Marantz-105B-tun-sm维修电路原理图.pdf

SERVICE MANUAL RadioFans.CN 收音机爱 好者资料库 .;i/L TABLE OF CONTENTS SECTION PAGE Introduction . 1 AM Tuner. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 FM Tuner. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 AM Alignment Procedure . 3 FM Alignment Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Test Equipment Required for Servicing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Parts List . 13 17 Technical Specifications . .18 LIST OF ILLUSTRATIONS FIGURE PAGE 1. Dial Stringing . 5 2. Front Panel Adjustments and Component Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Main Chassis Component Locations (Top View) . 6 4. Rear Panel Adjustment and Component Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5. Main Chassis Component Locations (Bottom View) . 7 6. FM/AM Tuner Assembly P100 Component Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7. FM, AM, Mono and Muting Switch Assembly P300 Component Locations. . . . . . . . . . 8 8. Power Supply Assembly P400 Component Locations . 8 9. Schematic Diagram . 9, 10 10. Exploded Mechanical Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11, 12 TABLE 1. Test Equipment Required for Servicing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 RadioFans.CN 收音机爱 好者资料库 INTRODUCTION This service manual was prepared for use by Authorized Warranty Stations and contains service information for Marantz Model l 05B Stereophonic Tuner. Servicing information and voltage data included in this manual are intended for use by the knowledgeable and experienced technician only. All instruction should be read carefully. No attempt should be made to proceed without a good understanding of the operation in the t uner. The part lists furnish information by which replacement part may be ordered from the Marantz Company. A simple description is included for parts which can be usually be obtained through local suppliers. The Model 1058 is a tuner version of the Marantzs Model 2015 Tuner/Amplifier and almostthe same circu itry as used in the Model 2015 is employed except the audio Amplifier, and power supply circuit. 1. AM Tuner A ll components except ferrite bar antenna are mounted on a printed circuit board Pl00. The AM signals induced in a ferrite bar antenna are applied to the base of converter transistor H113 t hrough a capacitor of C171, while t he local oscillator voltage is injected to the emitter of H113 t hrough a capacitor C172. Both AM signals and oscillating voltage are mixed at the base-emitter junction and converted into 455KHz intermediate frequency. The resulting I F signal is applied to the f irst I F transformer L 116 consisting of one ceramic filter and two tuned circuits. The output of L11 6 is led to the transistor H 1 04 which in turn apply its output to the transistor of next stage Hl05. The fully amplified IF output is then applied to the diode H123 to detect audible signal through the detector transformer L 117. The detected audio signal is filtered and the final audio output is obtained from pin terminal J118 and applied: to the output jacks through the funct ion switch. The DC component of the detected I F signal is used as a AGC voltage to control emitter current of H 104 through the resistor R 185. A part of I F signal output is also applied to the diode H124 through a capacitor C1BO and rectified to obtain DC current for energizing the AM signal strength meter M001. 1.1 Suggestions for AM Tuner trouble shooting Check for broken A M bar antenna, next try to tune station by rotating fly-wheel tuning knob slowly and observe the AM signal strength meter whether it deflects or not. If the signal strength meter gives a deflection at several frequencies received, no failure may exist in the stages at least preceding final I F transformer L 117. Next connect a oscilloscope to the pin terminal J118 and check for audio signals with the tuning meter deflected. If the signal strength meter does not deflect, check the local oscillator circuit. Normal oscillating voltage at the hot end of the oscillator tuning capacitor is about 2 or 3 volts, varying with tuning capacitor position. When measuring oscillating voltage use a RF VTVM, no circuit tester gives correct indication. Ifthe local oscillator voltage is normal, check all voltage distribution in the AM circuits by using a DC VTVM and compare the measured values with those given in the schematic diagram. 2. FM Tuner All components are mounted on a printed circuit board P100. FM signals induced by a FM antenna are led to FM antenna coil L 101. These signals are then applied to the FET RF amplifier which in turn applies its output to the next transistor mixer Hl02 through a high Q tuned circuit. The mixer convert its input signal into 10.71V1Hz intermediate frequency and amplifies it at the same time. The H103 is a local oscillator and its output is injected into the base of mixer transistor, the inject ion voltage is about 40mV. 1 RadioFans.CN 收音机爱 好者资料库 - - -.:.:. The 10.7 MHz front end output is led to the next IF section . The IF section consists of five stage of I F amplifier and one stage of sub I F amplifier. Two pieces of ceramic filters are also used to obtain high selectivity, a pair of symmetrical diode limiters are also employed for the best limiting characteristics, improved capture ratio and good AM suppression. A part of I F amplifier H 1 05 output is rectified by the diode H 115, H 116 and its DC output is fed back to the gate of FET RF amplifier to decrease the gain with increased signal strength. 2.1 Muting and Auto-Stereo Switching Circuits The muting circuit consisting of all solid-state electrical switching has been incorporated in the Mode1105B. The DC vo Itage obtai ned by rectifing the su b I F output signal from the H109 is app I ied to the base of H11 0 and turns on it, if the sub I F output is greater than predetermined level (muting threshold level). When H110 turns on, the muting switch transistor H111 is turned on, thus decreasing the emitter collector resistance to near zero ohm and allowing emitter current path to the Final IF amplifier H1 08. When the input signal is lower than the predetermined level, the DC output obtained is small and can not turn on the H110, thus the H110 keeps its turn off state and this makes the switch transistor keep H111 turn off, then no emitter current is supplied to the H108 and signals below the threshold level are muted out. The muting threshold level can be varied by adjusting the trimming resistor R 153. The DC voltage obtained is also used to make the Auto-Stereo switching transistor H112 turn on and off. 2.2 MPX Stereo Decoding Circuit A Non-equalized audio signal from the FM detector is applied through the phase adjuster network of C148 and R161 to input terminal pin CD on the MPX decoder IC Hl14. The MPX decoder Ie consists of a stereo decoder and postamplifier for the output. The right and left channel signals decoded by the stereo decoder H11 4, appear at pin (right channel) and pin QJ) (left channel), respectively. These signals are passed through the low-pass filters and de-emphasis networks to eliminate undesirable residual switching signals and are then delivered to postamplifier input pin (right channel) and pin (j) (left channel), respectively. The signals ampl ified in the postamplifiers to the required level (approximately 10 dB) are delivered to pin (right channel) and pin (left channel), and are then passed through C169 and C168 to pin terminals Jl14 and Jl15, hence, through fu nction switches to the OUTPUT terminal. Pin (j) on the MPX IC Hl14 is connected through R163 to the collector of the autostereo switch transistor Hl12, which turns on or off according to the incoming FM signal strength, thereby automatically switching between the stereophonic and monaural operations. The H112 turns on or off in accordance with whether the FM signal strength is more or less than approximately 25V. 2.3 Suggestion for Trouble Shooting of FM Tuner 2.3.1 Symptom: No FM Reception First turn on the power switch and try to tune FM stations. Rotate the fly-wheel tuning knob slowly and observe the FM TU NING meter. If the TUNING meter deflect at several frequencies received, the tuner circuits preceding the discriminator circuit may have no failure. When no reading is obtained in the meter, check FM local oscillator circuit, using a RF VTVM. The normal local oscillator voltage is one or two volts (rms) at the tuning capacitor, depending on the tuning capaCitor position. If the local oscillator voltage is normal, next check all voltage distribution in the FM Front End and I F amplifier unit and compare them with those shown in the circuit diagram. When TUN I NG meter deflects but no sound is obtained, check audio circuits, using high sensitive oscilloscope. 2 RadioFans.CN 收音机爱 好者资料库 2.3.2 Symptom: No Stereo Separation First check the MONO switch is in normal out position. Connect a FM R F signal generator output modulated by a stereo modulator to the rear FM antenna terminals, and check the stereo beacon is turned on or not. If not turned on, check for 19 KHz pilot signal and 38 KHz switching signal, usi,ng an oscilloscope. 3. AM Alignment Procedure 3.1 AM I F Alignment 1. Connect a sweep generator to the test point or J 1 07 and an alignment scope to the test point . 2. Rotate each core of I F transformer L116 and L117 for maximum height and flat top symmetrical response. 3.2 AM Frequency Range and Tracking Alignment 1. Set AM signal generator to 525 KHz. Turn the tuning capacitor fully closed (place the tuning pointer at the low end.) and adjust the oscillator coil L 115 for maximum audio output. 2. Set the signal generator to 1650 KHz. Place the tuning pointer in the high frequency end and adjust the oscillator trimmer on the oscillator tuning capacitor (CA-2) for maximum audio output. 3. Repeat the step 1 and 2 until no further adjustment is necessary. 4. Set the generator to 600 KHz and tune the receiver to the same frequency and adjust a slug core of AM ferrite rod antenna for maximum output. 5. Set the generator to 1400 KHz and tune the receiver to the same frequency and adjust the trimming capacitors of Antenna (CA-1) for maximum output. 6. Repeat the step 4 and 5 until no further adjustment is necessary. Note: During tracking alignment reduce the signal generator output as necessary to avoid AGC action. 4. FM Alignment Procedure 1. Connect a FM signal generator to the FM antenna terminals and a oscilloscope and an audio distortion analyzer to the tape output jacks on the rear panel. 2. Set the FIVI SG to 87.5 MHz and provide about 3 to 5 J.lV. Place the tuning pointer at the low frequency end by rotating the tuning knob and adjust the core of oscillator coil L 103 to obtain maximum audio output. 3. Set the FM SG to 108.5 MHz and provide about 3 to 5 J.lV output. Rotate the tuning knob and place the tuning pointer at the high frequency end and adjust the trimming capacitor C187 for Maximum output. 4. Repeat the step 2 and 3 until no further adjustment is necessary. 5. Set the FM SG to 90 MHz and tune the receiver to the same frequency. Decrease signal generator output until the audio output level decreases with the decreasing generator output. Adjust the antenna coil L101, RF coil L102 and IF transformer L105 for minimum audio distortion. 6. Set the FM SG to 106 MHz and tune the receiver to the same frequency. Adjust the trimming capacitor CF-l, CF-2 for minimum distortion. 7. Repeat the step 5 and 6 until no further adjustment is necessary. 8. Connect a DC VTVM with 0.5 volt range selected to the test point (J120) and adjust the secondary core (upper) of discriminator transformer L 107 so that no voltage reading is obtained on the VTVM at no signal. Next set the FM SG to 98 MHz and increase the output level to 1 KJ.lV, then tune the receiver to the same frequency so that no deflection is obtained on the VTVM. Adjust primary core (bottom) of L 107 for minimum distortion, and adjust the L 108 for the maximum reading on the VTVM connected to the J109. RadioFans.CN 收音机爱 好者资料库 ._- -. . 4.1 STEREO Separation Alignment 1. Set the FM SG to provide 1 K/-lV at 98 MHz. Tune the receiver to the same frequency perfectely (so that the VTVM connected to the test point gives no reading) . 2. Modulate the FM SG with stereo composite signal consisting of subchanged signal only (of course a pilot signal must be included). Adjust the core of L 110 for maximum audio output, then, modulate the FM SG with a stereo composite signal consisting of L or R channel only, and adjust the trimming resistor R 161 for maximum and equal separation in both channels. 4.2 Muting Circuit Alignment 1. Set the FM SG output to provide 25 /-lV (lHF) at 98 MHz and tune the receiver to the same frequency. Adjust the trimming resistor R153 for the threshold level of 25 /-lV (during this adjustment turn the MUTING pushswitch on). 5. Test Equipment Required for Servicing Table 1 lists the test equipment required for servicing the Model 105 B Tuner. Item Manufacturer and Model No. Use AM Signal Generator Signal source for AM align ment Test Loop Used with AM Signal generator I FM Signal Generator Less than 0.3% distortion Signal source for FM align ment Stereo Modulator Less than 0.3% distortion Stereo separation alignment and trouble shooting Audio Oscillator I Weston Model CVO-l00P, less than 0.02% residual distor tion is required Sinewave and squarewaves sig nal source Oscilloscope High sensitivity with DC hori zontal and vertical amplifiers Waveform analysis and Trou ble Shooting, and ASO align ment VTVM With AC, DC, R F range Voltage measurements Circuit Tester Trouble Shooting Table 1. Test Equipment Required for Servicing 4 RadioFans.CN 收音机爱 好者资料库 56 POINTER Figure 1. Dial Stringing 5 RadioFans.CN 收音机爱 好者资料库 .-.-. /A ,_C- wnod. I . ion SOOl Figure 2. Front Panel Adjustments and Component Locations 1-P400 -l02 Figure 3. Main Chassis Component Locations (Top View) 6 RadioFans.CN 收音机爱 好者资料库 JO 3 LOOt J012 Figure 4. Rear Panel Adjustment and Componen