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Onkyo A 9555 - Service Manual

Onkyo A 9555
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A-9555
SERVICE MANUAL
SERVICE MANUAL
INTEGRATED AMPLIFIER
Black, Silver and Golden models
MODEL A-9555
Ref. No. 3920
122005
G UGT, G MGT
G UDT, G MDT
G UGR, G MGR
220-230V AC, 50/60Hz
120V AC, 60Hz
220-230V AC, 50/60Hz
120V AC, 60Hz
230-240V AC, 50Hz
B UDC, B MDC
B UPP, B MPP
120V AC, 60Hz
230-240V AC, 50Hz
S UDC, S MDC
S UPP, S MPP
RC-627S
RC-627S
SAFETY-RELATED COMPONENT
WARNING!!
COMPONENTS IDENTIFIED BY MARK ON THE
SCHEMATIC DIAGRAM AND IN THE PARTS LIST ARE
CRITICAL FOR RISK OF FIRE AND ELECTRIC SHOCK.
REPLACE THESE COMPONENTS WITH ONKYO
PARTS WHOSE PART NUMBERS APPEAR AS SHOWN
IN THIS MANUAL.
MAKE LEAKAGE-CURRENT OR RESISTANCE
MEASUREMENTS TO DETERMINE THAT EXPOSED
PARTS ARE ACCEPTABLY INSULATED FROM THE
SUPPLY CIRCUIT BEFORE RETURNING THE
APPLIANCE TO THE CUSTOMER.
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TEL 13942296513 QQ 376315150 892498299
TEL 13942296513 QQ 376315150 892498299
http://www.xiaoyu163.com
http://www.xiaoyu163.com

Table of Contents

Other manuals for Onkyo A 9555

Preview: Instruction Manual
Instruction Manual20 pages

Questions and Answers

  • J
    james31Aug 18, 2025
    Why doesn't the remote controller work for my Onkyo A 9555 Amplifier?
    • B
      Bethany FernandezAug 18, 2025
      If your Onkyo Amplifier remote controller isn't working: * Ensure the batteries are installed with the correct polarity. * Install new batteries, avoiding mixing different types or old and new ones. * Make sure the remote isn't too far from the A-9755/A-9555 and there are no obstructions between them. * Ensure the A-9755/A-9555 isn't exposed to direct sunlight or inverter-type fluorescent lights; relocate if needed. * If the A-9755/A-9555 is in a rack or cabinet with colored glass doors, the remote may not work reliably when the doors are closed.
  • B
    Bradley WallaceAug 21, 2025
    How to eliminate noise from my Onkyo A 9555?
    • B
      bonniehopkinsAug 21, 2025
      If you are hearing noise from your Onkyo Amplifier, avoid bundling audio cables with power cords or speaker cables, as this can degrade audio performance. Also, an audio cable may be picking up interference, so try repositioning your cables.
  • K
    Keith HaleAug 25, 2025
    Why does the volume control have no effect on my Onkyo Amplifier?
    • Z
      zbowenAug 25, 2025
      When using the A-9755 as a power amplifier (MAIN IN function), the Volume control has no effect. Adjust the volume on the connected preamp instead.
  • T
    Tiffany YoungAug 27, 2025
    Why doesn't the muting function work on my Onkyo A 9555?
    • K
      Kimberly ThompsonAug 27, 2025
      When using the A-9755 as a power amplifier (MAIN IN function), the Muting function does not work. Use the muting function on the connected preamp instead.
  • P
    pachecoscottAug 30, 2025
    What to do if the STANDBY indicator is flashing on my Onkyo A 9555 Amplifier?
    • A
      Adam BondAug 30, 2025
      If the STANDBY indicator on your Onkyo amplifier is flashing, the amp protection circuit has been activated. Immediately remove the power cord from the wall outlet and contact your Onkyo dealer.
  • T
    Timothy GouldSep 2, 2025
    What to do if my Onkyo Amplifier A-9755/A-9555 locks up?
    • L
      Lauren HansonSep 2, 2025
      If your Onkyo Amplifier A-9755/A-9555 locks up due to interference, unplug the power cord from the wall outlet, wait at least ten seconds, and then plug it back in again.
  • L
    Logan HenrySep 5, 2025
    Why do the tone controls have no effect on my Onkyo Amplifier?
    • K
      Kayla MorenoSep 5, 2025
      If the tone controls on your Onkyo Amplifier have no effect, the PURE DIRECT function may be enabled. If the PURE DIRECT indicator is lit, press the [PURE DIRECT] button to turn the function off.
  • N
    Nicholas HardinSep 8, 2025
    Why can't I control other components with my Onkyo Amplifier?
    • E
      Elizabeth SmithSep 8, 2025
      If you can't control other components with your Onkyo amplifier, and if it’s an Onkyo component, ensure that both the cable and analog audio cable are properly connected. A connection using only an cable will not work.
  • D
    Diana PetersonSep 12, 2025
    Why can't I record with my Onkyo A-9755 Amplifier?
    • C
      Charles WoodSep 12, 2025
      If you cannot record with your Onkyo A-9755 amplifier: * The component connected to the MAIN IN jacks cannot be recorded. * When using the A-9755 as a power amplifier (MAIN IN function), recording is not possible.
  • D
    Daniel RiversNov 14, 2025
    Why is there no sound coming from my Onkyo Amplifier, or why is it very quiet?
    • J
      Jennifer AyersNov 14, 2025
      If your Onkyo Amplifier is not producing sound or the sound is very quiet: * If the A-9755 is used as a power amplifier (MAIN IN indicator lights up), the sound from components connected to the preamp is output. To output the sound from a component that’s connected to the A-9755, or to use the A-9755 as a preamp, press the [POWER AMP DIRECT (MAIN IN)] button for 3 seconds until the MAIN IN indicator goes off. * Ensure all audio plugs are fully inserted. * Verify that all components are connected properly. * Check the speaker cable polarity and ensure bare wires contact the metal part of each terminal. * Select the correct input source. * If the Volume indicator flashes slowly, press the remote's [MUTING] button to unmute the A-9755/A-9555. * Check cables for bends, twists, o...

Summary

Safety Warnings and Precautions

Critical Component Identification

Components marked are critical for fire/shock risk. Replace with specified ONKYO parts.

Insulation Measurement Before Return

Measure leakage-current or resistance to ensure insulation before returning to customer.

Service Procedures

Fuse Replacement Guidelines

Instructions for replacing fuses with correct type and rating to prevent fire hazard.

Unit Initialization and Pre-shipment Settings

Schematic Diagrams: Power Amplifier

Left Channel Amplifier Circuit

Detailed schematic for the left channel amplifier.

Right Channel Amplifier Circuit

Detailed schematic for the right channel amplifier.

Schematic Diagrams: Pre-Amplifier

Input Selector and Tone Control Circuits

Schematics for input selection and tone control sections.

Schematic Diagrams: Microprocessor

Microprocessor and Control Board Schematics

Detailed schematic of the microprocessor and control boards.

Schematic Diagrams: Phono Equalizer

Phono Equalizer Preamplifier Circuit

Detailed schematic of the phono equalizer stage.

Schematic Diagrams: Power Supply

Power Supply PC Board and AC Input

Schematic of the power supply board and AC input connections.

Onkyo A 9555 Specifications

A-9755

Power Output IconPower Output
power output (8 Ω, 1 kHz, DIN)150 W + 150 W
power output (4 Ω, 1 kHz, JEITA)300 W + 300 W
dynamic power (3 Ω, Front)330 W + 330 W
dynamic power (4 Ω, Front)270 W + 270 W
dynamic power (8 Ω, Front)170 W + 170 W
Audio Performance IconAudio Performance
total harmonic distortion (THD)0.08 % (1 kHz, 1 W)
damping factor25 (Front, 1 kHz, 8 Ω)
input sensitivity and impedance (CD)200 mV, 50 kΩ
input sensitivity and impedance (PHONO MM)2.5 mV, 50 kΩ
output level and impedance (REC OUT)200 mV, 2.2 kΩ
Frequency and Tone Control IconFrequency and Tone Control
frequency response (CD)10 Hz–60 kHz, +1 dB–3 dB
tone control (BASS)+10 dB, –10 dB, 100 Hz
tone control (TREBLE)+10 dB, –10 dB, 20 kHz
loudness control (50 Hz)+10 dB
loudness control (10 kHz)+2 dB
Power IconPower
power supplyAC 230-240 V, 50 Hz / AC 220-230 V, 50/60 Hz
power consumption125 W
stand-by power consumption0.3 W
Weight and Dimensions IconWeight and Dimensions
dimensions (W × H × D)435 × 144 × 431 mm
weight17.6 kg
speaker impedance4–16 Ω

A-9555

Power Output IconPower Output
power output (8 Ω, 1 kHz, DIN)100 W + 100 W
power output (4 Ω, 1 kHz, JEITA)200 W + 200 W
dynamic power (3 Ω, Front)230 W + 230 W
dynamic power (4 Ω, Front)200 W + 200 W
dynamic power (8 Ω, Front)120 W + 120 W
Audio Performance IconAudio Performance
total harmonic distortion (THD)0.08 % (1 kHz, 1 W)
damping factor25 (Front, 1 kHz, 8 Ω)
input sensitivity and impedance (CD)200 mV, 50 kΩ
input sensitivity and impedance (PHONO MM)2.5 mV, 50 kΩ
output level and impedance (REC OUT)200 mV, 2.2 kΩ
Frequency and Tone Control IconFrequency and Tone Control
frequency response (CD)10 Hz–60 kHz, +1 dB–3 dB
tone control (BASS)+10 dB, –10 dB, 100 Hz
tone control (TREBLE)+10 dB, –10 dB, 20 kHz
loudness control (50 Hz)+10 dB
loudness control (10 kHz)+2 dB
Power IconPower
power supplyAC 230-240 V, 50 Hz / AC 220-230 V, 50/60 Hz / AC 120 V, 60 Hz
power consumption120 W
stand-by power consumption0.3 W
Weight and Dimensions IconWeight and Dimensions
dimensions (W × H × D)435 × 148 × 431 mm
weight13.0 kg
speaker impedance4–16 Ω
View in Manual

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