PROTECT on a Sony STR-DH790 means the receiver’s protection circuit has tripped, and it will shut itself off within a few seconds. To fix it, unplug the receiver for 30 minutes, disconnect every speaker and the subwoofer, then reconnect them one at a time until you find the one that sets it off.
The usual causes are a speaker wire short, overheating, speakers with too low an impedance, or a power surge or outage. Each one can be checked at home with no tools beyond your hands and a flashlight. A factory reset won’t clear PROTECT, because the problem is electrical, not a setting. If PROTECT still appears with no speakers connected at all, the receiver probably needs service.
What’s likely causing it
Use the clues below to decide where to look first. The step-by-step check further down will find the cause either way.
| Cause | Common clue |
|---|---|
| Speaker wire short | PROTECT shows right after you moved, added, or rewired a speaker. A stray copper strand touching the next terminal is enough. |
| Overheating | PROTECT shows after a long movie or loud session, or the receiver sits in a closed cabinet. |
| Impedance too low | PROTECT shows at higher volume. The STR-DH790 is made for speakers rated 6 to 16 ohms. Some home speakers are rated 4 ohms, which is below that range. |
| Power surge or outage | PROTECT started after a storm, a tripped breaker, or a power flicker. |
| Internal fault | PROTECT shows even with every speaker disconnected. |
Is it really PROTECT?
The STR-DH790 can also turn itself off for normal reasons. If you didn’t see the word PROTECT on the display, check these first.
- Auto standby. Press AMP MENU, go to <SYSTEM> > AUTO.STBY, and set it to STBY OFF if you don’t want the receiver switching off on its own when it’s idle.
- Sleep timer. If the SLEEP indicator is lit on the display, a timer is set.
- USB FAIL. This is a different message. It means too much current was drawn from the POWER SUPPLY (USB) port on the back. Turn the receiver off, unplug the USB device, and turn it back on.
How to fix PROTECT on the STR-DH790, step by step
This follows Sony’s own order for the STR-DH790. Don’t skip the waiting periods. The first gives the protection circuit time to reset. The second makes sure the receiver is fully warmed up, since some faults only show when it’s hot.
Warning: Always unplug the power cord before you touch speaker wires. Sony warns that bare wires touching each other at the terminals can damage the amplifier.
- Unplug the receiver’s power cord from the wall.
- Wait 30 minutes. Sony recommends this full wait whenever PROTECT may have come from a surge or power failure.
- While you wait, disconnect every speaker wire and the subwoofer cable from the back of the receiver.
- Make sure nothing covers the receiver or blocks its ventilation holes. Move it out of a closed cabinet if it’s in one.
- Check each speaker’s impedance rating, usually printed on a label on the back of the speaker. Every speaker should fall within the range printed on the receiver’s rear panel, which is 6 to 16 ohms.
- Plug the receiver in and turn it on with no speakers connected. If PROTECT appears now, stop here. The fault is inside the receiver, and it needs service.
- If the receiver stays on, turn it off and unplug it again.
- Reconnect only the front left and right speakers. Check that each wire end is tightly twisted and that no strand touches another terminal.
- Plug in the receiver, turn it on, and play something at a normal to fairly loud volume for at least 30 minutes so it fully warms up.
- If there’s still no PROTECT, turn off and unplug the receiver, then add one more speaker. Turn it on and test again.
- Keep adding one speaker at a time, unplugging the receiver before each connection. When PROTECT returns, the speaker you just added, or its wire, is the problem.
Wiring mistakes that are easy to make on the STR-DH790
The STR-DH790 is a 7.2-channel receiver, and one set of its terminals does four different jobs. That makes a few mistakes more likely than on a simpler receiver.
Loose strands at the terminals
Sony says to strip about 10 mm (13/32 in) of insulation and twist the strands tight. Stripping too much leaves bare wire that can touch the next terminal or the metal back panel. Trim any long or splayed ends and re-twist them.
The shared SURROUND BACK/HEIGHT terminals
The terminals labeled SPEAKERS SURROUND BACK/HEIGHT (FRONT B/BI-AMP) can power surround back speakers, height speakers, a second pair of front speakers, or one half of a bi-amp connection for your front speakers. They are only a pair, so only one of those uses at a time. If you have a single surround back speaker, Sony says to connect it to the L terminals.
Bi-amping with the metal jumpers still on
If you bi-amp speakers that have two sets of terminals, Sony says to remove the Hi/Lo metal fittings (the jumper plates or bars between the terminal pairs) from the speakers first. Leaving them on joins two amplifier channels together, and Sony warns it can make the receiver malfunction.
4-ohm speakers
A speaker rated below 6 ohms asks the amplifier for more current than it’s built to supply, especially at high volume. Sony’s general advice for low-impedance speakers is to keep the volume lower and to set individual speaker levels to 0.0 dB or below. The better fix is speakers rated 6 ohms or higher.
PROTECT after a power outage
A surge or outage can trip the protection circuit even when your speakers are fine. Before you pull any wires, try this first:
- Unplug the receiver from the wall.
- Wait a full 30 minutes.
- Plug it back in and turn it on.
If PROTECT is gone, you’re done. If it comes back, work through the full step-by-step check above. As a general precaution, a surge protector can help guard against future spikes.
Why a factory reset won’t fix PROTECT
A factory reset clears settings like the speaker pattern and calibration. PROTECT is triggered by current, heat, or voltage, not by a setting, so a reset leaves the cause in place. It also erases your whole setup. See our STR-DH790 factory reset guide for when a reset does make sense.
After you’ve found the problem
- Replace a damaged or frayed wire rather than taping it.
- If you changed which speakers are connected, rerun Easy Setup so the receiver knows about them. If you use the SURROUND BACK/HEIGHT terminals for height speakers, our STR-DH790 Atmos speaker setup shows the right terminal assignment.
- Run Auto Calibration again after any wiring change. Our guide to running D.C.A.C. on the STR-DH790 walks through it.
- Leave space around the receiver. Sony notes the cabinet gets hot during use and needs airflow.
When to contact Sony
Get the receiver serviced if PROTECT appears with no speakers connected, or if it keeps coming back after you’ve checked the wires, vents, and impedance. Sony notes that protection mode exists to prevent permanent damage, so repeatedly forcing the receiver back on isn’t a fix. Sony’s PROTECT page in the STR-DH790 Help Guide and its support article on PROTECT errors list the same checks, plus how to reach support.