Yamaha FX550 Guitar Effects Processor [Version 1.0], 1992, made in Japan

Link: Owner's Manual [PDF, multilanguage] | elektrotanya [service manual]

Specifications

ELECTRICAL CHARACTERISTICS
Freq. Response: 20 Hz ~ 20 kHz 
Dynamic Range: 85 dB effect OFF
Distortion: Less than 0.1% @ I kHz, effect OFF, max. output

INPUT
Number of Channels: I (mono), Unbalanced
Nominal Level: -20 dB
Impedance: 1 MOhm
Connector: Phone jack (Front, Rear)

OUTPUT
Number of Channels: 2 (stereo out), Unbalanced 
Nominal Level: -20 dB
Impedance: 2kOhm
Connector: Phone jack (Out L, Out R)

HEADPHONE
Number of Channels: 2 (stereo out), Unbalanced 
Nominal Level: -22 dB
Impedance: 150 Ohm
Connector: Stereo phone jack

A/D CONVERTERS
A/D: 16 bit 
D/A: 16 bit
Sampling Frequency: 44.1 kHz

MEMORY
Preset Program: 50 (Prog. No. 1 ~ 50)
User Program: 50 (Prog. No. 51 ~ 99, 00)

EFFECT

Compressor/Limitter, Distortion/Overdrive, 3-Band Parametric Equalizer, Amp Simulator, Stereo Chorus, Stereo Flanger, Symphonic, Auto Pan, Tremolo, Rotary Speaker, Tempo Modulation, Stereo Pitch 1, Stereo Pitch2, Ping-Pong Delay, Stereo Modulation Delay, Reverb, Delay -I- Reverb, Delay —> Reverb, Delay, Tempo Delay

FRONT PANEL
Switch: POWER
Button: COMP, DIST, EQ, MOD, REV, ▲,▼, ◄ , ►, PLAY, EDIT, BYPASS, STORE, UTILITY
Control: INPUT LEVEL
LCD: 15-character x 2-line, Program Number, Bypass
Indicator: PEAK, SIGNAL, COMP, DIST, EQ, MOD, REV, BYPASS, EDIT, UTILITY
Connector: INPUT

REAR PANEL
Control: PHONES LEVEL
Connector: DC 12V IN, TUNER OUT, OUTPUT L (MONO), OUTPUT R, PHONES, MIDI IN, MEMORY INC/DEC (TRIGGER), BYPASS

POWER SUPPLY: DC 12V
DIMENSION (W x H x D ): 220 X 45.2 X 267.5 mm (8.66 x 1.78 x 10.5 ")
WEIGHT: 1.4 kg (3.09 lb)
ACCESSORY: AC Adaptor PA-1207U (U.S & Canadian Models, 120 V AC) / PA-1207H (General Model, 220/240 V AC)

* 0 dB = 0.775 Vr.m.s.