Galvin-Mfg-Co（Motorola）-ST-60-Tuner 电路原理图.pdf

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1、MANUAL OF 1951 MOST-OFTEN-NEEDED RADIO DIAGRAMS SERVICE M A N U A SOLENOID TUNER MODELS - ST-60 ST-78 CONTROL HEAD PUSHBUTTON CABLE RECEPTACLE ST-60 ST-78 ER SET-UP MANUAL TUNING- STATION SET-UP KNOB SHAFT GENERAL Solenoid Tuners ST-60 and ST-78 are used in Motorola electric push-button standard aut

2、o receivers. Fundamentally ST-60 and ST-78 tuners are the same. The two tuners differ in push-button switch lead lengths, oscillator coil, sleeve and shield, tuning cores, antenna trimmer and cover over ST-60 carriage. These tuners are similiar to the original Motorola ST-54 solenoid tuner. This is

3、a 3 gang permeability type tuner operated by a solenoid. Five pre-set and one manual tuning positions are provided. The frequency range is 535 to 1600 kc. The pre set positions can be set to any frequency within this range. The tuner is designed to operate satisfactorily with 4. 5 to 7. 3 volts inpu

4、t. Before attempting any service work on a tuner that operates too slowly or one that doesnt operate at all, check the battery voltage directly at the receiver spark plate. Normally, this voltage is 6. 3 volts. At the moment anypush-hutton is pressed, the voltage atthe spark plate should not drop to

5、 less than 4. 5 volts. If the voltage is less than 4. 5, it is an indication of poor wiring between the car hattery and receiver or a defective car battery. This tuner depends on dash-pot action between the plunger and the solenoid for proper operation. When the fit between the plunger and solenoid

6、is too tight, the air cant get out fast enough. The result is a slow or sluggish op erating tuner. All ST-60 and ST-78 tuners have an adjust able air release in the solenoid end plate. SeeFigures 1 if it trips too late, the plunger may hammer violently or should the solenoid switch fail to trip, the

7、 plunger would be held within the solenoid. END VIEW OF TUNER ECCENTRIC WASHER SCREW AIR RELEASE HOLE I SOLENOID END PLATE FIGURE 3. AIR RELEASE ADJUSTMENT ACTUATOR ROD TURNS 1/6 TURN 160*) MOVEABLE RATCHET RESET FOR NEXT CYCLE FIGURE 4. PLUNGER RATCHET MECHANISM PUSH FIXED RATCHET 1/32BACK INTO PLU

8、NGER BEFORE TIGHTENING SET SCREW. IMPORTANT WHEN ADJUSTING MAKE CERTAiN 1/64TO 1/32CLEARANCE iS IN ALL 6 POSITIONS FIGURE 5. PLUNGER RATCHET ADJUSTMENT SERVICE NOTES FAILURE OF SOME LEAD SCREW TO ENGAGE IN SET-UP GEARS If some of the lead screws fail to engage in the set-up gears during station sett

9、ing up procedure, check the gear lever to see if it is bent. When the set-up button is pushed in and the gear lever latches on the detent lever, the set-up gear train should be parallel with the tuner end plate and the bottom of the gear train should be resting on the raised portions of the tuner en

10、d plate. LUBRICATION Should lubrication ever be required, it is recommended that a very fine grease, commercially called DOW-CORNING Silicone (DC 44 Medium Grade), or its equivalent be used. Remove all old and sticky lubricant with a solvent such as carbon tetrachloride and then, very sparingly, lub

11、ricate only the following points: 1. Carriage guide rods. 2. Actuator rod, 3. Manual lead screw. Do not lubricate or permit lubricant to get on Selector Switch contacts. MANUAL OF 1951 MOST-OFTEN-NEEDED RADIO DIAGRAMS Tuner ST-60, ST-78, continued. FIGURE 6. SOLENOID SWITCH ADJUSTMENT LEAD DRESSING

12、Make* sure that the selector switch and solenoid coil leads are dressed so that carriage plate does not rub a- gainst them. Leads rubbing against the carriage plate may cause the tuner to stick, especially at the high frequency end. REPLACEMENT OF SOLENOID COIL OR SOLENOID PLUNGER Should replacement

13、 of the solenoid coil or solenoid plunger be required, it will be necessary to replace the en tire tuner. A close fit between solenoid plunger and sole noid coil form is required; a proper match can only be secured at the factory. When service of this kind is re quired, return the tuner to the facto

14、ry for exchange. ALIGNMENT In the event that some part of the R.F. circuit has heen changed or the adjustments shifted by mishandling, it is suggested that the receiver be realigned. Follow the align ment instructions found in the receiver service manual. The tuner must be in good working order and

15、assembled onto the chassis hefore attempting alignment of its tuned circuits. TO REPLACE ANT. R.F., OR OSC. COILS 1. Unsolder the two lugs holding the coil to the tuner plate. 2. Carefully remove the old coil. Save the thin paper wash er that is found at the base of the coil. 3. Slip the paper washe

16、r over the replacement coil and slip coil into shield can. 4. Orient coil so its lugs are in same position as before and resolder to tuner plate. 5. Reassemble tuner and install in receiver. 6. Realign ANT., R.F. and OSC. stages per instructions found in the receiver service manual. ADJUSTMENT OF GE

17、AR LEVER LATCH The gear lever latch holds the station set-up gear train in position while setting up stations. Failure of the latch to engage properly when the set-up hutton is pushed in will result in the inability to set up pre-set stations. Failure of the latch to disengage after station is set-u

18、p will result in faulty automatic tuning because the lead screws might not seat themselves properly against the tuner end plate. Fig ure 7 shows the latch detail and adjustment. TO REPLACE ANT. R.F. OR OSC. COIL TUNING CORES 1. Remove the carriage return spring. 2. Move the carriage plate back as fa

19、r as it can go. The tuning cores can now be screwed out or in hy grasp ing the portion that sticks out the back of the coil. When installing a new core, make sure that the insulating washer and adjustment clip are replaced properly. The insulating washer goes on the core side; the core adjustment cl

20、ip has an ear on it and this ear must fit into a hole in the bakelite insulator on the carriage plate. Refer to Figure 8. 3. Replace the carriage return spring. 4. Install tuner in receiver. 5. Realign ANT., R.F. and OSC. stages following the in structions found in the receiver service manual. PLUNG

21、ER RATCHET REMOVAL To remove ratchets, proceed as follows: (Refer to Figure 8 for parts identification). 1. Remove gear plate mounting screw (55). 2. Pull out actuator rod (46), Dont lose washers (83), (88) and (89). 3. Remove stop plate bracket (4) by sliding it out of the retaining slots. 4. Loose

22、n setscrew (50), 5. The large fixed ratchet (34), small floating ratchet (35) and ratchet spring (70) can now be removed. 6. Reassemble in reverse order. TUNER HANGS UP The beginning of this trouble is usually a condition where the tuner runs wild (fails to stop at a station). E- ventually, the stop

23、 plate gets hung up by getting on the wrong side of the station stops (56). The cause of the trou ble is that the selector switch (74) does not turn the correct amount with each dash of the plunger. Since the actuator rod (46) determines the rotation of the selector switch, it is usually at fault. C

24、heck the twist in the actuator rod. It should be 82 degrees. Also check the fit between the head end of the actuator rod (46) and the rotary section of the selector switch (77). We have found that some sloppiness sometimes occurs at this point. If the fit is loose, replace the actuator rod (46). This can he easily done by removing gear plate mounting screw (55).