TX-NR676 problems almost always fall into three buckets: it blinks and shuts off (protection mode), it shows "NG" during speaker setup, or it drops HDMI video — and that last one matters, because the TX-NR676 is one of the Onkyo models with a known HDMI-board weakness. Figure out which bucket you're in, then fix accordingly.
It blinks and shuts off (protection mode)
The receiver sensed a fault on the amp output. Almost always a speaker-wire short (a stray strand bridging the terminals), sometimes overheating.
- Unplug and check every speaker terminal for stray strands; re-strip and re-seat.
- Test with all speakers disconnected — if it stays on, reconnect one at a time to find the bad cable. If it trips bare, it's internal.
- If it only trips when hot, improve ventilation and dust the vents; let it fully cool.
- Clear a latch: power-cycle (unplug at least 30 seconds), then a microprocessor reset per the manual.
"NG" during speaker setup
During AccuEQ, "NG" for a channel means the receiver couldn't detect that speaker. Re-seat the speaker wires (+/− correct, no shorts), plug the setup mic fully in at ear height pointing up, run it in a quiet room, and confirm the speaker actually plays. If you're seeing an NG L/R AccuEQ result specifically, that has its own narrower set of causes.
No HDMI video / "No Signal" — and the board issue
First rule out the easy stuff: confirm the input assignment, reseat and swap the HDMI cable for a certified one, set the power-on order (source → receiver → TV), and update the firmware. The full Onkyo HDMI no-signal walkthrough covers each of these in order. Connect the source straight to the TV to confirm the source and cable are fine.
But if HDMI inputs progressively die — one port stops passing video, then more, or it loses video while audio still works — that's the TX-NR676's known HDMI-board fault, not your cable or settings. No reset fixes a failed HDMI board; it's a board-level repair (or a workaround: use the receiver for audio and run video from the source directly to the TV, returning audio over ARC). If you're past warranty and the board's gone, weigh the repair against replacement.
FAQ
My TX-NR676 blinks red and shuts off. Protection mode, usually a speaker-wire short. Disconnect all speakers and power on; if it stays on, reconnect one at a time to find the short.
HDMI video died but audio still works. That's the classic TX-NR676 HDMI-board symptom. Rule out the cable first, but a progressive HDMI failure is a board fault — run video direct to the TV and audio over ARC as a workaround.
What does NG mean during setup? The receiver couldn't detect that speaker through the mic — re-seat the wires and check the mic placement.
Should I repair it? If it's a failed HDMI board out of warranty, weigh the board repair cost against a newer receiver. The audio amp is often still fine, so the direct-to-TV workaround can keep it useful meanwhile.
For codes not covered here, the Onkyo receiver error code list maps the rest to their causes.