ONKYO tx-nr646 User Manual

Troubleshooting

Problems may be solved by simply turning the power on/off 

or disconnecting/connecting the power cord, which is easier 

than working on the connection, setting and operating 

procedure. Try the simple measures on both the unit and 

the connected device. If the problem is that the video or 

audio is not output or the HDMI linked operation does not 

work, disconnecting/connecting the HDMI cable may solve 

it. When reconnecting, be careful not to wind the HDMI 

cable since if wound the HDMI cable may not fit well. After 

reconnecting, turn off and on the unit and the connected 

device.

● The AV receiver contains a microPC for signal 

processing and control functions. In very rare situations, 

severe interference, noise from an external source, or 

static electricity may cause it to lockup. In the unlikely 

event that this happens, unplug the power cord from the 

wall outlet, wait at least 5 seconds, and then plug it back 

in.

● Onkyo is not responsible for damages (such as CD 

rental fees) due to unsuccessful recordings caused by 

the unit’s malfunction. Before you record important data, 

make sure that the material will be recorded correctly.

Resetting the unit to the status at the time of shipment 

may solve the problem. If the measures mentioned in the 

troubleshooting do not solve the problem, reset the unit 

with the following procedure. If you reset the unit status, 

your preferences will be reset to the defaults. Note them 

down before starting reset.

¼



1.  While holding down CBL/SAT on the main unit (note 

that step 2 must be performed with this button pressed 

down)

2.  Press  ON/STANDBY on the main unit. "Clear" is 

appeared on the display and the unit will enter standby 

mode.

C l e a r

2

1

¼



1.  While holding down 

1 

RECEIVER on the remote 

controller (note that step 2 must be performed with this 

button pressed down)

2.  Press and hold 

2 

Q for 3 or more seconds until the 

3

 

remote indicator stays lit. Within 30 seconds, press 

1 

RECEIVER again.

1

2

3

¼



● Make sure that the power cord is properly plugged into 

the wall outlet.

● Unplug the power cord from the wall outlet, wait 5 

seconds or more, then plug it in again.

¼



● The AV receiver will automatically enter standby mode 

when Auto Standby or Sleep Timer is set and launched.

● The protection circuit may have been activated. If this is 

the case, when you turn the unit on again, "AMP Diag 

Mode" will appear on the main unit’s display. The unit 

will then enter a mode that detects abnormal conditions. 

If no problems are detected, "AMP Diag Mode" will 

disappear and the unit will return to a normal state. If 

"CHECK SP WIRE" appears on the display, the speaker 

cables may be short-circuited. Turn the unit off, and 

check to see if the cable core of any of the speaker 

cables is in contact with that of another speaker cable or 

with the rear panel. After that, turn the unit on again. If 

"NG" appears, unplug the power cord immediately and 

contact your Onkyo dealer.

WARNING: If smoke, smell or abnormal noise is produced 

by the unit, unplug the power cord from the wall outlet 

immediately and contact the dealer or Onkyo Support.

● Make sure that the speaker setup microphone is not still 

connected.

● Check that the output jack of the connected equipment 

and the input jack of this unit are connected correctly.

● Make sure that none of the connecting cables are bent, 

twisted, or damaged.

● If the MUTING indicator on the display flashes, press 

MUTING on the remote controller to unmute the unit.

● While headphones are connected to the PHONES jack, 

no sound is output from the speakers.

● If "Audio Select" - "PCM Fixed Mode" is set to "On", set 

it to "Off".

If the above does not solve the problem, check the 

following.

¼



● The input selector of this unit needs to be in the position 

that corresponds to the jack where the television is 

connected.

● If your TV does not support ARC, you need, in addition 

to the HDMI OUT MAIN jack connection, a digital optical 

cable connection between the digital audio out optical 

jack of the TV and the DIGITAL IN OPTICAL jack of the 

unit or an analog audio cable connection between the 

audio output jack of the TV and the AUDIO IN TV jack of 

the unit.

¼



● The input selector of this unit needs to be in the 

position that corresponds to the jack where the player is 

connected.

● Check the digital audio output setting on the connected 

component. On some game consoles, such as those