How to analyze whether the normal work of the remote control receiver

(1) identify the quality of the remote control receiver

If the distance of remote control anti-theft system too close or remote control does not work, should consider whether the remote control receiver circuit failure. To determine whether the normal work of the remote control receiver, commonly used methods are as follows.

The spectrum analyzer receiving antenna near the receiver, to the alarm system (or receiver) power, in 200 ~ 400MHz band should be observed in wavy (adjustable capacitive) or gaseous (adjustable) spectrum waveform. Such as spectrum analyzer screen without any reaction, illustrate the receiver circuit fault.

Using the remote control signal, using the oscilloscope observation receiver output (out), decoding circuit input due to pulse signal output. Due to the transmitted data signal, the waveform of pulse width of different combinations, such as waveform is not normal or undetectable waveform, illustrate the remote control receiver part has fault.

The observation of the remote control receiver signal output end of the oscilloscope, with the antenna metal touch remote control receiver input end, clutter reaction oscilloscope should be more strong, otherwise the receiver part of a fault.

To use the remote control signal voltage, DC voltage with a multimeter measuring signal output end of the block, when press the remote control button, the voltage should change its output, such as no response, illustrate the receiver circuit fault.

(2) to determine the fault location of the remote control receiver

Once the remote control receiver circuit does not work properly, you can according to the following method to distinguish the fault from what part of the circuit, which is from high level, then put super upgrading circuit or amplified, shaping circuit.

Check amplifier, shaping circuit, input / output signal is the key point to find fault. The specific method is to use the remote control signal, using the oscilloscope observation amplifier, shaping circuit has no signal input (such as lm385f, 5 feet) as signal waveform, that of the super high rise circuit normal discharge circuit, amplifier, shaping circuit, fault; such as undetectable signal, then the fault circuit on the rise again before: the amplification, shaping circuit inspection, can pin voltage measurement of lm358, and the normal control, if not normal, for integrated circuit damage.

The super rise circuit maintenance, can check the DC voltage of the transistor, if not normal, check the DC bias circuit or transistor itself. The DC bias voltage is normal, check the AC feedback circuit, the chip capacitor is best to use the replacement method to check.

The high frequency amplifier circuit maintenance, also take the first inspection method inspection pipe coupling element high DC operating point, is generally not difficult to find the fault components.

The highest failure rate is receiving frequency offset, mostly because of water or damp circuit board circuit to stop oscillation caused by super rise again. The receiver car anti-theft system, whether it is adjustable or adjustable capacitive type, whether discrete or plug-in components is straight or mixed, among them almost completely interchangeable, as long as you find the GND (ground), +v (power out (positive), signal output end) correspondence, reception you can re adjust the receiver and frequency.