Sony st-s333esa (1991-1992)

Name: Sony st-s333esa
Brand: Sony

A high-end FM/AM tuner from Sony's 333 series, released in 1991 with precision circuitry and MUSE-grade components.

Overview

The Sony ST-S333ESA is a stereo FM/AM tuner released in 1991 as part of Sony's premium 333 series. It follows the ST-S333ESG and comes before the ST-S333ESJ. It was marketed from 1991 to 1992 and sold in Japan for ¥55,000. It was built for audiophiles. It has a station name display and multi-process memory for storing tuning settings. The microcomputer stops during reception to reduce noise and preserve sound quality. Two color variations exist: gold and black.

Specifications

Receiving frequency band (FM)	76.0 mhz to 90.0 mhz
Practical sensitivity (FM)	10.3 dBi (1.8 µV/75 ohms)
FM 50 dB quieting sensitivity	Mono: 14.8 dBi (3.0 µV/75 ohms); Stereo: 37.3 dBi (13.0 µV/75 ohms)
Frequency characteristic/response (FM)	30 Hz - 15 kHz (+0.2, -0.8 dB)
Signal-to-noise ratio (FM)	Mono: 84 dB; Stereo: 80 dB
Effective selectivity (FM)	80 dB
Total harmonic distortion rate (FM, wide, 1 kHz)	Mono: 0.08 %; Stereo: 0.1 %
Image interference ratio (FM)	100dB
Stereo separation (FM)	45 dB at 1 kHz
FM capture ratio	1.0 dB
Antenna terminal (FM)	2 x 75 Ω unbalanced type
Receiving frequency band (AM)	531 kHz to 1602 kHz
Sensitivity (AM)	300 µV/m
Signal-to-noise ratio (AM)	50 dB
Total harmonic distortion rate (AM, 400 Hz)	0.8 %
Selectivity (AM, 9 kHz)	wide:50dB narrow:65dB
Antenna terminal (AM)	External antenna terminal
Power	AC 120 V, 60 Hz
Power consumption	15 W
External dimensions	430 x 105 x 328 mm
Side Wood Removal	Width 430 mm
Weight	6.0 kg
Attachment	Wireless Remote Control RM-J300

Design

The ST-S333ESA uses a radial power supply layout. It connects the power and signal paths to the front-end, IF, DET, MPX, and AM circuits over minimal distance, and it uses single-point grounding to reduce noise. The MPX stage has a newly developed GIC filter. Earlier models could switch it off, but here it stays on permanently. Nichicon MUSE green capacitors are used, particularly in the power supply section, which includes 2200μF 63V 85℃ negative black and 1000μF 63V 85℃ MUSE capacitors. Key ICs are the Sony CXA1064 (MPX), Sanyo LA1235 (IF), Sanyo LA1245 (AM), and Sony D75108CW (control microcomputer). The D75108CW runs different ROM firmware (C79) than the ST-S333ESG (A76). The front-end has RF coils L101 - L104 and a grounded shield plate. The mixer uses a 3SK122 FET and the PLL section uses the CX-7925B. Adjustment parts include several trimmer capacitors (CT101 - CT103, CT271), potentiometers (RV201 - RV402), and IFT units. The circuit board layout is identical to the ST-S333ESG, but the ESA adds a muting circuit diode and omits the MPX filter relay. Fujitsu relays handle antenna and IF band switching.

Context

The ST-S333ESA was part of Sony's 333 series (333シリーズ), a line of high-end tuners that began with the ST-S333ESXⅡ, then the ST-S333ESG, then the ST-S333ESA, and finally the ST-S333ESJ. One original owner bought it new at launch. It was meant to be stacked on top of an amplifier, which likely caused significant heat buildup. In listening tests, some users heard no clear sonic difference between the ESA and the earlier ESG. Others noted subtle changes, possibly due to the MUSE capacitors. After a full capacitor replacement, one owner reported a dramatic improvement in sound.

Market

Common problems start with drift in the fuse resistors (R119, R203, R207, R211, R227, R259, R274, R279, R292, R301, R327, R403, R410, R511, R516, R626, R910, R921, R931, R-JW) from heat exposure, often from poor ventilation or stacking. The memory backup capacitor C605 (0.1F/5.5V) frequently fails, and station presets erase overnight. Trimmer capacitor CT271 can develop noise. Solder cracks are common at the ground bars, audio terminals, and antenna connectors. RF coil cores like L102 may crack, and adjustment cores (e.g., in IFT101) can get stuck if over-tightened. Many units show signs of prior improper adjustment, with potentiometers turned fully. The repair is to replace the fuse resistors (some need a 1W rating), upgrade C605 to a 1F/5.5V capacitor, replace C604 with a 10uF/50v electrolytic, and re-solder the cracked joints. Faulty IFT units can be replaced with donor parts from earlier 333-series models.