Galvin-Mfg-Co（Motorola）-ST-162 电路原理图.pdf

《Galvin-Mfg-Co（Motorola）-ST-162 电路原理图.pdf》由会员分享，可在线阅读，更多相关《Galvin-Mfg-Co（Motorola）-ST-162 电路原理图.pdf（2页珍藏版）》请在收音机爱好者资料库上搜索。

1、VOLUME R- 16, MOST-OFTEN-NEEDED 1956 RADIO SERVICING INFORMATION MOTOROLA INC. search tuner 77E535500 (model st-162) (Used in Auto Radio 69MF and others) GENERAL INFORMA TON This search tuner is a combination mechanical push button tuner (with manual tuning) coupled to a search drive unit. This syst

2、em provides three different methods of tun ing the radio: manual tuning; pushbutton tuning; search tun ing. The frequency range covered is 540 to 1600 Kc. The pushbuttons tune to any one of five favorite radio stations to which they have been pre-set. For search tuning, there are two different butto

3、ns; a TM (town) button for tuning the radio to strong local sta tions and a C (country) button for tuning the radio when farther away from local broadcasting areas. This radio will search radio stations with the tuner sweeping from either the high eno to the low end of the band or while sweeping fro

4、m the low end to the high end of the band. MANUAL, TUNING When the manual tuning shaft is turned, the tuning gear and pinion fear (see Figure 2) rotate the crown gear and pinion assembly (6), which rotates the split gear and bush ing assembly (7). As the split gear and bushing assembly (7) is fricti

5、onally coupled to the clutch and disc assembly (4). which is fixed to the treadle bar assembly, the treadle bar assembly moves the cores (5) in or out of the coils (LI, L4 h L5). Figure 3 shows that the different angles to which the treadle bar assembly may be moved, correspond to dif ferent frequen

6、cy radio stations. The power transfer se quence is as follows from the pinion gear of the manual tuning shaft (21) to the crown gear and pinion assembly (6), from the crown gear and pinion assembly (6) to the split gear and bushing assembly (7), from the split gear and bushing assembly (7) to the cl

7、utch and disc assembly (4), from the clutch and disc assembly (4) to the treadle bar as- FIGURE 1. MODEL ST-162 SEARCH TUNER contacts the planetary gear system, the planetary gear sys tem rotates when the manual tuning shaft (21) is turned. Because the search selector button has not been depressed,

8、the control clutch does not engage the carrier gear. Under this condition the planetary gear system is allowed to rotate without turning the motor (E2 -see Figure 9). PUSHBUTTON TUNING This tuner is equipped with five pushbuttons which may be set up in any sequence to tune any radio station within t

9、he tuning range of the radio. To set the pushbuttons, the station is first tuned in with the manual tuning knob;this adjusts the angle of the treadle bar assembly (see Figure 3) to an angle corresponding to a radio station. The pushbutton is then unlocked by pulling it out; this actually unlocks the

10、 adjustable cam on the push arm. When the pushbutton is depressed, the cam is locked to the angle of the treadle bar assembly and remains at that angle until changed. There fore, whenever a pushbutton is depressed it will return the treadle bar assembly to the angle to which the cam was set. FIGURE

11、2. MANUAL TUNING 98 收音机爱 好者资料库 RadioFans.CN VOLUME R-16, MOST-OFTEN-NEEDED 1956 RADIO SERVICING INFORMATION TUNING COILS (LI, L4. L5) TUNING CORES (5) , CORE BAR f-1-1 1 CARRIAGE CORE BAR g LINK (13 CORE BAR / SPRING (25) ADJUSTABLE CAM j/0v PUSH ARM X MOTOROLA Search Tuner Model ST-162 (Continued)

12、Treadle Bar Assembly approximate ly 30 to left of 0 reference-radio tuned to approximately 540 Kc Treadle Bar Assembly at 0 refer ence-radio tuned to approximately 1000 Kc Treadle Bar Assembly approximate ly 30 to right of 0 reference-radio tuned to approximatelv 1600 Kc FIGURE 3. TREADLE BAR ASSEMB

13、LY MANUAL TUNING SHAFT (21)- PINION GEAR PUSHBUTTON PUSH ARMS TUNING GEAR_ PINION GEAR- CROWN GEAR AND PINION (61- SPLIT GEAR AND- BUSHING ASSEMBLY (71 / CLUTCH AND DISC HI ASSEMBLY (4) W I COUPLING SPRING (26)v- DRIVE SHAFT (20) POWER TRANSFER GEAR SOLENOID - PINION GEAR- CONTROL CLUTCH CARRIER GEA

14、R- PLANETARY- GEAR- TUNER DRIVE SHAFT (22) ADJUSTABLE CAMS JREADLE BAR ASSEMBLY -CORE CARRIAGE TUNING CORES (5) | POWER TAKE DRIVE GEAR (8) OFF GEAR REVERSING SWITCH (E5) CLUTCH RELEASE ARM FIGURE 4. PUSHBUTTON TUNING SEARCH TUNING Search tuning provides a way of automatically tuning to the next rad

15、io station by merely depressing a search selec tor button. The search tuning mechanism can be operated by two search selector buttons marked TM and C; the T (town) button for search tuning strong local stations and the “C (country) for tuning weaker stations. When a search selector button is depress

16、ed, the follow ing occurs: 1. The sensitivity switch E6 is either opened or closed by the action of the sensitivity switching link (see Figure 5 and SENSITIVITY SWITCHING) and one of the search selector switches (E7 or E8) is momentarily closed. 2. With E7 or E8 momentarily closed the audio is muted

17、 and R34 is grounded (see Figure 7), which completes the relay (E4) circuit to ground. With the circuit complete, relay E4 becomes energized, grounding relay contacts A, Bl, C and D, and ungrounding contact B2. 3. Contact A is connected to the output stage and grounding this contact mutes the output

18、 during search. 4. Contact Bl switches R28 across bias resistors R29, R30, and R33. This reduces the bias on the trigge tube. With the bias lowered, the relay section of the trigger tube conducts sufficient current to hold relay E4 energized after switch E7 or E8 is opened. 5. Contact B2 grounds the

19、 cathode resistor R13 of the RF and IF stages. While sea ching, when contact B2 is un grounded, the bias of the RF and IF stages is determined by the position of switch E6 (see Figures 5 ti 7). Wltli switch E6 opened the bias is lowered whilesearching because the cathode circuit is completed to grou

20、nd through the additional cathode resistor R15. With switch E6 closed the bias re mains normal even while searching 6. Contact C completes the motor (E2) circuit to ground, which starts the search mechanism operating. It will be noted that the motor is connected to a reversing switch which is operated by an actuator linked to the treadle bar 99 收音机爱 好者资料库 RadioFans.CN