CurtPalme.com Home Theater Forum

drice1234 · Joined: 07 Oct 2006 Posts: 1309 Location: Allen, Texas

OK, this is a long shot but I thought I would try to see if you component level guys might have an idea. I purchased a broken Denon AVR-688 receiver. The description of the problem was "no audio output" I hooked up the front left and right speakers and ran through the tone test and it sounded alright. I hooked a source into the various inputs and found the following on all of the inputs. When the volume is turned all of the way down it is at -80db, once I get to around -40db I start to hear the audio. Any thoughts of where to begin looking for the problem?
Thanks
Dan

**Curt Palme** · Posted: Mon May 25, 2009 2:49 pm Post subject:

I have no idea what you're asking? You hear audio you say. Sounds like everything is working fine. Can you rephrase the question?

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

I think what he is saying Curt is, when he use the internal test sound the audio is fine. Or at least for the 2 fronts. So that would eliminate the output section. Then when he inputs something he barely gets any sound out. This is on all inputs. So this would eliminate the input and switching section. So that leaves the processing section. Or a power loss to a circuit that requires power to function.

Options:
1: Did you try different sources?
2: Remove cover and unplug and reattach any wire harnesses you find. It could be a bad connection.
3: Check all screws holding boards in for looseness. Ground screws cause great havoc in audio devices.
4: Acquire a service manual to trace circuit.

**Curt Palme** · Posted: Mon May 25, 2009 3:14 pm Post subject:

OK, your interpretation is better than mine. He didn't say he didn't get audio, he said it started at -40, which is about right. Smile

Input/output pre/power amp loop connectors missing?

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

**Curt Palme** · Posted: Mon May 25, 2009 3:26 pm Post subject:

True. 0 cups so far. Very Happy

drice1234 · Joined: 07 Oct 2006 Posts: 1309 Location: Allen, Texas

Mac you interpreted correctly. Sorry for not being more clear. I will try the checking for loose connections and tighten screws but a schematic would be of no use for my abilities. If the above does not work I may see if you want the unit for the cost of shipping. It looks new out of the box with all of the stickers still on the front. I took a chance hoping it would be something simple.
Thanks
Dan

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

**Curt Palme** · Posted: Mon May 25, 2009 4:33 pm Post subject:

Someone here had a similar problem, a high end Denon worked save for the surround functions. Turns out it was a cracked PC board.

I get about 50% success rate on 'customer return' units. A lot of times it's simply 'user error'. THe other 50% end up being techy problems due to some internal component issue, and I'd say about half of those are writeoffs due to expensive chips being bad.

right now I've got two high end Yamaha receivers here, one c/w remotes, that go dead intermittently. Will work fine for up to 2-3 weeks, then be stone cold dead. I've traced it down to the 'processor' boards, that house the CPU. I've resoldered bunches of stuff, flexed the board, blah blah, no dice. One ended up working for 3 months before it died again. Nice receivers, useless the way they are though.

I'm sure Mac (or myself) would love to take a stab at the Denon if you give up.

Brian Hampton · Joined: 22 Apr 2006 Posts: 1173

Hi,

I also don't fully understand (even though I had several cups of coffee) but...

I have a Denon 788 that I bought refurbished. It started having a terrible problem (loud noise in anything but "STEREO" mode.) I sent it for repair and it was good as new for a while and then a few weeks later the problem just came back.

There was only a few screws on the case and inside there was boards and stuff so I took it apart and re-seated things. It's been fine ever since.

It's a long shot but ... maybe you want to try re-seating boards. These newer AVR's have more boards (more modular) and maybe something is loose.

-Brian

drice1234 · Joined: 07 Oct 2006 Posts: 1309 Location: Allen, Texas

Maybe I do not really have a problem. As I increase the volume after the -40db mark the sound output goes up considerably. I had just thought that between -80db and -40db that I would have some sort of volume from the system and that this would not just be dead space. Whatever happened to volume just going from 1 to 10 (or 11 is you get the special Spinal Tap version of a receiver)?
Dan

**Curt Palme** · Posted: Tue May 26, 2009 12:54 pm Post subject:

Yeah, that's annoying. Keep in mind that -60db is almost dead silent. That was the noise floor back in good old reel to reel days, and -60 was considered excellent for a s/n ratio.

What kills me is that these manufacturers want you to think that 0 db is the level that the filmmakers want you to listen to the sound to, but they completely ignore the fact that the room and speaker sensitivities can affect the sound pressure by about 20 db. One Bose speaker has a sensitivity of 84 db, very insensitive, while a horn loaded pro cabinet can have a a sensitivity of 106 db.

bgotro · Joined: 07 Jan 2009 Posts: 4 Location: Whitby, ON

I was also going to say that I doubt I'd hear anything at all on my SSP (Anthem Statement D2) at -80db! I normally have audio levels at around -20db for movie/TV show watching.

"Audi Bill

drice1234 · Joined: 07 Oct 2006 Posts: 1309 Location: Allen, Texas

I went ahead a cranked the volume up and everything appears OK. A nice pickup of a $400 list receiver for $33 including shipping. I'am sure the person who bought and returned it was just like me and expecting sound in the first range of the volume control.