FIRST AID

Radio Record, Volume I, Issue 2, 29 July 1927, Page 12

FIRST AID

DISABLED RADIO SETS Hirst aid treatment for "sick’’ radio sets that will enable the man who has only a slight knowledge of radio to recognise the trouble aud make the necessary repairs was prescribed by Lee Manley and W. EH. Garity at a meeting of the Americau Institute of Radio Iingineers. They pointed out that the sets as a rule do not go bad of themselves, The failure usually occurs while soine operation is taking place, such as plugging in the loud speaker, tutning the condensers, or making a change in the battery connections. If the set has been in operation for a month or six weeks, and has been giv- | ing satisfactory service for that period, the cause of failure is generally due to the. weakening of the batteries. | If the sect has been iu operation for a period of six mouths or a year the possibilities of trouble will increase. If the failure has becn gradual, the first thought would be that the tubes were worn out. Trifles Cause Trouble, _ If the breakdown is sudden, a mechanical failure might be expected in one of the movable connections, or pigtails, of a transformer may have burned out. If the trouble is due to a noise condition, the failure might be ascribed to dust or dirt accumulations on the condenser plates or other important parts of the receiver. The defect might also be due to a corroded soldered connection. It will require, as a rule, a rather long time for a soldered connection to corrode to such a degree as to cause this condition, The local atmosphere conditions under which the set has been operating may lave some bearing on the cause of failure. If the set has been operating near the seashore, and has been subjected to the action of_salt atmosphere, . sufficient corrosion may have .- taken nlace in the conncctions or other. metallic parts to introduce high resistance or leakage paths. Moisture may satur-. ate the cheaper grades of insulating material to such an extent as to cause high-frequency short circuits, Worn Mechanism, If a set has been operating for a long period of time and has given satisfactory results, and then develops noises and scratching sounds, one should not look for a loose connection in the wiring of the set, but rather for an open circuit in the moving parts. Worn tmechanical parts are often mis~ taken for loose connections in the wiring. The wiring is absolutely stationary, and it is not likely that it will be disturbed in the ordinary use of the set so as to cause a failure due. to. @ loose connection. ; Vernier drive-shafts and vernier plates will wear loose, and while apparently they are making perfect contact to the metal surfaces of the condenser, still when the set is bronght into a critical condition, as is the case when receiving distant stations, noises will occur that might be thoucht due to a loose connees tion in the wiring,