Category: Electronics Troubleshooting

Today optical fiber is the infrastructure of many communication hubs. Fiber carries billions of telephone calls a day. Optical fiber makes up the backbone structure of many local area networks currently in use. In this section, we will look at planning an optical fiber installation and maintaining it once it is in place. Remember, the diode lasers (DLs) can emit radiation with a far higher energy density than sunlight, and even though you can’t see the radiation, it can easily cause blindness by retinal heating. You should always wear eye…

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Vital links of communication data flow over transmission lines daily. Phone conversations, computer data, and audio and video information all depends on the media’s ability to pass these signals wholly without any loss of quality. In this section, we will look at a problem encountered in the cabling application. Many opportunities exist today for the technician who can effectively track down and repair cabling troubles. After completing this section, you should be able to Identify popular types of cabling available for LANs and other uses. Describe crosstalk interference and give…

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The reactance is efficient and provides a large deviation. It is popular and used often in FM transmitters. Figure 1 illustrates a typical reactance modulator circuit. Refer to this figure throughout the following discussion. The circuit consist of the reactance circuit and the master oscillator. The reactance circuit operates on the master oscillator to cause its resonance frequency to shift down depending on the modulating signal being applied. The reactance circuit appears capacitive in nature to the master oscillator. In this case, the reactance looks like a variable capacitor in…

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The most likely types of FM radio a technician will be called to service are an automotive mobile, a fixed base station, or a hand-held portable. Either the mobile or the fixed base station can have power outputs as high as 150 W. Some of these transmitters can be damaged if not operated into the proper load impedance, usually 50-ohm. Some contain automatic circuitry to shut the transmitter off it is not connected to a proper load. Dummy loads are made for this purpose, so make sure you have one…

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If the system is completely dead, that is nothing happens in the system, you should immediately suspect the power supply. This is one part of any system where the average technician can often find and repair a problem. Any system is powered by battery or a transformer-rectifier supply connected to the 220-V lines. Batteries usually power portable system. A 9-V battery is most common. To check its output voltage, turn the system on (to load the battery) and measure the battery’s terminal voltage. If it is significantly below 9V, perhaps…

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In this section we are going to analyze and troubleshoot the AM converter circuit. the converter, also known as autodyne circuit, is a combination of the local oscillator and the mixer in a single stage. We are also going to discuss the power supply and audio amplifier problems in this section Upon completing this section, you should be able to Troubleshoot an AM converter circuit Identify an open input circuit Identify a dead or intermittent local oscillator circuit Identify causes for a dead and intermittent local oscillator Troubleshoot the receiver’s…

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TV and FM antenna installation practices will be preferred to throughout this discussion. Installing TV and FM antennas portrays fairly standard practices that should be followed when doing any kind of communications antennas installation. Never neglect safety. Standard operation procedure should always make safety first on the list of things to do. Locate power lines, telephone lines, and obstacles that could interface with the installation or present a hazard to the installers. A tower structure would require a concrete base as the supporting structure. Guy wires need room for proper…

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