Description
OTTO SANYO DCA-V3 Stereo Integrated Amplifier Rare Vintage Audio 1978 Maintained Domo Arigato! Welcome, Thank you for your visit. Description Operation confirmed. The appearance has small scratches, tarnish, dirt, etc. due to normal use. For other appearances, please refer to the photo. *The power supply voltage is AC 100V specification in Japan. Please be careful about the voltage in your country.If the power supply voltage is different, you will need a voltage transformer. *There is no original box. Overview The H-R IC pulse power supply is used in the power supply section.In this power supply, the AC power supply is rectified directly to DC, converted to ultra-high frequency pulses of 35 kHz, and then stepped down and rectified by a high-frequency ferrite core transformer to obtain the desired DC voltage.Feedback is applied from the DC output terminal of the power supply, and an error amplifier circuit catches voltage fluctuations at the output terminal and transmits the signal to a pulse width modulator using a photocoupler. The pulse width modulator controls the pulse width modulation (PWM) of the switching transistor, and the pulse width is narrowed when the DC output voltage rises above 40 V and widened when it falls below 40 V to achieve constant voltage.In a pulsed power supply, the detection of voltage fluctuations is located at the output end of the power supply hunting tail after the DC rectification and smoothing circuits have passed through, so that the entire power supply circuit is included in the feedback loop for stabilization, resulting in very low voltage fluctuations. For example, the input voltage (operating voltage) tolerance is very wide, from 85 V to 135 V, and at the same time, the load voltage fluctuation rate is kept within 2% for 0 to 2.3 A.The DCA-V3 has a very high switching frequency of 35 kHz compared to conventional pulse power supplies, which have a switching frequency of about 20 kHz. This was achieved by developing a hybrid IC capable of high-speed switching with high withstand voltage, which significantly reduces the number of components and improves reliability.Pulse power supplies handle high frequencies, and if they leak outside, the amplifiers are greatly affected. To prevent this, the entire unit is CAN shielded to reduce unwanted radiation. The circuit configuration of the power amplifier section consists of a FET source follower differential input, second-stage emitter follower differential amplification, and a low-distortion power IC.The power IC is a Darlington-connected 2-stage pure complementary, DC amplifier configuration. The transistors used in each stage are carefully selected low-noise high-ft transistors. The tone control circuit uses a BAX type.The circuit configuration consists of an emitter follower input and a tone control IC. When the tone control is not used, the tone element is disconnected from the tone circuit by turning the Tone SW off, resulting in a pure flat amplifier. The equalizer circuit consists of three stages: a differential input current mirror circuit with super low-noise FETs, a second stage emitter grounded amplification, and a final stage pure complementary SEPP-OCL.The FET used in the first stage is of extremely low noise specification, and the characteristics of the two FETs are matched both electrically and thermally, resulting in a better signal-to-noise ratio when mounted on the cartridge than those using transistors as the first stage elements. MC head amp is equipped.The circuit configuration uses a parallel complementary circuit with low-noise dual transistors, and four transistors are used per channel. A fast-response protection circuit is provided.The fast-response design operates quickly when the temperature of the power IC rises above 85°C or when harmful DC components are generated in the speaker. A low filter and subsonic filter are provided. A tape monitor switch and duplicate switch are provided. Gold-plated terminals are used for the Phono terminals. Specifications
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