Detailed instructions for use are in the User's Guide.
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STEREO RECEIVER
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MODELSX-3700 IN DISTINGUISHED FOLLOWS. 120V only '| 20V only 11OV 12OV , , 22OV , end 24OV(Switchabls) 11OV 12OV 22OV, and 240V (Switcha ) ble . Military mod6l
Ramarks
KU KC
e This servicemanual is applicableto the SX-3700/KU. For servicingof the other types, please refer to the additional servicemanual.
CONTENTS
1 . [. . . ] When the power is switched off, C4 is discharged rapidly via Db and R7, resulting in Q6 being tumed off and the relay contacts being opened. 410 below consists of a Wheatstone bridge with the load RL forming one of the arms. Q3 is biased by the potential difference betyyeen diametrically opposite comers of the bridge circuit. If the RL value drops below a certain fixed level, Q3 will be tumed on due to forward biasing. The charge on C4 in the relay drive circuit will thus be discharged via D3 and Q3, resulting in Q6 being tumed off and the relay contacts being opened.
If for any reason a DC voltage is generated at the output, it will be detected by the DC voltage detector circuit, resulting in the relay contacts being opened to thereby protect the speakers. Rb and C2 form a low-pass filter designed to block normal signal components, thereby preventing the application of signal voltages to the bases of Q4 and Q5. If a positive DC voltage appears at the output, it is divided by R5 and R6, and applied to Q4 and Q5. Since the base of Q5 is connected to ground, this transistor will remain off due to the reverse bias applied. And since the emitter of Q4 is connected to ground, this transistor will be tumed on due to a forward bias. Consequently, the base of Q6 is grounded by Q4, resulting in Q6 being turned off and the relay contacts being opened. If a negative DC voltage appears at the output, Q4 is tumed off due to a reverse bias, while Q5 is tumed on due to a forward bias. And since a negative voltage is applied to the emitter of Q5 in this situation, Q6 is tumed off and the relay contacts ooened.
F|ly driv circuit
F i g . 4 - 1 0 O v e r l o a d e t e c t o Ci r c u t D r i
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Powr amplifir
Overload detector circuit
DC voltag dstsctor
circuit
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AC powor supply
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R6lay driv circuit
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Fig. 4-11 Protection Circu it
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5. DISASSEMBLY
Bonnet Case Remove the four screws O on each side of the bonnet case. O to detach the
Front Panel Remove the all control knobs except push knobs. Remove the two screws tp and two nuts Q from the front panel.
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Bonnetcase
Front panel
ottom plate
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Fig. 5-1 Disassembly
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6. PARTS LOCATIONS
Front Panel
The [, mark found on some component parts indicates the importartce of the safety factor of the part. There' fore, when replacing, be sure to use parts of identical designation.
Knob (TUNING) AAA065 Front panel assembly ANB-883 Bonnet case AMM89
Push knob AAD-226
Lever knob assembly AAD-139
Front View with Panel Removed
F L assembly AWV-o12 Switch assembly GWS-233
Function switch assembly AWS-149 Lead out assembly AWVOl1
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Switch (POWER) ASA-507 P h o n ej a c k ( P H O N E S ) AKN{30 V a r i a b l e r e s i s t o r( T O N E ) ACT-127 Switch
V a r i a b l er e s i s t o r 5 O k ( V O L U M E ) 2 ACT-126 Switch (LOUDNESS) ASK. 157 Switch (MUTING) ASK-l59 V a r i a b l er e s i s t o r1 M ( B A L A N C E ) ACT{21
ASK. 157
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RearPanel
Bar-antenna ssembly a ATB24
I AC soctet (Ac OUTLETS] AKP{39
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Terminal(AM STEREOOUT) AKB{)76
Terminal (ANTENN AKAOl4 Pin iack
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AC power cord ADG{23
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Terminal(SPEAKER) AKEO44
AKB{63
Top View
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Power amp/protector assembly GWM. 159 IPower transformer ATT696 Tuner/AF assembly GWM. 160
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Detector assembly GWX463
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7. Remove the bonnet case and front panel as described in the "Disassembly" section on page 1 2. Rotate the tuning capacitor right around until the rotor blades are fully intermeshed. Secure the tuning drum back onto the tuning capacitor shaft, making sure that the securing screw I faces directly upward. Passthe cord out through the small opening in the circumference of the tuning drum (see diagram), and then take it over pulleys A, B, and C in that seouence. [. . . ] Symbol& Doscription 8111 R6 R 1 0 5 , R 1 0 6 R1 R5, R7- R93, A95 R102, A10/ R 1 0 9 , R 1 1 2 R103, R r04 Rl10 R94
ASG240 CAPACITORS
S1
Poshswiich
Symbol & Dsscriprion
C E A2 R 2 M O L s RESISTORS
c1, c2
Symbol & Doscription RDI/4PMuLilJ R D'l /2PSuirtrJ SEMICONDUCTORS Symbol& Doscription 1S1555 (1 5 2 4 7 3 )
D1 D9
R 1 R 3 , R 7 , R 8 R9
(AWV-O12) FL Assembly
CAPACITORS
Svmbol & D6scriorion
SEMICONDUCTORS
Symbol & Dsscription
cEA R47 t\, 1 50L c K D Y F 3 3 2 25 0 RESISTORS Pan No. ds beforeSymbol & Descriprion VB1, VR2 Serni-fixed R1, R2 R3, R4
N o t e . cont)erl the M54451P PD5009 HA12010 2SC45A l2sc2575l 2SA733A (2SA1r00) o1 a2 o3 05-o9, o11 024
o25 029
32
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SEMICONDUCTORS
Symbol & Doscription T A 7 3 1 8 PA HA12010 LZTS'I MZ-O41 Symbol & Doscription
o1 0 2 , 0 3
D1 D2
coMA 223J50 coMA 563J50 cor\rA 683J 50 C K D Y E1 0 3 K5 0 Noler
OTHERS
RESISTORS
Symbol & Doscription
c219, C220, C225, C226 c221 . C 3 l 2 ', 1'hen ordering resistors, conrert tlrc resistancevalue into code form, and then reurite lhe part no. [. . . ]