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Electronic Troubleshooting
Too often RC sailors jump to the wrong conclusion about what is wrong when their electronics don't work well, or at all. Many have waited for the round trip to Hitec repair just to find out the part they sent was not the problem. Since the RC Laser has a simple uniform system, I have written this article to help you find the problem quickly and with some certainty. That said, electronics are fickle! What follows is a trip through the entire electronic system. When you reach a Bold Blue Italicized Symptom, what follows is the troubleshooting section for you to follow. Outline of Electronic System The transmitter is what you hold that sends your commands to the boat. It is often called the radio or controller. Potential problem areas are the potentiometers (one for each channel), the battery compartment (including the batteries), the antenna, and the crystal socket. The receiver is a small box mounted under the port deck on velcro. Printed on this unit are the words Battery Eliminator Circuit (this was used in RC cars years ago. It takes a 7.2V battery source and drops the voltage to 6V.) This is a solid-state unit. Potential problem areas are corrosion on the circuit board, the crystal socket, and the wire prongs inside the sockets for the three wiring plugs. Crystals are the units that plug into the face of the Transmitter and the end of the Receiver. These crystals are marked TA for the Transmitter crystal, and RA for the Receiver crystal. They are not interchangeable! Potential problems include corrosion on the pins, or that they have missed the actual sockets when being plugged in. The switch is mounted in the deck with a rubber switch gasket protecting it from water intrusion. Potential problem is corrosion on the metal contacts of the switch mechanism. The battery holder is the case that holds four batteries. Potential problem is the metal contacts. Rust and corrosion are problematic on this cheapest component of the electrical system. There are two servos in the boat. The forward one is the sail servo, or sail winch. This is an extremely reliable unit to the point that I never suspect it. The small steering servo is in the rear of the cockpit. This servo is more prone to problems if not kept dry and clean. How does it work Movement (physical energy) of the control sticks on the transmitter operates the respective potentiometer that converts this command into electric energy. This energy is then converted to a radio signal by passing through the transmitter band tuner and the frequency crystal. The strength and quality of that signal is a function of the battery strength, quality of the electrical contacts, the radio band tune accuracy, the crystal frequency tune, and the antenna. At the boat, the receiver receives the radio signal through the antenna, converts it to electrical energy, and routes the signal to the correct servo. The potentiometer in the servo interprets the signal and tells the servo motor what to do. The motor drives the gears and the physical action results. The battery power in the boat goes through the switch and then to the receiver. The receiver passes along this power to the respective servos So Let's Troubleshoot! Symptoms: Nothing works; short range; erratic behavior These symptoms are all a result of the signal not getting through. Duh! The first concern is electrical power on both ends. Batteries - Know without a doubt that you have fully charged and serviceable batteries installed. It is wise to install brand new alkaline batteries to check the system. If only one rechargeable battery cell is weak, it will prevent proper charging of all the other cells. Sorry, but it is easy to install batteries incorrectly, especially in the transmitter. Double check. You should have a green light on the transmitter when turned on. Make sure that the all batteries are making contact with each other and the metal prongs of the transmitter. Transmitter Antenna - Make sure the antenna is screwed in hand tight. Transmitter Crystal - On the lower right front of the transmitter is a small plate with frequency information. Pull out this crystal holder and re-plug the crystal a couple of times to clean the posts. Boat Switch - If nothing works on the boat, move the switch back and forth several times. You should see and hear a slight "jump" in the servos. . It is normal for the switch to be forward when "on". If the rubber gasket is ripped, water may have entered the switch. If so remove it, find the slits in the end of the case, insert a knife blade or small screw driver and pop open the case. Clean and inspect switch. Boat connections - The red connector from the battery holder to the switch should be examined. Unplug and plug several times to see if it will clean itself and make contact. Inspect the three black connectors that plug into the side of the receiver. Again, unplug and plug several times in an attempt to make contact. Look carefully at the small wire prongs inside the sockets in the receiver. These prongs are fragile and can be bent. Hold the receiver so you are reading the print on the side of the receiver, that puts the sockets to the right. The black wire on each plug must be to the right. Receiver Crystal - Crystals are fragile and do not take banging around, so handle them gently. Removing the crystal from the receiver may take a pair of tweezers or small needle nose pliers. Check the pins on the crystal for signs of corrosion. Unplug and plug several times to clean the contacts. Alert - The socket for the receiver has no guide to make sure the crystal pins hit the holes in the socket and it is hard to see inside. It may be worth removing the cover of the receiver (see Receiver below) to get a good look at the socket and make sure the crystal is plugged in correctly. It does not make any difference which pin goes in which hole. The crystal in the transmitter is mounted in a holder and rarely misses the socket. Receiver - There are two small slits on either end of the receiver. Stick something flat (small screwdriver, knife blade, etc) into these slits and catch will release. There is just a circuit board inside, so no parts will come flying out. Look for signs of corrosion, dry and clean. Lubrication - Some sailors, especially if they sail in salt water a lot, prefer to lubricate electric fittings. Caution: Some lubricants conduct electricity and are not advised. Look for a non-conductive lubricant. On the other hand, if you lubricate connectors with a non-conductive lubricant, the passage of electrical current will stop. Best not to lube connectors unless you know the lubricant conducts electricity. Still no Solution??
At this stage you have checked the potential signal and power problem areas. If you have not solved the problem, the best solution is to start trading components until you identify the culprit component. The best bet is to contact another RC Laser owner and start substituting his working components until you identify the problem component. Symptom: Erratic movement of servos (jitters, glitching, etc.) We have written a separate article to deal with is this situation. Please see "The Big Twitch". |