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How to protect the tuner

Text:[Big][medium][small] time:2018/12/12 10:54:12    Views:    

High-frequency head routine maintenance and repair

       1. routine maintenance

       High-frequency head installed in the satellite TV receiver antenna, long-term rain and sun, the need for routine maintenance, the specific work are:

       ① regularly check the high-frequency head of the protective cover is damaged, fixed screws and cable connector with the receiver is loose, the joints waterproof tape is off, find the problem in a timely manner, if the joint oxidation or corrosion, to re-production. When disassembling the cable, turn off the satellite digital TV receiver, prevent the cable supply circuit from short circuit, or damage the tuner.

       ② After each rain and snow weather, it is necessary to promptly remove the high-frequency head and feed on the snow, the feeder antenna to check the feed system is water, if the water, should remove the tuner, let go Water within the feed.

       ③ self-made rain cover. With empty round plastic oil pot, the small part of the Hukou cut off, and then set the Hukou down on the high-frequency head, root Zelkowa models can choose different models of different types of oil pot. And then play three small eyes in the opening, respectively, with the antenna on the three stents fixed.

       2. Maintenance should pay attention to matters

       ① satellite TV reception is a complete receiving system, maintenance should first confirm the antenna, receiver, feeder and monitor after the failure, and then check the tuner whether there is a problem. As the tuner circuit structure and electrical performance is closely related, therefore, the high-frequency head cover is best not to lightly open, nor to allow the structure of its circuit to do any changes in order to avoid circuit mismatch or other causes High-frequency electrical performance.

       ② in the tuner in the use of a large number of micro-components, the demolition of these components more difficult. For micro-devices

       ③ low-noise amplifier used in the field-effect transistor input and output impedance is higher, the application of high voltage in the measurement of voltage to ensure accurate measurement. In the maintenance process, the field effect transistor is often damaged by electrostatic induction or electric shock, the connection field effect transistor gate electrode inspection is particularly careful; can not touch the field effect transistor, is the field effect transistor gate; When soldering the field effect transistor, be sure to turn off the soldering iron and the power supply associated with the FET.

       ④ in the maintenance, to determine a good or bad components, the general first power measurement of its corresponding voltage and determine whether the value of the problem, should not first use a multimeter to block the resistance when the components do not check the resistance value. The judge of the fault should be as accurate as possible, avoid blind welding and replacement of components, the use of maintenance instruments, workstations, maintenance personnel and tuner should be well grounded to keep the same potential.

       ⑤ in the maintenance of high-frequency circuit, pay attention to the distribution of capacitance (or parasitic capacitance) of the impact. In the high frequency circuit, the distributed capacitance of the component or circuit has become part of the circuit. The transmission characteristics of the high frequency circuit are completely different from those of the low frequency circuit. For example, in the low frequency circuit, when the level transistor is in the reverse bias state or the damage, the transmission signal is completely interrupted. In the high-frequency circuit, due to the influence of the distributed capacitance, even if the transistor is reverse or damaged, the signal may be distributed through the distributed capacitor to the next stage amplifier circuit, but the signal is much weaker than normal, take note of this, Is conducive to our judgment of the fault location.

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