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Once it is determined that the remote control receiver circuit is not working properly, the fault can be distinguished from which part of the circuit by the following method, that is, it is from the high-amplification, ultra-re-upgrade circuit or the amplification and shaping circuit.

① When checking amplifying and shaping circuits, the input/output point of the signal is the key point to find the fault. The specific method is to use the remote control to transmit the signal, and use the oscilloscope to observe whether there is signal input in the amplification and shaping circuit (such as the ⑤ pin of LM385F). Circuit; if the signal is not detected, the fault is before the super-up circuit: check the amplifier and reshaping circuit, you can measure the pin voltage of LM358 and compare it with the normal value. If it is not normal, the integrated circuit itself is mostly damaged.

② For the overhaul of the super-re-up circuit, check the DC voltage of the transistor first. If it is abnormal, check the DC bias circuit or the transistor itself. After the DC bias voltage is normal, check the AC feedback circuit again. It is best to use the replacement method to check the patch capacitor.

③For the maintenance of high-frequency amplifier circuits, the method of checking the DC operating point of the high-frequency amplifier tube and then the coupling components is also adopted. Generally, it is not difficult to find the faulty components.

Because the remote control receiver works under the condition of low voltage and small current, there will be no failure of burning the circuit board, and the damage rate of transistors and integrated circuits is not large. The highest failure rate is the deviation of the receiving frequency, which is mostly caused by the water ingress or the damp on the circuit board, which makes the super-re-lift circuit stop oscillating. Do more cleaning and damp-driving work, measure more voltage (waveform), and remove components as little as possible.

The receiver for the automobile anti-theft system, whether it is an adjustable inductance or a capacitance adjustment, and whether it is a discrete straight plug-in unit or a SMD device or a hybrid method (SMD for resistance-capacitance components, straight plug-in units for transistors, integrated circuits, and electrolytic capacitors) ), they are almost completely interchangeable, as long as you find the correspondence between GND (ground), +V (power positive), and OUT (signal output), and readjust the receiving frequency of the receiver.