The TCS-310 is a stereo cassette recorder (Magnetophone Cassette Stereo) manufactured by the Sony Corporation in Tokyo Japan. This is a 4-track 2-channel Stereo Cassette-Corder measuring 93.5 mm × 161.5 mm × 41 mm in size and weighing 560 g with batteries. It requires four “AA” sized batteries, providing 6 V, or it can receive power through a mains adapter AC-15A available as an accessory.
This cassette recorder is very much the holy grail of the early Walkmans. The cue and review buttons, and mono (320 mW) output through a 5 cm speaker, indicate that this machine inherits its design from the early dictation machines. In that respect, it has a well tried and tested tape transport mechanism, taken from earlier designs, and all that they have done is change the circuitry to provide stereo recording and playback capability. What is remarkable about this unit is the fast forward and rewind functions, which utilise a cogwheel mechanism, instead of rubber belts and surfaces, which would have worn out by now.
The circuitry utilises the TA7658P integrated circuit (IC) by the Toshiba Corporation, which is a dual preamplifier providing recording and playback equalisation and bias of the HRP901 head. It provides automatic level control (ALC), and operates down to 3 V making it ideal for battery powered applications.
The preamplifier stage has a buffered output, which feeds the BA526 IC by the ROHM Corporation. This IC is a single-channel power amplifier capable of delivering 430 mW into an 8-Ω load when the power supply is 6 V. It has extremely low distortion in the upper band, and soft clipping response, thereby providing a high quality sound. It was a very popular IC and utilised in the WM-1 and WA-55 Walkmans as well. Since it is a mono IC, they use two of them for a stereo application. Unfortunately, a downside of using two of these ICs is the increase in power consumption, and consequently the TCS-310 will provide approximately three hours of operation time on four “AA” sized batteries such as the Sony SUM-3. The same battery compartment also accepts the Sony BP-23 rechargeable battery pack, which helps to save money in the long term. Alternatively, the unit can also accept power from an AC-15A (UK) power adapter.
The sound quality is very good providing you use a good pair of headphones. With a 32-Ω voice coil, you can expect 30 mW output at 10% harmonic distortion, which will knock you back on your ass every time. The circuit design is very confident and sassy, as they do not use a Zobel network, knowing that the performance will be good at any load inductance presented by the headphones. The design shows all the hallmarks of the early Sony engineers, because this is what they did.
The tape speed is smooth due to the metal capstan flywheel; however, the quality resembles the WM-D6C, in this respect. My hearing is extremely sensitive to wow and flutter and when I was a lad, I could detect a 0.1-micron misalignment of the phase coils. :-)
One interesting design feature was the use of a crude servo IC to control the capstan motor speed. Although not a servo in the strictest sense, the circuit is more of a power regulator, and one of the earliest examples of motor power management. We see a greater development in this area on the later designs, where power consumption became more critical.
It is what it is, and it exists today, because if you were looking for a dictation machine, then this would be the high-end, as it records in stereo through a pair of internal microphones. Reliability wise, these machines continue to operate today, even though they are well past their useful life period. With a simple change in drive belt, they continue to provide a high degree of customer satisfaction, which is a testament to good Sony engineering.
Cost / eBay
Before you go running to eBay to see if you can buy one, finish having a look at this multi-page article showing you the inside electronic design and engineering technology utilised in this tape recorder. The price can vary considerably depending upon how complete it is, and whether it is functional. These units are not one of the easiest to repair, and a broken one can take many hours to put right by a competent engineer.
This Article Continues...Sony TCS-310
Sony TCS-310 Repair and Review
Sony TCS-310 inside Look
Sony TCS-310 Changing the Drive Belt
Sony TCS-310 HRP901 Record and Playback Head
Sony TCS-310 Tape Transport Mechanism
Sony TCS-310 PCB and Chipset
Sony TCS-310 Servo Board
Sony TCS-310 Counter
Sony TCS-310 Speaker
Sony TCS-310 Power Supply
Sony TCS-310 Box and Packaging