Radio Technique George M Myers SOMETIMES YOUR RADIO starts acting peculiarly servos slow down get twitchy range goes nothing controls start affecting another through long series bewilderments What about Remember back stated isnt technicians column Thats still true dont have technician use head First try isolating system outside interferences Take radio system Out plane string out wooden table Now turn everything work sticks see problem has gone away has have clue about what next arrangement servo wires within airplane can have significant effect sys tem regardless much paid times necessary good per formance careful rearrangement equipment keep servo leads wire pushrods landing gear other bits metal away receiver antenna Try price right making installation first time its good practice put battery forward servos middle receiver rear antenna far system wiring possible Lets pretend stringing out airborne set didnt help Consider does problem ap pear certain control moved case servo may have dirty po tentiometer damaged gears noisy motor Exchanging servos will help de cide servo culprit may decide open up investigation Assuming have no service manual would good idea sketch parts remove identify bits tape grease pen cil marks can get back together correctly Slip motor out place may glued remove gear let run free Now turn set displace control servo motor should run continuously direction its fault trouble will return Assuming motor isnt fault move shaft drives servo output wheel also connected servo potentiometer cases potentiometer dirty youll know Most often thats needed wipe clean piece tissue lubricate track reassemble servo Still havent found trouble Push gently components amplifier board using dowel balsa stick may find loose component wire Solder back place 60/40 rosin-core solder 1/8 diameter pencil-point tipped soldering iron rated 27 watts less Lets say servos OK Try measur ing battery voltage servo plugs should read about 48 52 volts shouldnt drop 1 / 10th volt servos moving bigger change grounds suspecting broken wire defec tive battery pack Measure voltage plug pack voltage drop less servos moving previ ously go looking broken wire likely places next plugs place wire exits case Tug lightly wire turn comes apart Nate RC Manager Kemp Bunting right hand youve got culprit Examine switch harness carefully because takes lot abuse Work switch few times see its dirty spray TV tuner cleaner may help same treatment good dirty plugs can pretty noisy Still no answer Try recharging system before anything else charger may doing its job After full charge battery pack should read about 58 volts reading 54 volts less good grounds suspecting charger Now before rushing off junk charger give little consideration wall socket its plugged charger probably designed work 115 volts AC Put less get less out lights house light plugged socket seems dimmer neighbors may have problem house wiring thats left receiver youre technician let manufacturer fix may have cracked crystal loose elements IF cans cracked circuit board other troubles youre equipped fix things youll just make worse havent said anything about trans mitter best way differentiate between transmitter receiver problems test someone elses transmitter Another manufac turers transmitter frequency will work system just fine few rare exceptions might have noisy potentiometer control sticks Unless have General Class FCC Radio Operators License leave alone Let manufacturers Service Center take care some cases particularly persistent overcharging battery pack has taken place electrolyte driven out cells leads increase internal resist ance cells can make some radios very nervous example fix worth mentioning new battery pack Sure may able solder replacement cell two damaging pack should consider packs days potted resist vibration makes job trouble its worth battery pack usually cheaper new plane right Thanks go Wally Zober Suffolk NY Falcons suggesting theme column address 70 Froehlich Farm Rd Hicks ville NY 11801 14 Model Aviation Its nice modelers helpful another know Steve Sauger appre ciative volunteer loaned him servo during 1975 Nats Stinson Station Wagon could go win second RC Scale gain place US 1976 World Championships Team Sauger also won Sterling Models Award plaque plus *100 check having model earned static pointsand qualified making official flight President Johnny Clemens middle shown presenting Sterling Award Sauger assisted