Sansui BA-60
Solid-State Basic Amplifier
Operating Instructions & Service Manual
Welcome to the group of proud owners of the SANSUI BA-60, a solid state stereophonic basic amplifier from the manufacturer of some of the world's finest audio components. Both in appearance and performance, the BA-60 is thoroughly professional. Not a single detail has been overlooked in designing and manufacturing the BA-60 for optimum performance, not only through numerous electrical and mechanical measurements, but by subjecting it to repeated listening tests. The end result is a moderately priced stereophonic basic amplifier without any of those weaknesses sometimes found on popular priced products. It is ideal for use in an electronic crossover system for the truest high fidelity sound reproduction ever. It is now up to you to read the instructions contained in this booklet to fully enjoy all the advanced performance capabilities built into the BA-60.
Contents
- OPERATING INSTRUCTIONS
- SWITCHES AND CONTROLS
- CONNECTIONS
- ELECTRONIC CROSSOVER SYSTEM
- HINTS ON USE
- SPECIFICATIONS/CHARACTERISTICS
- SCHEMATIC DIAGRAM
- SERVICE MANUAL
- TROUBLESHOOTING CHART
- TEST POINTS
- ADJUSTMENT
- DISASSEMBLY PROCEDURE
- PRINTED CIRCUIT SHEETS AND PARTS LIST
- OTHER PARTS AND THEIR POSITION ON CHASSIS
Switches and Controls
The front panel of the Sansui BA-60 features the following controls:
- Power Switch: Turns the unit on and off. Push once to turn on, and push again to turn off.
- Power Indicator: Lights up in orange when power is turned on, indicating the amplifier is in operation.
- Aural Null Balance Switch: Used to balance sound volumes from the right and left speakers. For balancing, feed monophonic signals to the right and left input terminals and set this switch to the 'TEST' position. After turning both LEVEL ADJUST controls to the '5' mark, turn down either control until little or no sound is heard from both speakers. Keep this switch in its 'NORMAL' position at all other times.
- Level Adjust Controls: These controls manage the sound volume for the left and right speakers independently. Turning clockwise increases volume, and counter-clockwise decreases it. The left control adjusts the left speaker volume, and the right control adjusts the right speaker volume.
- Phase Reversing Switch: Reverses the phasing (+ and -) between the amplifier and speakers. It has 'NORMAL' and 'REVERSE' positions.
Connections
Connecting Speakers
- Connect the positive (+) terminal of the left speaker to the (+) LEFT speaker terminal on the amplifier's rear panel, and the negative (-) terminal of the same speaker to the (-) LEFT speaker terminal.
- Connect the positive (+) terminal of the right speaker to the (+) RIGHT speaker terminal on the amplifier's rear panel, and the negative (-) terminal of the same speaker to the (-) RIGHT speaker terminal.
Connecting Input Sources
- Connect the left channel output of a pre-amplifier (or tuner) to the LEFT INPUT terminal on the rear of the amplifier.
- Connect the right channel output of a pre-amplifier (or tuner) to the RIGHT INPUT terminal.
Diagram Description: A block diagram illustrates the connection of input sources (TUNER, PRE-AMPLIFIER, RECORD PLAYER) to the BA-60's input terminals. The rear panel of the BA-60 is shown with labels for GND, INPUT (RIGHT/LEFT), SPEAKER SYSTEM (RIGHT/LEFT), FUSE, and PROTECTOR. It also shows the connection of speaker wires to the RIGHT SPEAKER and LEFT SPEAKER terminals. A separate diagram details how to connect a shielded cable to an A-pin plug.
Electronic Crossover System
An electronic crossover system is a sophisticated method for hi-fi sound reproduction, offering advantages over conventional crossover networks. The SANSUI BA-60 or BA-90 basic amplifier, or the SANSUI AU-777 or AU-555 amplifier, can be used in conjunction with the SANSUI CD-5 electronic crossover unit to create an electronic crossover system at a low cost. The AU-777 and AU-555 have separate pre-amplifier and basic amplifier sections that can be used independently.
Diagrams illustrate different system configurations:
- FULL-RANGE SPEAKER SYSTEM: Shows a signal path from Pre-amplifier to Basic Amplifier to a Full-Range Speaker.
- 3 WAY CROSSOVER NETWORK SYSTEM: Shows signal flow from Pre-amplifier to Basic Amplifier, then through a Crossover Network to Tweeter, Midrange, and Woofer speakers.
- TRI-AMPLIFICATION ELECTRONIC CROSSOVER SYSTEM: Depicts a system where a Pre-amplifier feeds an Electronic Crossover Unit, which then sends signals to separate Basic Amplifiers (for High Range, Mid Range, Low Range), each driving a specific speaker type (Tweeter, Midrange, Woofer).
Using the BA-60
To set up an electronic crossover system using the BA-60, connect the outputs of a pre-amplifier to the input terminals of the SANSUI CD-5 electronic crossover unit. The CD-5 divides signals into high, medium, and low frequency ranges (or channels). Subsequently, connect three BA-60s (or BA-90s), or a combination thereof, to the separate output terminals of the CD-5. Each BA-60 then feeds its amplified signal to an individual speaker, such as one BA-60 for the high-frequency range to a tweeter, another for the mid-range, and a BA-90 for the low-frequency range to a woofer.
Hints on Use
Voltage Change-over Plug
The BA-60 allows voltage selection for its power supply circuit via a plug that can be shifted among four positions: 100V, 117V, 220V, and 240V. Ensure the plug is set to the correct voltage for your area by inserting it so the arrow mark aligns with the desired voltage indication.
Should the Power Fuse Blow...
If the amplifier fails to operate due to a blown fuse, unplug the power cord and replace the fuse with a new, glass-tubed 2-ampere fuse. Using wire or a fuse of a different capacity is dangerous and can cause serious trouble. If the fuse blows repeatedly, it indicates a problem within the amplifier that needs to be identified and resolved before replacing the fuse.
Should the Protector Operate...
The BA-60 is equipped with a circuit breaker (protector) to safeguard its silicon power transistors. If the output circuit is short-circuited or an overcurrent flows, the protector activates, stopping sound output to the speakers. This can also occur due to momentary overcurrent. If no sound is heard after turning on the power, the protector has likely operated. Turn off the power immediately, wait about 5 seconds, and then push the red protector restoring buttons on the rear of the amplifier. If the amplifier still fails to operate normally, turn off the power again and check speaker terminals and cords for short-circuits. If the problem persists, contact a SANSUI dealer.
Heat Radiation
Transistors are sensitive to heat. The BA-60 is designed for effective heat dissipation through its bonnet. Avoid placing objects on top of the amplifier, encasing it in a tight cabinet, or operating it in direct sunlight, as these can lead to breakdown. If such conditions are unavoidable, take measures to increase heat dissipation.
AC Outlet
The amplifier's rear panel features an AC outlet with a maximum capacity of 150VA, intended for powering other audio components like pre-amplifiers. Connecting components with higher power requirements is dangerous and may cause the amplifier to break down.
Grounding
To ground the amplifier, connect one end of a wire (PVC or enameled) to the GND terminal on the left side of the rear panel. Attach a small copper plate to the other end and bury it deep underground. Grounding typically reduces noise. If using the BA-60 with a phonograph, tuner, or tape recorder, connect their grounding wires to the GND terminal to reduce hum. Ensure the power cord is removed from the wall outlet when making grounding connections.
Should the Speaker Polarities Differ...
If speakers are connected with reversed polarity, the reproduced sound will be weak, particularly in the bass response. This is noticeable on monophonic sources. To correct this, use the 'PHASE' switch on the amplifier and set it to the 'REVERSE' position. Once matched, the speakers will sound as if producing sound from a single central source.
Make Proper Connections
Ensure all lead wires from input and output components are securely connected to the respective terminals. Loose connections or wires touching other parts can lead to malfunction, noise, or long-term damage. Connect other components, such as phonographs or tape recorders, according to their manufacturer's instructions.
Diagram Description (Shielded Cable): A diagram shows the process of connecting a shielded cable to an A-pin plug, involving removing a pin plug cover, inserting the cable, soldering, and replacing the cover.
Specifications/Characteristics
| Specification | Value |
|---|---|
| RATED POWER OUTPUT (MUSIC POWER, IHF) | 60W (4 ohms) / 50W (8 ohms) |
| RATED POWER OUTPUT (CONTINUOUS POWER) | 25W/25W (4 ohms) / 20W/20W (8 ohms) |
| TOTAL HARMONIC DISTORTION | Less than 0.3% |
| INTERMODULATION DISTORTION (60Hz:7,000Hz=4:1) | Less than 0.5% |
| POWER BANDWIDTH (IHF) | 20~40,000Hz (8 ohms) |
| FREQUENCY RESPONSE | 20~60,000 Hz ±1dB (8 ohms; at rated output) |
| INPUT SENSITIVITY | 0.7V per 1,000Hz input required to deliver rated continuous output |
| INPUT IMPEDANCE | More than 50k ohms |
| LOAD IMPEDANCE | 4~16 ohms |
| DAMPING FACTOR | Over 46 (8 ohms) |
| HUM AND NOISE (IHF) | Better than 80 dB |
| CHANNEL SEPARATION | Better than 50dB |
| CIRCUIT COMPLEMENT | 13 transistors (2SD247 x 4, 2SC734 x 4, 2SA561 x 2, 2SD247 x 2, CDC8002-1 x 1), 1 diode (15-1850), 4 varistors (DS-410 x 4) |
| POWER VOLTAGE | 100V, 117V, 220V, 240V AC, 50/60Hz |
| POWER CONSUMPTION | 100VA (max.) |
| DIMENSIONS | 6"W x 4-3/8" H x 10-3/8" D |
| WEIGHT | 9.2 lbs. |
* All rights reserve specifications subject to change without notice.
Graphs Description:
- POWER BANDWIDTH CHARACTERISTIC: Illustrates frequency response (in dB) across various frequencies (Hz) at different output levels.
- MUSIC POWER CHARACTERISTIC: Shows output power (W) versus frequency (Hz) for an 8-ohm load.
- INTERMODULATION DISTORTION CHARACTERISTIC: Displays intermodulation distortion percentage against output power (W) for an 8-ohm load.
- TOTAL HARMONIC DISTORTION CHARACTERISTIC: Presents total harmonic distortion percentage against output power (W) at specific frequencies (40Hz, 1kHz, 20kHz) for an 8-ohm load.
Schematic Diagram
A schematic diagram is provided, detailing the internal electronic circuitry, component layout, and connections within the amplifier.
Troubleshooting Chart
A Quick Check List: Before troubleshooting, verify the following:
- Connections: Are all components properly connected to the amplifier? Is the amplifier plugged into the wall AC outlet?
- Operation: Are you operating the amplifier correctly as per the instructions?
- Installation: Is the amplifier properly positioned relative to speakers and phonograph?
- Defective components: Are any connected audio components defective?
- Performance characteristic: Are you placing an excessive strain on the amplifier to achieve a particular performance characteristic?
Troubleshooting Table
| PROGRAM | SYMPTOM | PROBABLE CAUSE | REMEDY |
|---|---|---|---|
| Radio broadcast | Constant or intermittent noise heard at certain hours or in a certain area. | Electric discharge or oscillation from fluorescent lamps, TVs, motors, electrical contacts, rectifiers, oscillators, etc. Insufficient antenna input due to long distance from broadcast stations or signal obstruction by mountains or high ferro-concrete buildings. Interference by other radio waves. Natural phenomena such as atmospheric discharge and lightning. | Attach a noise suppressor to the tuner or the electrical appliance producing the noise. Place the tuner away from the electrical appliance producing the noise. Install an outdoor antenna and ground the amplifier to improve its S/N ratio. If noise occurs at a certain frequency, attach a wave trap to the antenna input circuit of the tuner. Reverse the inserted position of the power cord plug. |
| Radio broadcast (cont'd) | Noise heard on AM band at certain hours, in a certain area or at particular broadcast frequencies. | Insufficient signal strength. | Install an outdoor AM antenna, or if already installed, reposition it for best reception. Ground the amplifier and/or reverse the inserted position of the power cord plug. |
| Radio broadcast (cont'd) | High-frequency noise. | Interference by adjacent channel (beat interference). | While noise due to such causes cannot be eliminated by adjusting the amplifier, it can be made less disturbing by turning down the TREBLE tone control or turning on the HIGH filter switch on the preamplifier. Move the amplifier away from the TV set. |
| Radio broadcast (cont'd) | FM broadcast reception is noisy. | Poor noise limiter effect and lowered SN ratio due to insufficient antenna input, resulting either from poorly positioned FM antenna or long distance from stations. | Re-position the FM antenna for the least noise and best reception. If this proves ineffective, install an exclusive outdoor FM antenna and position it for the best reception. |
| Radio broadcast (cont'd) | NOTE: Quality of FM broadcast reception is largely affected by the transmitting conditions (such as antenna efficiency) of broadcast stations. So you may receive one station quite well while having difficulty in receiving another. | TV antenna may be shared for FM broadcast reception, but be sure to use a divider and make certain the TV reception is not affected. Excessively long antenna may increase noise. | |
| Radio broadcast (cont'd) | Scratchy noise on FM band. | Ignition noise made by the starting of a nearby automobile engine (particularly loud near 15MHz on dial scale). | No effective remedy except to move the antenna as far away from the street as possible or increase the antenna input as instructed above. Position the antenna so as to maximize the antenna input. |
| Radio broadcast (cont'd) | Noise heard with FM MPX broadcasts that was not heard with FM monophonic broadcasts. | Unavoidable because of the nature of FM MPX signals which cut down effective service area to half that of FM monophonic signals. | Turning on HIGH FILTER switch and/or turning down TREBLE tone control may considerably reduce the noise. |
| Record and tape | Hum or howling | Phonograph is placed on top of or near one of the speakers. Use of wire other than shielded wire. Incomplete connection. Connection cord too close to power cord and/or electrical appliances such as a fluorescent lamp. Existence of an amateur radio station or TV transmitting antenna in the vicinity. | Place a cushion underneath the phonograph. Try changing the location of the phonograph and speakers. Use regular shielded wire to make interconnections. Turning on LOW FILTER switch may help. Minimize the length of connection cord. Refrain from turning up BASS tone control too high. Consult your nearest governmental (or municipal) radio regulatory office. |
| Record and tape (cont'd) | Surface noise. | Worn or damaged record, or dust on record. Worn stylus, or dust on stylus. Improper stylus pressure. | Turning down TREBLE tone control or turning on HIGH FILTER switch may help. Recondition (or replace) the phonograph stylus or tape head. |
| All programs | BALANCE control is off the center position when sound volumes in the right and left channels are balanced. | Position of the BALANCE control which gives equal sound volume from both channels varies from program to program. | Set the preamplifier's MODE switch in MONO and adjust its BALANCE control for equal sound volume from both channels. Or make more precise adjustment using the AURAL NULL BALANCE switch on this amplifier. Check if the efficiency of one speaker is balanced with that of the other. |
Alignment
Test Points
The test points for one of the stereo channels are indicated here. Test points also exist at the same positions on the corresponding printed circuit sheet for the other channel. Labels such as CB001, CB002, VR801, and VR802 are shown on a diagram of the circuit board.
Output Adjustment
- Turn down variable resistors VR801 and VR802 to a minimum.
- Set audio oscillator at 1,000Hz and connect it to the left (right) channel INPUT terminal.
- Connect an 8 or 16 ohm resistor with a capacity of more than 50W to the left (right) channel speaker terminal.
- Connect an oscilloscope to the speaker terminal.
- Turn on power, raise volume slowly, and confirm on the oscilloscope that there is output at the speaker terminal.
- Adjust VR801 for the left channel so that both peaks of the output waveform (sine wave) will be clipped simultaneously. Make a similar adjustment with VR801 for the right channel.
Current Adjustment
- Insert a 16 ohm resistor between the upper terminal of CB001 and CB002 and earth to see if CB001 and CB002 operate. If they operate, remove the resistor.
- Turn down VR801 and VR802 to a minimum.
- Turn on the power switch.
- Connect the lower terminal of CB001 to the (+) terminal of the ammeter, and the upper terminal to its (-) terminal.
- Adjust VR802 on the left channel PC board so that the ammeter indicates 14 to 18mA if room temperature is below 25°C, and 18 to 22mA if it is over 25°C.
- Connect the lower terminal of CB002 to the (+) terminal of the ammeter, and the upper terminal to its (-) terminal.
- Adjust VR802 on the right channel PC board so that the ammeter indicates 14 to 18mA if room temperature is below 25°C, and 18 to 22mA if it is over 25°C.
- Push both red protector restoring buttons (for CB001 and CB002) on the amplifier's rear panel.
Disassembly Procedure
An exploded view diagram illustrates the procedure for disassembling the unit, showing how to access internal components by removing the chassis and front panel.
Printed Circuit Sheets and Parts List
DRIVER AMP. BLOCK
| X: Parts No | Y: Parts Name | Z: Position of Parts |
|---|---|---|
| R801 | 10kΩ ±10% 1/2W Solid Resistor | 1 A |
| R802 | 150kΩ ±10% 1/2W Solid Resistor | 2 A |
| R803 | 560kΩ ±10% 1/2W Solid Resistor | 1 A |
| R804 | 220Ω ±10% 1/4W Carbon Resistor | 2 A |
| R805 | 3.3kΩ ±10% 1/2W Solid Resistor | 2 A |
| R806 | 2.7kΩ ±10% 1/2W Solid Resistor | 1 A |
| R807 | 18kΩ ±10% 1/2W Solid Resistor | 1 B |
| R808 | 4.7kΩ ±10% 1/2W Solid Resistor | 2 A |
| R809 | 10Ω ±10% 1/2W Solid Resistor | 2 B |
| R810 | 15kΩ ±10% 1/2W Solid Resistor | 2 A |
| R811 | 220Ω ±10% 1/2W Solid Resistor | 2 A |
| R812 | 3.9kΩ ±10% 1/2W Solid Resistor | 1 B |
| R814 | 330Ω ±10% 1/2W Solid Resistor | 2 B |
| R815 | 220Ω ±10% 1/2W Solid Resistor | 2 B |
| R817 | 33Ω ±10% 1/2W Solid Resistor | 2 B |
| R818 | 220Ω ±10% 1/2W Solid Resistor | 1 B |
| C801 | 0.22μF ±10% 50WV Mylar Capacitor | 1 A |
| C802 | 47 pF ±10% 50WV Ceramic Capacitor | 1 A |
| C803 | 100μF 10WV Electrolytic Capacitor | 2 A |
| C804 | 4.7 µF 50WV Electrolytic Capacitor | 1 A |
| C805 | 10μF 25WV Electrolytic Capacitor | 2 B |
| C806 | 0.04µF ±10% 50WV Mylar Capacitor | 2 B |
| C807 | 100μF 10WV Electrolytic Capacitor | 2 A |
| C808 | 33μF 50WV Electrolytic Capacitor | 1 A |
| C809 | 300 pF ±10% 50WV Ceramic Capacitor | 2A |
| C810 | 33μF 50WV Electrolytic Capacitor | 2 A |
| TR801 | 2SC649 (0305091) | 1A |
| TR802 | 2SC734 (030536) | 1A |
| TR803 | 2SC734 (030536) | 1 B |
| TR804 | 2SA561 (030010) | 2 B |
| D3 | DS-410 (031046) | 1 B |
| D4 | DS-410 (031046) | 1 A |
| VR801 | 500kΩ (Β) AC Balance Adjustor (103050) | 1A |
| VR802 | 200Ω(B) DC Bias Adjustor (103012) | 1 B |
A diagram shows the layout of components on a printed circuit board for one stereo channel, with labels for resistors, capacitors, transistors, and variable resistors.
Other Parts and Their Position on Chassis
| X: Parts No | Y: Parts Name |
|---|---|
| R001 | 560Ω ±10% 1/2W Solid Resistor |
| R002 | 560Ω ±10% 1/2W Solid Resistor |
| R003 | 0.5Ω ±10% 3W Cement Resistor |
| R004 | 0.5Ω ±10% 3W Cement Resistor |
| R005 | 0.5Ω ±10% 3W Cement Resistor |
| R006 | 0.5Ω ±10% 3W Cement Resistor |
| R008 | 1.5kΩ ±10% 1/2W Solid Resistor |
| R009 | 1.5kΩ ±10% 1/2W Solid Resistor |
| R010 | 10kΩ ±10% 1/4W Carbon Resistor |
| C001 | 0.0022µF ±20% 60WV Oil Capacitor |
| C002 | 0.0022µF ±20% 60WV Oil Capacitor |
| C003 | 2200μF 63WV Electrolytic Capacitor (020541) |
| C004 | 2200μF 35WV Electrolytic Capacitor (020542) |
| C005 | 2200μF 35WV Electrolytic Capacitor (020542) |
| C006 | 0.047μF ±10%400WV Oil Capacitor |
| C007 | 0.047μF ±10%400WV Oll Capacitor |
| C008 | 100μF 75WV Electrolytic Capacitor |
| VR001 | 100kΩ (Β) 244 Level Adjustor (100022) |
| VR002 | 100kΩ (Β) 244 Level Adjustor (100022) |
| D001 | IS-1850 (031053) |
| CB001 | Circuit Breaker (190001) |
| CB002 | Circuit Breaker (190001) |
| TR805 | 2SD247 (030819,-1) |
| TR806 | 2SD247 (030819,-1) |
| TR807 | 2SD247 (030819,-1) |
| TR808 | 2SD247 (030819,-1) |
| TR001 | CDC 8002-1 (030555,-1,-2) |
| S1 | Aural Null Balance Switch (117009) |
| S2 | Phase Switch (117009) |
| S3 | Phase Switch (117009) |
| S4 | AC Power Switch (113009) |
| PU001 | Voltage Selector Switch (241008/241009) |
| F001 | 2A Fuse (043003) |
| C0001 | AC Outlet (245001-1) |
| T001 | Power Transformer (400037) |
| PL1 | 8V 150mA Pilot Lamp (040005) |
An image shows the internal layout of the amplifier with various components labeled, including F001, C002, CB001, C006, TR805, TR806, D001, C003, PU001, C001, CO001, S4, PL1, CB002, C004, TR807, R001, R002, TR808, C005, C007, T001, VR001, VR002.
Manufacturer Information
SANSUI ELECTRIC COMPANY LIMITED
Head Office: 14-1, 2-chome, Izumi, Suginami-ku, Tokyo, Japan. TEL. 323-1111
Printed in Japan (41500M3)
