Common faults and maintenance of the hottest 721 S

2022-10-15
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721 spectrophotometer common faults and maintenance

1 Fault phenomenon: Micro during zero adjustment; Table a is normal, and when it is adjusted by 100%,? The indication of a meter is also normal. It is only about 20 minutes after startup, and 100% indication is infinite. Restart after shutdown and repeat the above phenomenon

analysis and maintenance: this fault is obviously a soft fault in the line. The instrument consists of three parts: amplifier stabilized voltage power supply circuit, tungsten lamp stabilized voltage circuit and amplifier circuit. Zero hour? A table is normal, indicating that the amplifier circuit is normal. Therefore, it is considered to be the fault of the tungsten lamp voltage stabilizing circuit. First, check whether the pc/pbt alloy of 100% adjustment potentiometer W2 is intact when there is a lack of information. This potentiometer is a multi turn potentiometer on the control panel of the instrument brand popularity step-by-step amplifier. The resistance measured by a multimeter is continuously adjustable, indicating that the potentiometer is intact. By adjusting W2, the reference compliance of the regulated power supply can be changed, which is better than that of pet. The reference voltage is passed through the integrated operational amplifier 5g23a

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