Toshiba SM 3750 Service Manual

Page 2

SM -3750 I

CONTENTS
1. OPERATING CONTROLS ................ .
RECEIVER SECTION ........................................
CASSETTE RECORDER SECTION ............................... 4
TURNTABLE SECTION ........ . . . . 4
2. DISASSEMBLY INSTRUCTIONS ............................... 5 ~ 6
TURNTABLE REMOVAL ..................................... 5
CASSETTE RECORDER PANEL REMOVAL ........................ 5
CABINET REMOVAL ........................................ 6
FRONT PANEL REMOVAL .................................. 6
3. ADJUSTMENT INSTRUCTIONS .............................. 7 ~ 13
RECEIVER SECTION .................................... 7 ~ 10
CASSETTE RECORDER SECTION ........................... 11 ~ 12
TURNTABLE SECTION ...................................... 13
4. DIGITAL CLOCK OPERATION ............................... 14 ~ 16
DIGITAL CLOCK SECTION ................................... 14
DIGITAL CLOCK OPERATION ................................. 14
TIME ADJUSTMENT PROCEDURE .............................. 15
SAFETY DEVICE ........................................... 16
5. DIAL CORD STRINGING ....................................... 17
6. P.C. BOARD PARTS LOCATION AND SCHEMATIC DIAGRAMS ....... 17 ~ 24
DIGITAL CLOCK P.C. BOARD/SCHEMATIC
DIAGRAM (CLOCK SECTION) ............................. 17 ~ 18
CASSETTE RECORDER P.C. BOARD ............................ 19
SCHEMATIC DIAGRAM (CASSETTE RECORDER SECTION) ............ 20
TUNER P.C. BOARD ........................................ 21
SCHEMATIC DIAGRAM (TUNER SECTION) ....................... 22
AUDIO AND POWER P.C. BOARD .............................. 23
SCHEMATIC DIAGRAM (AUDIO AND POWER SECTION) ............. 24
7. SCHEMATIC DIAGRAM (OVERALL) ............................... 25
WIRING AND SCHEMATIC DIAGRAM ............................. 26
TURNTABLE SECTION ...................................... 26
9. EXPLODED VIEW ............................ . . .27 ~ 29
CABINET SECTION ......................................... \27
TURNTABLE SECTION ...................................... 28
CASSETTE RECORDER SECTION ............................... 29
10. PARTS LIST ............................................ 30 ~ 38
CAUTION '

Take care to avoid static electricity as it can easily damage the LSI (TM51943N L) used in model SM-3750.
1, Never touch the terminal of LSI with bear fingers.

2. Never bring the terminal of LSI into contact with other materials.

3. Use the LSI getting in conductive foam rubber.

4. When using a soldering iron, it is recommendable to connect it to the ground.

*Noise Reduction System is manufactured under license from Dolby Laboratories Inc. Dolby" and the double-D
symbol are trademarks of Dolby Laboratories Inc.

Page 6

3. ADJUSTMENTS INSTRUCTIONS

3~1 RECEIVER SECTION
I ADJUSTING PARTS LOCATION

L0: L04

mw

PM Front End
0 o 00
FM 1F hour
0 o
Imzumironpm 5::
..

:49. 57
Vermin. capaciior

W" ha-F w
museum) 0 O [
hi]
FMl MlNl

VRZ
MIMMlNl

FMiMAXl
El VRIOS

cn C45 cisi

ISW

L02

Figure 13. Top View of Tuner P.C. Board

I TEST EQUIPMENTS/TOOLS REQUIRED

1. Sweep signal generator (Sweep range of at least 300 kHz, centre frequency of 10.7 MHz.)

2. Signal generator with a frequency range of at least from 400 kHz to 19 MHZ for AM, from 87 MHz to

110 MHz and 10.7 MHZ for FM.

I SM-3750 SM-3750 l

l LW ADJUSTMENT

1. Set Function switch to LW.
2. Set signal generator frequency as listed in TABLE 1 LW ADJUSTMENT CHART.
3. Proceed as outlined in the TABLE 1 LW ADJUSTMENT CHART.

TABLE I LW ADJUSTMENT CHART (See Figure 14)

3. Oscilloscope with a wide range amplifier of approximately 100 kHz.
. Test loop - a coil of any size wire with one turn or more.
5. VTVM (Vacuum tube voltmeter)

as

NOTES: 1. During alignment keep the signal generator output at the lowest level where useable signal output
from the set can be maintained.
2. Ground connection of signal generator ----- To chassis ground.
3. Generator modulation ----- 400 Hz, 30%.
4. For alignment points, see schematic diagram.

_7_

Signal Signal Radio Co t'
Step Generator Generator Dial nnec ion Adjustment Remarks
. , (See fig. 14.)
Connection Frequency Setting
Tuning gang VTVM across lT03 .
1 Test loop 460 kHz fully counter- Speaker lTO4 3(1)::5:
clockwise terminal ITOS a
T ' .
2 Test loo 142 kHz fuullnIZiugrifir- \S/ZZIEZracross L03 AdJUSt for
p y . p . LW osc. Maximum
clockWIse terminal
T .
3 Test loop 410 kHz fuliiung gang gzzxracmss C60 Adjust for
y . p . OSC. Trim. Maximum
clockwrse terminal
4 Repeat steps 2 and 3 until no further improvement is noticed.
VTVM across
5 Test loop 180 kHz Time to Speaker L01 (Um Adj? for
Signal terminal Ant. COII Maxrmum
VTVM across '
6 Test loop 380 kHz Tune to Speaker C47 . AdLiSt for
Signal terminal Ant. Trim. MaXImum
7 Repeat steps 5 and 6 until no further improvement is noticed.
I MW ADJUSTMENT
1. Set Function switch to MW.
2. Set signal generator frequency as listed in TABLE 2 MW ADJUSTMENT CHART.
3. Proceed as outlined'in the TABLE 2 MW ADJUSTMENT CHART.
TABLE 2 MW ADJUSTMENT CHART (See Figure 14.)
Signal Signal Radio .
Step Generator Generator Dial Conn:ctii:: ) Adjustment Remarks
Connection Frequency Setting (See '9
1 T I 455 kHz/ :ir'ng gang :Tvy across L04 Adjust for
e 9 460 kHz V Wm" 9. 9 MW 030. Maximum
clockWise terminal
T i 1650 kH running gang :TVC across €63 Adiumm
2 est oop z u y , pea. er MW Trim. Maximum
clockwrse terminal
3 Repeat steps 1 and 2 until no further improvement is noticed.
Tune to VTVM across L01 (MW) Adjust for
4 Test loop 600 kHz signal Teprfgifiarl Ant. CO Maximum
Tune to VTVM across C48 Adjust for
5 Test IOOP 1400 kHz signal Sgenakneg MW Trim. Maximum
6 Repeat steps 4 and 5 until no further improvement is noticed.

WNW...