In our daily lives, people are connected to each other by telephone and cell phone, and it is amazing to think about how many people have come to us, how many thousands of miles from here, and how many people can talk at once. And the magic of the phone, and not much more, but now that the phone's out of order, let's take a look at the looser, unlined, telephones, frequent failure analysis and removal。
1. Host does not match the password
One of the poor reception and transmission circuits could lead to a failure to match the password, but there are more frequent reasons for failure to match the code, usually caused by voltage-controlled voltage shifts. The normal receiving, launching and voltage control voltage is typically (2. 8±0. 1) v, which can be fine-tuned to the magnetic core of the circle if the voltage control is deflected。
2. Host not accepted
In case of such failure, it is advisable to follow the transmission path with a high-frequency oscillator or a uhf mpv. First, we use oscilloscopes to observe whether there is a radio frequency signal input, and if we do not check if the transistor is defective, if the magnetic core is in discomfort, if there is no welding. If normal, the 1o. 7 mhz output waveform is observed. If the output is normal without input, it is mostly 10. 7 mhz ceramic filters. It then observed an input shape without 455 kthz. If no, check the normal operation of 1o245 mhz clock circuits. And the 455 mhz ceramic filter itself is not bad。
3. Host not launchable
Focus on checking whether the radio frequency oscillator is oscillated. If no change is likely to cause damage to the transistor phase, a replacement of the tube may be possible, and the normal voltage of the v pressure should be measured (2. 8±0). If normal, check if incentive, performance is normal and if observed with a oscillator, the performance waveform should be larger than the incentive level。
Four, sideline is off
If the phone is able to make an internal call, and the secondary is unable to take off, it's malfunctioning on the outside of the cmu switch to control the output end to the external power switch. You can press the secondary key and control the output end with an outer-wire switch to measure the host mcu using a tensile meter, voltage block, if the high level is normal; if the low level of power is to be checked for the cmu chip circuit. If the outer switch controls the output end level, check the power switch, driver and external connection。
Five, side
Handheld calls are normal, indicating that the telephone circuits comprising the call chip are working properly and that failure is limited to receiving and transmitting channels. It usually pulls the dc9v plug and then plugs it in, and if the microprocessor fails, it's normal. If the adjunct is able to dial, no call is possible. First, check whether or not the mainframe cable telephones are available ... If they are not available, the failure may occur between the telephonic transmitter and the negative transistor; if you are able to make a call, it is clear that the main call circuit is working properly and that the failure is the transmission voice double circuit before the secondary transmitter to fm oscillation。
The overhaul of the mainframe should be preceded by the lifting of the mainframe handles and a blow-out of the transmitter, with the oscilloscope being used to test the circuit between the transmitter and the negative transistor. When the auxiliary machine is repaired, it is first placed on the switchboard, breathes into the transmitter, uses the oscillator to detect the message end, and the pressure controller input end should be shown. If a certain level of circuit is not shown, the failure is in that level of circuit. Particular attention should be paid to the high electrical level at which the silent switch control end should be in a state of shut-off, otherwise the cmu chip should be checked。
6. Reduction in inter-branch communication distance
First, the charger's voltage is checked for adequacy and interference with the surrounding environment is excluded. Mainly check the reception sensitivity of the main and secondary aircraft. Hf fm signals can be entered from the antenna port and wave shapes of the output end of the enumerator can be observed with oscillators, most of which are due to failure of 455 khz ceramic filters. Communication distances are reduced due to poor quality of components, unstable parameters or the presence of hidden short circuits and openings in circuits. It can be used to beat and knock on the presence of welds, while subsequent instrumentation should not blindly adjust the lc circuits without instrument monitoring to avoid the difficulty of recovering from a breakdown。
In our normal lives, every product has a day of failure, so don't panic when the phone is down, first analyze how it's broken, and then remove the possibility and then repair. It's best to fix this yourself. Of course, you can give it to a professional telephone repairer, or you can buy a new loose-lined phone. These are the more common malfunctions of loose-lined telephones and why。
