An Onkyo TX-SR393 or TX-SR494 that won't power on — dead, or clicking off the moment it tries to start, or sitting with a blinking standby light — is usually in protection mode or stuck in a power state, not a dead unit. The fixes are the same for both models, and a proper power-drain clears a lot of them.
Start with a power-drain
- Unplug it from the wall (the actual cord, not just standby).
- Hold the receiver's power button for 30 seconds while unplugged, to drain residual charge.
- Plug it into a different outlet (skip the power strip for the test) and try again. This clears a stuck microprocessor/power state and fixes many "won't turn on" cases on its own.
If the standby light blinks or it shuts off when starting
That's protection mode — it sensed a fault on the speaker output, the same trigger behind many Onkyo receiver error codes. Almost always a speaker-wire short:
- Unplug and check every speaker terminal for stray strands bridging the posts; re-strip and re-seat each wire.
- Disconnect all speakers and power on. If it powers up and stays on with nothing connected, the fault is a speaker cable or speaker — reconnect them one at a time to find it. If it still won't start bare, the fault is internal.
- Check impedance — speakers below 6Ω (or two on one channel) can trip protection on these budget amps.
If it's completely dead
- Confirm the outlet works and the power cord is fully seated at the receiver end. Try a known-good outlet.
- Microprocessor reset per the manual (commonly holding a front button while powering on) after the power-drain.
If it stays completely dead after a known-good outlet, a power-drain, and a reset — no lights, no click — the power supply has likely failed. On a budget receiver that's a repair-vs-replace decision, but only after the free steps above, because they genuinely revive a fair number of these.
FAQ
My Onkyo TX-SR494 won't turn on at all. Do the power-drain first: unplug, hold the power button 30 seconds, plug into a known-good outlet. That clears a stuck power state in many cases.
The standby light blinks and it won't start. That's protection mode — usually a speaker-wire short. Disconnect all speakers and power on; if it starts, reconnect one at a time to find the short.
It clicks on then immediately off. Same protection trigger, most often a short or a low-impedance load. Check the speaker wiring and impedance.
Nothing works after all that. A failed power supply is likely on a completely dead unit. Weigh the repair against a new receiver, since these are budget models.
Once it powers back up, if TV sound still won't pass through, see the TX-SR494 ARC fix.