Hitachi SDT-7785 Service Manual

The SDT-7785 was a stereo music centre manufactured by the Hitachi Corporation in 1977. It was an integrated system with amplifier, tuner, tape deck, and turntable. The amplifier power output was 30-watts per channel into 4-Ω loads or 25-watts per channel into 8-Ω loads. The record player section had TP-1000 turntable. It was a 2-speed direct-drive auto-return system with uni-torque dc servo. The stylus was diamond type DS-ST 104. You can find more information regarding its specifications in the following sections of this multi-page article.

Review

This was a wonderful bit of electronic engineering with 15 ICs and 54 transistors that is still highly useful. Providing you find a system that is in good working condition, it is a joy to use and sounds good as well. In this design, the power amplifier section is based on the Hybrid IMST modules, which I particularly like the sound of. It has a pair (one for each channel) of STK-080 modules manufactured by the Sanyo Corporation. These can damage easily if the speaker terminals are shorted, hence be very careful as replacement modules are expensive and difficult to find.

Specifications

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