General-Electric-Co-P955A 电路原理图.pdf

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1、VOLUME R-24, MOST-OFTEN-NEEDED 1964 RADIO SERVICING INFORMATION /F / s? ; / S.“ T GENERAL ELECTRIC MODEL P955A MODULES iT I This radio uses three high-reliability modules in its construction. The modules are self-contaqed circuit stages, each grouped on a miniature circuit board, which themselves ar

2、e mounted on and soldered into the main circuit board just like any other component (transistor, capacitor, etc.). This method of manufacture provides high reliability at an optimum cost. In fact, it allows the cost of the module to fall into the same range as tubes or transistors. This means that d

3、efects in the circuits involved in the modules need only be replaced with a good unit. Almost always this will result in an easier, quicker, and more economical repair than would be possible if the serviceman were to try to locate and replace a defective component within a module. This radio uses su

4、ch modules in the converter, I. F. and Audio stages. CHASSIS REMOVAL 1. Remove volume and tuning knobs. 2. Remove two Phillips-head screws from cabinet back. 3. Remove seven hex-head screws from circuit board. 4. Label and unsolder wires going to speaker and battery terminals. 5. Carefully lift circ

5、uit board from cabinet. TROUBLESHOOTING IMPORTANT: The audio output terminals of the radio must be D. C. isolated from ground during servicing pro cedures. This is to prevent the audio output transistors from becoming damaged by excess voltages in the audio circuit. Therefore, care must be exercised

6、 in using test equipment that may cause a D. C. path to ground. The total battery current drain should always be as certained before proceeding with the servicing. These current readings should be taken with the receiver in the OFF” position. Total current is measured by placing a jumper across S1A

7、and measuring the current across the switch terminals of SIB. This current reading should fall between 20-27 MA. After noting this current, remove the jumper across S1A and place it across the terminals of SIB. Measure the current drain across the switch termi nals of S1A. This current reading should be approximately the same as the previous reading. Should any significant difference in current readings occur when making this check, a defective audio output stage is indicated. uj| 8 *8 9i g| sl IgFlgH - i ! | 1 I_!_ j g Q O X i 2 is Hi! llllsili 51 收音机爱 好者资料库 RadioFans.CN