Emerson-Radio-and-Phonograph-Corp-853B 电路原理图.pdf

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1、VOLUME R-17, MOST-OFTEN-NEEDED 1957 RADIO SERVICING INFORMATION EMERSON RADIO e c 7 3s i _ o io o o : “tJ - O O - a- Eu u _ _ o . 0 oJlZZQi 11 O z o z cc h co a tr o u j a 30 收音机爱 好者资料库 RadioFans.CN STEP DUMMY ANTENNA SIGNAL GENERATOR COUPLING SIGNAL GENERATOR FREQUENCY RADIO DIAL SETTING OUTPUT MET

2、ER ADJUST REMARKS 1 .005 mfd. High side to grid (pin 7) of VI (12BE6). Low side to B - neu tral. (See Alignment Note) 455 KC Variable condenser fully open. Across voice coil. T2, T1 Adjust for maximum output. 2 Form loop of several turns one radiate signal into receiver. 1M0 KC M Across voice coil.

3、Trimm.r C-1B (D.c) Adjust for maximum output. 3 1400 KC T une for maximum output. Across voice coil. Trimmer C-1A (Ant.) Adjust for maximum output. 1. Generol Information SERVICING MODULIZED RADIO CHASSIS The same care should be exercised in repairing a moduli zed etched wiring radio chassis as is u

4、sed in regular etched circuit board repair (low wattage iron, stiff brush, etc.). Past experience has indicated that the majority of radio failures are due to tubes and components which are not included within a module (electrolytic, oscillator coil, volume control, etc.), therefore, the type of ser

5、vice required on modulized chassis will generally be the same as for conventional chassis. Since most of the R & C components in the R.F. and l.F. sections are in one module and the audio R & C components in the other, it would only be necessary to isolate the trouble to one of the modules rather th

6、an to a specific component. This should reduce troubleshooting time on the more difficult repair jobs, especially those which are of an intermittent nature. If a particular trouble could be isolated to a defective component as easily as to a defective module, or if a replacement module were not imme

7、diately available, it would be desirable to repair rather than replace the module. Information on the replacement and repair of a module is given below. 2, Replocement of o Module a-Remove defective module by dipping underside (dip soldered side) in a small solder pot (which is now commercially avai

8、lable) or apply a solder iron or gun with a square shaped tip to all of the risers at the same time. b-While the heat is being applied to all of the risers at the same time by one of the above methods, pull the defective module away from the etched circuit board. (Note the location of the module pos

9、itioning notch with respect to the etched board). c-Piace a new module in the etched board making certain to position it as the original and individually solder each riser in place or dip in a solder pot. Note: To reduce the possibility of interchanging modules during repair or orientating the modul

10、e incorrectly, several unused riser wires are clipped below deck MAM as can be noted on the module schematic. The combination of clipped riser wires are different between the two modules. Since there are no holes in the etched circuit board to correspond to these clipped risers an exact replacement

11、module can only be inserted the correct way. 3. Repair of Modules The module diagrams shown on the schematic provide enough information to determine whether or not it would be practical to re* pair the module for a particular defect and if so how to proceed. These diagrams not only show the risers t

12、o which a component is connected, but also to which deck (A, B, C) it is physically mounted. This type of information is necessary to properly isolate a defective module component by cutting a riser wire and to show what other components are removed from the circuit at the same time. If it is practi

13、cal to repair the module, then all modular components removed from the circuit (connected above the point where the riser is cut) must be replaced by conventional components soldered directly to the dip soldered side of the etched circuit board. a-Determine defective component by general troubleshoo

14、ting procedures. . lRefer to proper module diagram on schematic and decide whether or not this component could be isolated (by cutting riser wire or wires) without disconnecting too many other components from the circuit. c-If repair is practical, cut required riser wire or wires and connect replace

15、ment component or components to dip-soldered side of etched board (across proper riser wires) rather than to module itself. Note: A diagonal cutters should never be used to cut a riser wire between decks since permanent damage could result. The pinching action of a diagonal cutter could crack one or more of the module decks. A very fine toothed saw blade or a small hand powered tool with a 1/32* abrasive disk should be used for this purpose. 31 收音机爱 好者资料库 RadioFans.CN