose, just tighten it again.
(2) The motor shaft is bent or the bearing is worn. If the motor shaft is bent, it can be solved by repairing and correcting it. If it is serious, it should be replaced; if the gap increases after the bearing is worn, a gasket can be added to the shaft to solve it, and it should be replaced when it is serious.
(3) The elastic force of the three damping springs on the machine base is reduced or broken, which makes the turntable shake more when it rotates. Just replace the shock-absorbing spring.
(4) The outer cover is deformed or incorrectly positioned. Just repair, adjust and calibrate the outer cover, and install the outer cover firmly.
(5) There are foreign objects such as broken glass pieces in the test tube sleeve, which make the load out of balance. Before each use, check whether there are other foreign objects in each test tube sleeve. If there is, it must be removed before use.
(6) The test tube sleeve does not match the machine. The test tube cover is precisely matched by the manufacturer for the machine. The test tube cover of different types of centrifuges cannot be changed at will. Otherwise, vibration and noise will be generated when the centrifuge is working.
Example 3. Power on, the motor does not rotate
Analysis and maintenance: During maintenance, first observe whether the work indicator is on. If it does not light up, the cause of the fault is that the power cord, power switch K1, and other input circuits are bad, but the primary coil of the power transformer Bl is generally open. If B1 is a non-burning open circuit, you can use a multimeter to measure the on-off of each tap to find the open circuit (breaking point), as long as the breaking point is reconnected and welded firmly. If B1 is a burnt open circuit, rewind or replace it. If the work indicator light is on, check the speed control switch K2, the timer and the motor for damage. First measure whether there is 220V voltage at both ends of the motor; if not, it means that the timer and K2 are disconnected. For K2 inspection, a knife can be used to scrape off the oxide on the contact surface. Then adjust the initial position of the correction contact shrapnel to make it contact well. For the inspection of the timer, the timer can be removed and disassembled, and its contacts can be cleaned, adjusted and corrected. If the mainspring or cam is damaged, the timer should be replaced: if there is 220V voltage across the motor, then The motor is faulty. Listen to the motor for a "buzzing" sound. If there is, the stator and rotor of the motor are stuck by foreign objects. Just disassemble the motor and remove the foreign objects between the rotor and stator; if there is no "buzzing" sound, yes. If the winding is open, it can be rewinded or replaced with a new motor.
