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Sansui TU-666 tuner
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General:
Nice tuner with good performance, made by Sansui in 1970.
Specifications:
Sansui TU-666
Type: Mono/Stereo Tuner
Tuning Bands: FM, MW
Tuning Scale: Round Analogue
FM Tuning Range: 88 to 108 MHz
MW Tuning Range: 535 to 1605 kHz
Sensitivity: 2.0µV (FM), 20µV (MW)
Signal to Noise Ratio: 65dB (FM)
Distortion: 0.8% (FM)
Selectivity: 55dB (FM), 20dB (MW)
Output: 770mV
Semiconductors: transistor: 24, FET:1, IC:1, Diode: 19
Dimensions: 335x 127 x 276mm
Weight: 4,8kg
Year: 1969/1970

Round scale ^
Special futures:
FM/AM round scale with tuning meter and stereo lamp, one colour: green.
Click here to download the TU-666 / AU-666 brochure in PDF format

User Manual:
Click here to download the TU-666 usermanual in PDF format (construction)

TU-666 with AU666 ^
Schematic:
Click here to download the TU-666 schematic in PDF format
Click here to download the TU-666 stereo decoder schematic in PDF format
There are transistors and one FET used and a lot of diodes: only 1 early IC.
   

Internal Sansui TU-666 ^
Modifications:
The build quality is excellent, although some 
parts are not easely accessable, 
like the FM front-end that is bigger than in the TU-555. 
The FM front-end suffers in many TU-666 instability caused by bad soldering by 
Alps, 
together with the instability of the power supply the tuner has sometimes problems with 
stable tuning 
and tends to walk away from the tuned station, the S-meter is of average quality.
All electrolytic caps are out of specs after 50 years. Wiring is is much better and cleaner 
than the TU-555, 
but still some wires are too long, a problem that 
many Sansui gear have from that time frame. 
You may exchange all electrolytic 
capacitors. You may add a resistor of  1 Ohms 
@ 5 Watts in series with the bulbs of the 
scale, 
It lowers the heat dissipation of the bulbs and makes the light in the scale 
somewhat softer.
 

Bottom view ^

FM - IF section ^
AM section V

Audio Section & stereo-decoder ^

Power supply pcb ^

3 gang FM capacitor ^

Power supply Transformer ^

Back ^

Wood top ^

Sound:
The FM reception and sound of this tuner is very good, regarding the some 50 years of age: A real high-end product of its time.

TU-666 & AU-666 ^
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© PE1MMK Hans Hilberink, last update: 15-09-2019.