【 Weak current College 】 TV appear several bar causes and elimination 】

Power interference to TV screens appear white, black, or black and white horizontal stripes of several of its stripes or wide or narrow, slow down, or scroll. If the interference source frequency is 50 Hz, resulting in pictures on a cross-road, if the frequency is 100HZ interference sources, to produce the picture two crossing. Power interference is a cable TV network system in common a fault, the fault is in the picture on the up and down the white line road, the interference of light, white mobile thin horizontal lines, damage to TV pictures, look at a low frequency band on television, the high frequency band is not obvious, dark field see clear, bright field of view was not obvious to the average user doesn't care about, the more serious when a power interruption, white thin line broadening into a bar and even images are distorted, field is not synchronized, and down beat, people cannot view, power interruption causes one of the following circumstances:
1, the line appears down the supply voltage is low, the use of electrical equipment is not working properly; first check electric AC voltage is low, less than A: AC will make some 180V, using equipment is not working, producing AC power interference; B: If you choose the feeds amplifier 60V, multilevel drop around after to 36V, amplifier supply voltage low, generating alternating current
2. equipment in power supply voltage, filtering performance is not good, ripple coefficient. If the amplifier power supply filter capacitor failure, damage to the circuit in a large ripple, these ripple will appear on the TV screen to move up and down the line road; the horizontal road under capacitor failure and damage, which is manifested in the screen's horizontal road weight difference between sparse and dense.
3, the contact resistance of poor performance with large or devices; 220V/5A power socket or power head oxidation resistance is bad, the increase in the use of internal power supply line, Zener diodes wires power resistance increase, causing the power interruption.
4, external AC cuanru: for the first three conditions, measured, the use of alternative replacement methods, within a short period of time can be repaired, to solve the problem. While external AC channels cuanru, find it extremely difficult to replace devices see results, segmentation fault signal check, cable TV user views, a long time to the detriment of the Organization's reputation, through years of maintenance summary, home-made a with capacitive isolation line of devices — "double Dragon separated with", although it is not possible to fully resolved, but can inhibit AC power interference, easing the user relationship so that the maintenance procedure become simple and quick. External AC channeling into many of the channels, through actual maintenance summary cause is generally divided into the following reasons;
(1), cable television cable and telecommunications, power supply cable parallel, field amplifier and devices hanging on at strand (Xuanhua cable TV network routing, partly through the telephone network, power supply network routing and Unicom), due to an unexpected string steel strand into alternating current, a power interruption of failure, it is difficult to find for a short time.
(2), cable TV, home appliance unqualified power interference caused by cable TV, find the line to be disconnected, gradually narrow range, and a building of several units, nearly a hundred households, this finding shall be for a long time, leakage, find easier to find, if minor leakage, maintenance personnel contact line device fault disappears, while the interval time appeared in a relatively short period makes it difficult to identify.
(3), cable system cable and power line laying at close range, if the Community supply line underground pipelines, line underground piping and cable TV line underground piping and pipe laying, building power cable protection and cable TV cable protection pipes not fully use the metal, and plastic protector tube magnetic field strength decreases, resulting in line AC interference shielding.
(4), in three-phase four-wire, 3-phase power supply circuit in the power imbalance produces neutral, with intermittent communication interference occurs.
(5), the Earth, in brackets and bad cable forming low resistance channel, AC interference.
(6), most communication interference appears in a new building or soil building site in the vicinity, and the new big TV be affected more than than old-fashioned TV.
Inhibition of AC power interference method
(1) plug AC cuanru system, strengthening the lines of shielding and grounding.
(2) to avoid transmission cable and the power of close parallel.
(3) the improvement of AC power supply, additional Exchange regulator power supply.
(4) use the excellent equipment.
(5) inspection of existing electrical power ripple coefficient is too large, Rectifier filtering elements for damage or deficiency, power supply performance is not good amplifier to be replaced, improve equipment supply index.
(6) large long-distance transmission line further separated out of range.
Repair an instance of the cases, the front-end computer room has a power interference
Recently, the front-end computer room individual channels every morning at eight and nine sometimes power interference, ten o'clock to sometimes appear normal at times. In the event of a failure, check the device power, the measurement of three-phase electricity are A phase, B phase 214V 196V, C phase voltage difference about 216V, 10V, often changes in the law was not found., mild-to-phase voltage difference when 3 ~ 5 volts, through to the Cabinet using electrical tuning, commutation, merge, power failure, the power supply voltage is lower than found 204 Volt, with many years of Czech Lord modulator has a power interference, use the shorter Japan power modulator without this phenomenon, when the power is less than 190 v, most of the modulator is a power interruption. Internal power supply power supply transformer grounding wire without touching the ground wire, and Cabinet also has a power interference, the ground wire connectivity, scroll up and down power interference mitigation of, but not scheduled power interference phenomenon has finally found a distribution room old regulator performance variation, take off voltage regulator, and observation of the invisible power interference phenomena. Example 2, a community has a power interference
A community has a power interference, through the maintenance of the test and found fault once-powered amplifier, check the front-stage input did not find power interference, disconnect the amplifier output, the discovery of green rust on insulator because the field connector didn't do waterproofing treatment, 60V supply voltage in the formation of shunt circuit, causing the power interruption, clean green rust lineRoad, troubleshooting. Case study 3, on whose behalf an optical receiver some users watching bad
A residential building users reflect TV look bad, there is a horizontal bar, the scroll up, scroll down to see failure in the daytime are lighter, while in the evening news is serious, and accompanied by images distorted beat phenomenon, continuous signal from back to front TV observation, white strips gradually become light that is there is a problem with the optical receiver out, test voltage (digital multimeter) 247-volt power supply, optical receiver 69 Volt alternating voltage, substitution effect-free optics. use uninterruptible power supply separate to the optical receiver is disconnected from the power supply, optical receiver all output signal, and gradually add universal TV ratings, found after the level of a residential building of the failure before it on the floor, the unit adopts breaking load method gradually excluded, to central unit 403 families fault elimination, user home, SsangYong separated for access lines, although not completely ruled out, but most users can watch TV in normal, unlike previous distorted beats, white road can only at night. Case study 4, low band program properly, the high frequency band program.
A community affected by the high frequency band appear TV hum modulation interference serious (TV L H section section normal, light, U of serious) interference phenomenon, I network frequency bandwidth 550MHZ, transmission 51 set analog signal from the TV screen, 13CH interference not apparent, slight interference 14CH, 15CH interference ratio 14CH interference significantly, interfering 16CH interference and 15CH, compared to the basic look of normal, 17CH 18, 19, 22, three channels interference see more obvious, 20CH images are distorted, beating 23CH image cannot see, test the amplifier's level and previous normal, replace the amplifier cannot resolve the problem, measuring power amplifier voltage within. power-amplifier found only 37V, reduce the power supply for additional long distance power supply, power supply, and troubleshooting. Case study 5, CATV horizontal bar users
Some plot 8 # entire building CATV horizontal stripes user 7 p.m. After serious interference, usually lighter, some scroll with the scroll down, and a few other buildings is not this behavior, use the Replace method to replace amplifier shipwrecks reactive, in maintenance through careful observation, discovered a serious fault, unit 3, unit 1, unit 2, 4 unit failure. Focus on measuring 3 unit, when you disconnect the line measurement of process failure disappears. The second day of the fault occurred, this time we first 3 unit user disconnection from back to front, second floor, breaking to fault disappears, recovery circuit to watch more than half an hour are normal, we go after less than a day failures occur again, this time we directly to 3 unit 2F, put your own body and line insulation, standing on wooden stool with gloves, when room 202, user fault line is disconnected. Grafted in fault occurs. When the hands straight contact 202 users online, then pick up no symptoms in this family line separator received double Dragon, the user no longer calls, troubleshooting. Case study 6, users do not see good TV.
Maintenance personnel on-site service, discovery TV screen has two horizontal stripes, striped is moved up and down, serious image distortion, farm are not synchronized, unable to watch, this phenomenon on low-frequency impact heavier, high-impact relatively light, dark field to see clear, bright field of view not obvious, a courtyard, 4 building, wuliubai users, this phenomenon is reflected. Measuring amplifier power 215 ~ 222V, socket contact is good, the power cable is not damaged, replace with the Replace method has no effect, and this phenomenon is not, turn the front-stage consider cable cable and strong electric parallel, contiguous or around without interference, a strong magnetic field, in addition to the new view along the building's construction, and other anomalies found in the end, take the low-frequency filter grounding method does not resolve, and then focus on the user to organize large amounts of resources working overtime to break load method excludes, fault to compression unit households, interference, but a few days, so that the fault has appeared many times users view and from very large to the maintenance personnel resulted in great pressure, and found a lot of user lines have different degrees of charged, building guard line pipe and cable TV devices with a slight brand impact phenomenon, while symptoms worse, for which the building wired devices and building metal isolation, fault disappears soon, to reproduce the failure. Last used self-made SsangYong separated for access, although not completely ruled out, but most users can watch TV in normal, unlike previous distorted beats, white road can only at night, users have no complaints.