Denon DRA 685

Hello. My name is Dave. Does this unit have a tape monitor button? If it does, you probably have it switched on. Make sure you turn down your volume before turning the tape monitor off. If not a tape monitor, it may may another switched path that you have engaged. Same fix as above.

Hello. DC Protection is not something you can turn off. It is a protection system engaged by one of the microprocessors (computers) within your receiver. If any of the amplifiers are bad, and producing DC voltage at the output, the micro will immediately turn the unit off, to lesson further damage to the amplifier or speaker system. There can be other causes of why the unit's DC Protection relay is not engaging, but 90% of the issues, are related to amplifier damage.

Dave

Generally speaking, an amp protects itself from heat, shorts and overloads by refusing to turn on or stay on.

Overloads can be from excessive periods of high output or marginally low impedance loading by the speakers; and shorts would be wiring issues or a speaker blowing up.

You should be able to feel if it's hot. WHY is it overheating? Make sure it has sufficient ventilation on all sides and that vent holes are not blocked by dust balls. Ensure the fan (if equipped) is running as designed (some only operate on demand). Clean dust and debris from it.

If the amp comes back on after cooling, you're lucky. They only have so many self-protection cycles in their lives so continuously resetting or cycling their power without addressing the cause can do more harm than good.

If it protects immediately on a cool power up you should disconnect the speaker connections and try it 'naked'. If it comes up then diagnose which lead(s) are shorted. If it does not come up the problem is internal and should be left to an experienced and competent hands-on tech.

I just recently picked up a Denon DRA-685 receiver that was stuck in protection mode. I found a site online that suggested it was due to two bad resistors on the main circuit board. More specifically resistor R-105 and R-106. They are both 1 ohm x 1 watt resistors. I ordered these from a supplier on Amazon for a few dollars, and just snipped the old resistors off, leaving the soldered leads sticking out. I then thinned the new leads and soldered them to the protruding wires, so I didn't have to remove everything. The unit now works like new. I'm happy I spent the time doing this, and grateful to the tech who discovered the common problem with this unit. Hope this can help somebody else. H

Good start checking your speaker wires. A better test would be to disconnect them entirely in case there's a short inside the speaker itself. Keep the volume WAY down when you power back up and see if it runs for a while. If it does, then you do have a short somewhere - probably inside speaker. If it trips off, you might want to think in terms of getting the problem fixed rather than defeating the protection circuit.

The reciever will go into protection mode when there is a short in the speaker wires or the amplifier was overloaded. What I would do first is verify that none of the speaker wire connections are loose at the back of the reciever or at each speaker. And verify that none of the wires are making contact with each other. Then label each speaker wire as you remove them from the reciever so you can re-install them correctly. After you have disconnected the speaker wires try unplugging the reciever for 10 to 15 minutes. Most recievers have a self-resetting overload protection switch and this should reset it back to normal. Now try plugging the reciever back in and turn it on without the speaker wires connected. It should be out of protection mode now. If it is still in protection mode verify that there is not a reset switch somewhere on the back of the reciever. If it is not in protection mode now then proceed to connect one speaker set at a time and turn on the reciever to see if it goes into protection mode. If it goes into that mode after connecting a speaker then that speaker is the cause of the problem. If it does not go into the mode after all speakers are connected then try turning the volume up. If it goes into protection mode then there could be an internal short on the amplifier or a incorrect OHM rated speakers connected to reciever. Verify that the speakers are rated the correct OHMS.

you can use a 1/8 inch female to stereo RCA adapter and plug the patch cable into one of your inputs like DVD or CD player. The signal to noise ratio on those inputs is pretty good.

You may have a speaker that is damaged and causing the protection to operate. Try unhooking all the speaker wiring from the receiver, turn the volume to minimum, and see if the protection still comes on. If the receiver is okay, you can start checking the speakers and wires to determine which one(s) may be responsible.

If the unit continues to go into protection even with no speakers connected, the trouble is inside the receiver. No protection circuit is absolutely perfect, so it's possible something failed before the circuit kicked in. Without the proper test equipment and service information, you won't be able to try fixing this yourself. Take the unit to a shop for an estimate.

Thanks for using Fixya! Hope your receiver's back in service soon.

Hi....you may want to check the speaker fuse, located on the rear of the unit.. sometimes too small wattage speakers get hooked up and the speaker fuse will blow as to not hurt the speakers.
Hope this helps.
Squipps

your loudspeakers tweeters have shortcut *try them separetly)