Emerson-Radio-and-Phonograph-Corp-120485 电路原理图.pdf

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1、zzmHz T3oora)ia) mn-juniTt VOLUME R-20, MOST-OFTEN-NEEDED 1960 RADIO SERVICING INFORMATION EMERSON RADIO Model 880, ATLAS, EXPLORER, VANGUARD, (For alignment points and transistor locations, see drawing on page 35) TRANSISTOR REPLACEMENT INFORMATION* TRANSISTOR PAIRS Q1 815051H 815051A Q4 815054A 81

2、5054B CONDITIONS FOR VOLTAGE READINGS Voltages indicated are positive D.C. All Measurements token between points and chassis. Voltage measurements taken with; (a) VTVM _ _ w , Fresh 6 Volt battery supply. Four V/i Volt con ventional penlight cells. f Note: Should Mercury or Nickel-Cadmium bat teries

3、 be used, an approx. 15% lower voltage reading will be obtained from the battery supply which is considered to be perfectly normal. Bear in mind that the voltage supply will vary slightly with the type and condition of batteries used. Volume control set for minimum volume. Variable capacitor fully c

4、losed and no signal ap- pl ied. 5. Nominal tolerances in component values make possi ble a variation of 15% in readings. Caution - When taking voltage checks, avoid accidental shorting across transistor leads as It may cause tran sistor damage. Do not use a non-vacuum tube-type volt meter as the rel

5、atively low shunt resistance of this type of voltmeter con easily disrupt the transistor bios and result in erroneous readings os well as damage to the transistor. (b) (c) (d) 0-5- 1ST AUDIO 815055 0-6 - DRIVER 815056 0-7 & Q-8 - OUTPUT 815057 ANY COLOR Yellow Dot Yellow Dot Green Dot Orange Dot Blu

6、e Dot Red Dot Violet Dot Brown Dot NOTE: * Because of the small physical size of the transistors, the 1st three digits, “815”. have been replaced by the letter, *EM for Emerson. The ,E* also signifies that these tran sistors have been made to our design tolerances. These sets utilize an etched circu

7、it board chassis 120374 and 120485 identified by part number 630225 and 630243 respectively. The part number can be found on the etched circuit side of board. A paper label located on the external connection jack, containing the last three digits of the chassis number, is another means of identifying the chassis. CAUTION: As with all transistorized equipment, do not place close to a hot radiator nor keep in an unventilated area such as the rear window shelf in an automobile. High heat might cause damage. 36 收音机爱 好者资料库 RadioFans.CN