Loss of signal is an unfortunate reality when building a cable system, however, there are effective methods for trouble shooting a cable plant. The key to troubleshooting lies in understanding where problems may occur, and why they may occur.

Signal loss: Most often, signal loss occurs between the main line distribution service tap, and the electronic device being used by the subscriber. Signal loss or degradation may also occur however, in any other portion of the system, i.e. service tap, splitter, DC coupler, power inserter, bridger amp, trunk amp, or even launch amplifiers. While mainline equipment failures are generally easier to locate, they can take longer to fix. Both powered (amplifiers, power supplies) and passive or non-powered (distribution taps, splitters). Mainline equipment can experience failure. With passive equipment, the nature of the failure is generally related to a barrier breach (i.e. water leakage) that has caused come sort of corrosion inside of the equipment.

Temperature fluctuations will loosen contact screws (centre pin screws) and will even pull mainline copper core out of connectors (because the copper centre and aluminum shield expand and contract at different rates). Keeping connectors tight and shrink-tubed is the most effective way of fighting this war! Also, many mainline cables today are using copper coated aluminum cores, which is very helpful.

Lightning or power surges can also effect passive line equipment. However, this is more rare, as the powered portion of the cable plant usually bears the brunt of any electrical surge problems. Powered amplifiers and any transformers will all have fuses and grounding protection, but fuses can blow, and grounding protection can fail. Multiple electrical spikes and lightning strikes can cause several amplifiers to blow simultaneously, making it much more difficult to locate problems. When this occurs, it is also a much more difficult task to get the cable plant up and running again.

Launch amplifier failure: It is generally a simple task to locate a problem with the launch amplifier, as the telephone will not stop ringing. The entire cable subscriber base will be without service, and they will most likely not be very happy about this. They will call to let the service provider know. If there is a problem with the launch amplifier, the subscribers will let you know. Ignore the telephone. After a few experiences of this type, the technicial will learn to recognize the problem, and will immediately go to the head end to rectify this problem.

TIP: It is an excellent idea to ALWAYS HAVE A SPARE LAUNCH AMPLIFIER ON HAND!!!

Without a spare launch amplifier in the event of a catastrophe, there is no way to service the subscribers. However, if the launch amplifier goes down and a spare is not available to replace it, check: fuses, equalizers, and pads. If all of these are in good working order, the amplifier WILL need to be replaced.

TIP: When troubleshooting the cable plant, it is a good idea to always have a voltage meter and an RF meter along - these will help to quickly check equipment and locate the source of the problem!

Partial failures: As with a complete failure of launch amplifiers, the entire cable plant will usually be affected, which means that this problem will be easier to locate. (Turn off the telephone as the constant ringing can make it difficult to concentrate on fixing the problem.)

Trunk Amplifier Failures: While these failures also effect large portions of the cable plant, they are also easy to locate, and the subscribers will inform the cable provider when there is a problem.

General trouble shooting: "Chasing Signal" is a good way to describe trouble shooting in cable systems. The technicial usually proceeds to the area where there is trouble, attaches an RF meter to a piece of inline equipment such as an amplifier or service tap, and checks to see if the RF signal is present.

• If there is no signal, the voltage should then be checked
• If there is voltage with no signal than an amplifier or a portion of the amplifier has failed.
• If there is no voltage, then there is a problem with the power, and the first, most obvious item to check is for blown fuses.

TIP: The purpose of general trouble shooting is to ISOLATE THE PROBLEM. In general terms this means going from device to device until the source of the problem is found!

In the case of no signal, it makes more sense to "troubleshoot backwards," away from the subscribers, towards the source of the signal.

Since voltage can travel both ways to power a cable plant, it is a good idea to have a GOOD WORKING KNOWLEDGE OF THE POWER SCHEME of the system. If this is not the case, then more troubleshooting will be necessary to determine why there is not power.

If the technician is willing to do the required legwork, they will gain experience, and most mainline problems will eventually become easy to find. Once found, they generally just take a bit of time to fix!

Service tap to end user device troubleshooting: Troubleshooting this portion of the plant is very similar to troubleshooting other parts, except that there are more variables within this area. All external connections may be subject to corrosion from weather, particularly if they are not properly sealed! These are also subject to damage by the subscriber, as are overhead cable lines.

If all user-end devices are non-functional, then testing the service tap that is supposed to service the area being effected, is the first step.

Service taps can fail for no apparent reason. If the failure of the cable service is being caused by the failure of a service tap, this can be established quickly, and a new tap, or portion of the tap can quickly be installed to bring back the service in the effected area.

Partial outages at subscriber locations can be more difficult to find and rectify. Again, isolation of the problem is the key technique to troubleshooting in these instances. The technician must establish where there is signal, and where there is not signal. Once this is established, troubleshooting is simply a matter of following cable lines, checking connectors and inhome splitters, until the source of the problem is found. In some cases, the technician should be sitting in the comfort of their own home, as it is the subscribers equipment that is broken or has failed. At times, the problem may also be that the subscribers equipment is not plugged in, or the coaxial cable is not, in fact, plugged into the equipment. Triple-billing for these instances is not unreasonable.

Digital signals, above all other kinds of signals, will be effected the most, by the least amount of difficulty within the system. This is because digital data requires a higher quality signal and a larger volume of the data to be put through accurately in order for the system to work correctly. Troubleshooting Internet data signals can be frustrating, as CCTV metres and monitoring equipment are generally designed to read the RF carrier inside the coaxial cable, rather than the digital signal or channel riding on that carrier. All of the readings may be correct, however the digital Internet service may still not work. It may be easy to fault the modem, however old equipment or cables may easily be at fault, for not allowing a sufficient quality or quantity of data throughput.

TIP: In short, to troubleshoot the cable system: Always check for loose connections, replace any suspect lines or equipment, and when in doubt, re-do, or replace!!

TIP: The best, and most invaluable tools for cable plant troubleshooting are: common sense and good problem-solving abilities knowledge of the cable plant an RF metre a Voltage metre, and, experience. All of these tools will help to make plant troubleshooting easier and quicker every time.