RCA-Victor-Co-Inc-RC-1164B 电路原理图.pdf

《RCA-Victor-Co-Inc-RC-1164B 电路原理图.pdf》由会员分享，可在线阅读，更多相关《RCA-Victor-Co-Inc-RC-1164B 电路原理图.pdf（3页珍藏版）》请在收音机爱好者资料库上搜索。

1、VOLUME R-18, MOST-OFTEN-NEEDED 1958 RADIO SERVICING INFORMATION rca Victor Battery-Operated Pocket Radio Model 9-BT-9 Series Model 9-BT-9 Series TcT The Transistor Six” Chassis No. RC-1164A, RC-1164B Model 8BT9, RC-1164, is practically identical. (See pages 147 and 148 for additional service hints a

2、nd alignment facts.) R2I R2 C3 Printed Circuit Board Wiring and Components View from Wiring Side Circuit Board No. 961919-1 Chassis No. RC-1164 A S V Ceo A The assembly represented above is viewed from the wiring side of the board The printed wiring, on the near side of the board, is presented in ph

3、antom” view superimposed on the component layout of the reverse side TI OSC COIL Ql _2NI40 CONVERT -Rl ! CRITICAL LEAD DRESS Dress leads and components at gang so as not to in terfere with rotor plates. Dress lead from antenna to gang ant terminal away from metal parts as far as practicable. Check f

4、or possible solder shorts to volume control knob from printed circuit wiring. Antenna terminal of gang must be bent to insure clear ance to output transformer. Dress ”B lead from ON-OFF switch to battery under positive ( + ) lead of Cl6. Dress antenna rod to clear end of case and such that antenna t

5、erminal does not interfere with closing of case back T6 OUTPUT- TRANS. j rM iil n CSrT 13 3 Z Ml RS - m-iV ci4 I v i R10 y siuJL Jw i S i r DETECTOR DIODE CR 2 OVERLOAD DIOOE Q5 2NI09 OUTPUT Q2 2N139 1ST. l-F Q3 2N139 END. l-F Q 6 2NI09 OUTPUT CRi DETECTOR DIODE Q4 2N109 A F AMP Q5 2N109 -1+c DRIVER

6、 BLU. YEL C.lv/ VOLTAGES MEASURED WITH VOLTOHMYST SHOULD HOLD WITHIN *20% WITH NEW BATTERY K lOOO- ALL RESISTANCE VALUES IN OHMS. ALL CAPACITANCE VALUES LESS THAN 1.0 IN MF AND 1.0 ABOVE IN MMF EXCEPT THOSE INDICATED z TERMINAL CONNECTIONS FOR T2t T3 T4 iti - : TRANSISTOR SOCKET CONNECTIONS 1 4 3 AL

7、TERNATE TRANSISTORS 2N140 Converter 2N4U 2N139 I-F Amp. 2N409 2N109 Audio Amp. 2N407 BATTERY CURRENT 146 收音机爱 好者资料库 RadioFans.CN VOLUME R-18, MOST-OFTEN-NEEDED 1958 RADIO SERVICING INFORMATION RCA Victor Model 9-BT-9 Series, Chassis RC-1164A,-B, Continued SERVICE HINTS Recommended Test Procedure Use

8、 signal tracing or signal injection as basic test procedure in conjunction with voltage measurements. Make stage-by-stage check by injecting signal from signal generator and checking with a high-gain oscillo scope (at least .03 volts/inch). Oscillator action must be stopped in order to measure RF si

9、gnal at converter base since oscillator signal also appears at this point. Oscilla tor action can be stopped by touching a finger to oscilla tor section of the tuning condenser. NOTE. All transformers are step-down type and will show voltage loss from primary to secondary. Extreme care should be use

10、d to avoid accidental short ing of transistor elements to circuit ground. This is es pecially true of the output transistors; if the junction of R18-R19-R20 should be accidentally grounded for a few seconds, the output transistors would be permanently damaged. It is possible to damage a transistor w

11、hen testing cir cuit continuity. Since a transistor needs only low voltage applied to its terminals for conduction, testing continuity of a circuit which includes a transistor can result in mis leading continuity indications. To avoid transistor damage and misleading continuity indications, remove t

12、he tran sistor from the chassis before making continuity tests of its circuit. 1. The first thing to check when the receiver is inopera tive, is the battery. With the receiver turned on, a new battery should show 9 volts although the receiver can be expected to operate on any battery which checks be

13、tween 6 volts and 9 volts. 2. To check for a ctrcuit defect which would cause exces sive battery drain, an overall current measurement and supplementary voltage measurements should be made. For reasons explained above, continuity measurements can be misleading. 3. Signal tracing by injection of a si

14、gnal from a signal generator is done on transistor radios in exactly the same manner as with conventional vacuum tube radios. The signal generator should be connected (as in past practice) in series with a capacitor to avoid shorting out bias voltages. With the transistors used in this receiver, the

15、 BASE is the signal input terminal (corresponding to signal grid of tubes), the COLLEC TOR is the signal output terminal (corresponding to plate of tubes), and the EMITTER is the common ter minal (corresponding to cathode of tubes). 4. The output of this receiver is of the Class B type. It should be

16、 noted that in Class B output the battery current increases noticeably with increased signal in put. Refer to the schematic diagram for current speci fications. 5. Application of a signal from a signal generator to the input (B) of Q1 will stop oscillator action (R-F signal can not be injected at th

17、is point although 455 kc I-F signal can be injected). 6. Measurement of oscillator signal strength with an oscilloscope at the input of Q1 (base contact) will give an indication of oscillator performance. Voltage should be 0.20 to 0.70 volts peak-to-peak. 7. D-C measurements should be made only with

18、 a sensitive voltmeter, such as an RCA VoltOhymst. 8. Interchanging transistors in the I-F stages may neces sitate realignment. 9. The transistors and the printed wiring board can be readily damaged by excessive heat. When soldering on the printed wiring board, use a soldering iron which is both HOT

19、 and CLEAN. The soldering operation can then be completed quickly with a minimum of heat radiation to components. ALIGNMENT PROCEDURE Test OscillatorFor all alignment operations, connect the low side of the test oscillator to the common positive* wiring and keep the oscillator output as low as possi

20、ble to avoid AVC action. Step Connect High Side of Sig. Gen. to Sig. Gen. Output Dial Pointer Setting Adjust for Max. Output i #2 terminal of ant. assembly LI 455 kc Quiet point near 1600 kc T4 3rd I-F T3 2nd I-F T2 1st I-F 2 Repeat Step 1 3 Short wire placed near antenna for radiated signal 1400 kc

21、 1400 kc rock gang trimmer* Cl-B (osc.) 4 600 kc 600 kc rock gang T1 osc. coil 5 Repeat Steps 3 and 4 * Oscillator trimmer is located on bottom of gang. Production Changes 1. R4 was 1000 ohms. R5 was 220 ohms. 2. C9 was .03 mf. Cl2 (.005 mf.) removedit was connected from collector of Q4 to gnd. C16

22、(45 mf.) was a wire-in type of capacitor in early production. It may be either a wire-in type or upright type in late production. Chassis Components View from Back Side CR2 OVERLOAD DIODE i Q3 ce C9 CRI DETECTOR DIODE Q6 2NI09 OUTPUT 455 2NI09 OUTPUT MATERIAL-STEEL OR BRASS THICKNESS OF 254 COIN. To

23、ol Required for Removal of Chassis Mounting Nut 147 2NI39 2ND. t-F 收音机爱 好者资料库 RadioFans.CN VOLUME R-18, MOST-OFTEN-NEEDED 1958 RADIO SERVICING INFORMATION RCA Victor Model 9-BT-9 Series, Chassis RC-1164A.-B, Continued SERVICE PROBLEMS AND REMEDIES Distorted Only On Weak Stations Or Only On Strong St

24、ations When distortion is present and varies with the strength of the station signals, it indicates an abnormal condition in the circuit of those transistors whose bias is AGC con trolled. Distortion only on weak stations is most often due to unsatisfactory operation of the detector. The diode shoul

25、d have a slight initial forward bias. Check for presence of this bias voltage, check to see that polarity does not re verse with signal and that AGC voltage with signal is of proper polarity (base to emitter voltage should decrease with increase of signal). Distortion on strong stations indicates th

26、at the transistors are being driven to cutoff by a strong AGC voltage. An overload diode is used to reduce the gain of an IF circuit only on strong signals. Check terminal voltages and the overload diode. Transistor radios will not handle large vari ations of signal as well as vacuum tube radios, an

27、d it may be that on excessively strong signals the best solution is to turn the radio so that the antenna will pick up less signal. Regeneration An IF transistor having exceptionally high gain may cause regeneration on weak signals. A possible correction for this difficulty is to interchange the two

28、 IF transistors realignment is advisable after any change of transistors in the IF circuit. If a type 2N140 transistor is used in place of a type 2N139 transistor, regeneration may occur. Check for use of correct type of transistor. Two specific types of regenerative squeal have been found in the Tr

29、ansistor Six. The first type in which the audible sound can be controlled by the volume control has had several causes which were as follows: 1. High internal battery resistance. A new battery cor rects the trouble. 2. High resistance riveted connections at battery leads on printed board. This troub

30、le can be overcome by soldering the rivets to the printed wiring. 3. High resistance connections at chassis mounting spacer. This condition is evidenced by a change in the fre quency and intensity of the squeal when the tuning condenser mounting screws are first loosened and then tightened. The spac

31、er and the mounting screws are in the tuning condenser “ground” circuit and elec trolytic action between the copper wiring and the die- cast zinc spacer results in corrosion and high resistance joints. A 3-point wire jumper should be soldered be tween the three copper areas at the tuning condenser m

32、ounting screws. The spacers now being used are copper plated and can be soldered to the wiring. 4. Stripped tuning condenser mounting screw. The third tuning condenser mounting screw is also used as part of the tuning condenser “ground” circuit. The screw must be long enough to hold securely in the

33、condenser and yet not long enough to touch the tuning condenser plates. 5. Rosin joint at tuning condenser mounting screw. The third tuning condenser mounting screw mentioned above is soldered to the printed wiring. Some cases of poor soldering have resulted in rosin joints. 6. The mounting lugs of

34、IF transformers T3 and T4 are used for ground interconnections. Loose rivets can re sult in intermittent regeneration. Solder a jumper wire between the two mounting lugs of each can. No Signal In cases of “no signal,” the first step is to check battery voltage with set turned on. New batteries are 9

35、 volts, but transistor radios will operate on batteries as low as 6 volts. If the battery is O.K., check terminal voltages. There can be short-circuits in trcinsistor radios just as in any other radio. One significant difference is that in a transis tor radio, there is insufficient power to burn a r

36、esistor. Transistors have no filaments to burn out, but lead wires can be broken. Battery leads and phone jade leads are the most likely source of such trouble. Transistors them selves should be the last items suspected. Weak RF/IF Signal Transistor life in normal service has no known limit; service

37、 deterioration is so negligible as to be dismissed without further thought. In all cases of RF/IF low sensitivity, first check terminal voltages. Although voltages may vary widely without greatly affecting stage gain, the voltages should all have the same proportion of variation. The bias voltages a

38、re the most difficult to measure but must not be neglected. A transistor having a normal “forward” bias of 0.15 volt will have a slight decrease in gain when operating with a bias of 0.12 volt but may have a great decrease in gain when operated with a bias of 0.10 volt. If a large voltage dis crepan

39、cy is found it will be necessary to remove transis tors before making resistance measurements in localizing the trouble. Where a transistor stage shows low gain, shunt each bypass capacitor in that stage with another capadtor to detect open capadtors. Alignment should be checked in all cases of low

40、RF/IF sensitivity. There is only one core to each IF transformer but in some cases two peaks may be reached, one peak being higher than the other. If a transformer can not be peaked, it may have to be replaced first check trans former terminal connedions. The following are alignment suggestions: 1.

41、IF transformer will not peak at 455KC may be either defect in transformer or defective transistor (IF or converter) try replacing transistor before changing transformer. An open bypass capadtor in the dreuit of that transformer could give an unsatisfactory peak ing condition. 2. IF transformers may

42、be peaked incorrectly maximum gain is obtained when cores are peaked at the “farth est in” peak. Other possibilities of low RF/IF sensitivity are as follows: 1. Incorrect transistorif type 2N139 is used in place* of spedfied type 2N140, conversion gain will be down and osdllator section may fail to

43、operate when battery voltage is down slightly. 2. Resistor value change in osdllator or converter stage measure osdllator a.c. voltage at Q1 base (should be 0.20 to 0.70 volts p-p)measure d.c. voltages remove transistors and check resistors in converter dr euit; if transistors are soldered in, unsol

44、der one end of suspected resistor and measure without removing transistors. 3. Detedor diode reversedoutput is down slightly. Check by noting polarity of AGC voltage at the diode source. AGC line voltage at the diode will become more positive (or less negative) in resped to dreuit ground with signal

45、 increase. Audio Distortion One type of audio distortion is regeneration due to low capacity filters and/or high resistance joints. Because the output transistors are in a “Class B,” dreuit, even a small change in bias may result in distortion. The no-signal emitter or colledor current of each of th

46、e output transistors should be 1.5 to 2 ma with a new battery. A bias voltage of 0.1 v. is required at that current drain. Negative feedback is used to reduce distortion, the feed back resistor R22 is 82K. If the resistor is conneded to the wrong output colledor, the distortion would be increased in

47、stead of decreased. This tells us that the YEL. and GRN. leads of the driver transformer must not be inter changed and neither should the BLUE and RED leads be reversed. Some transformers had incorred color coding. A simple case of low output and distortion has resulted from one pin of one output tr

48、ansistor being bent at right angles and not in its socket; the other two pins held the transistor in place. In fadory produdion, selected pairs of transistors are used for Class “B” output. Mismatched transistors will re sult in some distortion, this may or may not be noticeable during listening. Transistors may be matched by injeding an audio signal at the volume control and measuring the audio signal from each output colledor to “ground.” Matched transistors will give matched output signal. 148 收音机爱 好者资料库 RadioFans.CN