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Common interphone fault diagnosis and troubleshooting


  In recent years, the utilization rate of walkie-talkies in various industries in China is increasing. Professional users such as public security, armed police and forest, construction sites, property, security guards and civilian amateurs are being used in an increasingly wide range.The following author more than ten years of experience in the maintenance of some daily use of the most common fault and the correct way to use some simple introduction for walkie-talkie users reference.

  A.Antenna: antenna is the most critical component of the whole transceiver. Once the antenna fails or is defective, it will affect the transceiver communication effect.Users in the use of often antenna with your hands to drive the intercom, more serious is that artists in antenna tail shaking interphone.Due to the launch of the inward and outward mouth machine is high frequency receiving antennas, often use is professional, TNC, BNC, SMA interface at this time due to the mechanical strength of the antenna, antenna skin fall off over time, the antenna fracture, needle needle or antenna interface is smaller, serious when they make the antenna and the circuit connection between needle desoldering.At this time, the standing wave transmitted by the machine has become larger. Under the circumstance of continuous operation, some machines with poor protection measures will produce faults such as power tube, power amplifier module burning loss or power resistance burning out, and users will generally send them for repair under the condition that they cannot accept the word.The proposal usually USES when the attention grasps the correct use method, often checks the antenna, the antenna base connection is reliable, whether has the dirt, the antenna outward appearance is damaged, if has the damage, the proposal replaces the same model antenna, the antenna base.

  2.Battery: battery is the source of power supply.Because the radio transmitter current is large, disposable alkaline batteries are less used.Most walkie-talkies are rechargeable nickel-cadmium, nickel-hydrogen, or lithium-ion batteries.Often can have a user to put forward battery use time is not long enough, just charge electricity (PTT) did not press a few times to have no electricity, in addition to individual operator to use inferior electric cell, affect outside normal use, correct use method is to be able to extend the use time of battery and service life.Investigation and inquiry of users found that some users will put in the charger when they want to use it for a period of time, pick up and use, no regular charge and discharge.Due to the memory characteristics of nickel-cadmium batteries, the phenomenon of insufficient charge will be generated.There are also some users who do not use the machine for a long time with the battery on the charging seat for a long time.We should know that many simple chargers on the market are not full of tips and protection circuit, so a long time will form a battery overcharge, serious battery will be scrapped.Lithium ion battery users are usually equipped with professional lithium charger, but it is recommended that users use up each charging cycle before recharging.Although lithium battery has no memory characteristics, its capacity will be greatly reduced after two to three hundred charging and discharging cycles.In addition, there are some machines due to different operating environment, or battery quality problems, resulting in leakage, the machine and battery contacts will produce oxidation, corrosion.Lead to poor contact between the battery and the machine.This phenomenon can be generally seen from the surface, light can be used to scrape clean blade, serious corrosion of the recommended battery scrap, machine repair.

  3.PTT(launching key) : the launching key is the most frequently used part in daily use. In some machines sent for repair, it is found that some of the machines are aging or damaged, affecting the normal use.Some affect the circuit board of the key, the button contact is bad, the key failure and other faults, the best maintenance with the same model of the original device.

  Four.Power switch, static manic potentiometer, stepping potentiometer: the power switch in the walkie-talkie is generally integrated with the volume potentiometer. Some low-end machines have problems with the quality of components, which can switch the power supply, but have problems with the volume adjustment.It is recommended to replace the same type of good devices.Static manic potentiometer repeatedly adjust the opportunity is less, but need to work in a particular location, some users are afraid of adjustment trouble, simply use glue to stick to death, so in the future maintenance buried hidden trouble.Stepper potentiometer is used to convert channels and manual programming, good potentiometer feel very good, rotation step between clear, do not have a smooth feeling.Some machines will damage the potentiometer shaft, so that it can not change the channel and programming, repair can only be replaced with new parts.At present, some machines use the button switch, this type of machine should pay attention to the use of a long time, the conductivity change.Sometimes do not cause the boot, or repeatedly press several times to boot, maintenance should be considered to clean the keyboard and circuit board.

  Five.Conductive keyboard: most walkie-talkies are equipped with DTMF keyboard and programming keys. If the keyboard is damaged, greasy, some keys fall off, and mice and cockroaches are bitten in the machine sent for repair.Such faults only need to be cleaned or renewed.

  Six.Loudspeaker (horn) : loudspeaker is a key part of walkie-talkie, some users like to turn up the volume to the maximum, some machine audio amplifier and bar match is not designed very well will burn it.There are some special environment users, with a period of time, the sound is getting smaller and smaller, maintenance found in the sound film on the absorption of a lot of iron powder, iron powder thoroughly clean generally can restore the original.Seven.Audio components (headset) : some users will use earphones and other external accessories due to the working relationship, audio plug generally rely on special plug and socket connection, over time will produce bad contact with the socket or take off welding, because the socket is generally with a dynamic break point, at this time will produce bad fault.It is recommended to replace good socket during maintenance.Eight.Machine clamp (back clamp) : machine clamp is the necessary accessory of walkie-talkie.When users use there will be screw off phenomenon, some users will find a screw to screw on regardless of length, there are self-tapping screws.Some machine back clamp screw hole is through hole type, screw too long will damage the circuit board, serious machine will be scrapped.Walkie-talkie back clamps are generally marked with screw size, such as: M3X5mm means screw diameter of 3 mm, length of 5mm, must be required to use back clamps screw.Most of the above introduction is the appearance and mechanical failure of walkie-talkie.The most common mechanical fault is the machine drop fault, the general drop fault will sometimes do not turn on, or can start to launch but do not receive, or receive close to the phenomenon, inspection machine appearance, LCD (liquid crystal display) is damaged, LCD damage is generally replaced with the same type of LCD.After the drop caused by not starting (starting generally prompted sound) generally first check whether the power supply is normal, whether there is a voltage CPU crystal foot, there is a voltage using an oscilloscope to detect whether the vibration, if not vibration, general damage to the crystal, replace the crystal.Also, if the receiving fault is caused by drop, please check the if dipole crystal and some relevant filters of the receiving channel.Here by the way to mention the water or rain caused by the fault, the user encountered this kind of problem, must be shut down at the first time, remove the battery, dry with dry cloth dry water, blow dry with a hair dryer, serious should be timely please professionals to remove the machine, don't do the rest.Because the circuit board meets the water the fault repair rate is low, the scrap rate is high.