Rather than reply to the million page long thread I'll just link it.
http://srforums.prosoundweb.com/index.php/t/9398/6617/OK. More bad news/good news depending on how you look at it.
Upon setting up for a show last week I had the frying bacon rear it's ugly head again. I thought I had solved it initially. Boy was I wrong.
The frying bacon sound was intermittent and would start with out warning. And note, it has absolutely nothing to do with being to close to the metal frame with stuff grounding out to that. Nothing.
The problem is the ribbon cable as Ivan had found previously with his units. After much pushing and prodding I narrowed it down to that. The kicker is, I can't for the life of me figure out specifically what problem with the ribbon cable causes it. It seems that the cable is glued down from the factory. When I first opened my unit, that glue had been undone by either vibration, temperature changes, or improper application. I didn't bother to re-glue it, but tucked the cable in neatly which mostly immobilized it.
Well, after some more shaking around in a rack for a month or so, the cable wiggled loose again. It seems that when the cable moves it causes the noise... I'm not exactly sure why. I examined the header and the point at which the cable is "pinched" or crimped on to the teeth of the header. I could see no visible issues. Looked like every other IDE hard drive style ribbon cable I'd ever laid eyes on... and those IME infrequently go bad with light handling.
The weird thing is when the cable moved independent of the chassis/boards it caused the issue. If it stayed in a particular spot I could elicit the frying bacon sound. If I jiggled it quickly I could hear pops/crackles at very high amplitudes +15 or so dBu. It was fairly random though... moving back to the same posistion would not always cause the frying bacon sound.
It is my guess that the ribbon cable has either: a worn connection, an improperly crimped end, or a break/short somewhere along it's length. Bad ribbon cables seem to be a thorn in the side of modern electronics... from what I've read of other manufacturers issues... though, IME I have had only one or two go bad on me in about 10 years of working with computers.
I can't tell for sure (I'm no electronics expert) but I think the cable is a digital connection. The noise seems digital in nature and after talking to a few local EE guys the thing that a bad ribbon cable could cause communication errors and bit error rates to go up causing the noise floor to rise. That would explain why it still passes audio with the frying bacon noise in the background. That is a total guess though.
I used hot glue to fasten the cable down... And I used it quite liberally. I also reinforced the connection point to the I/O daugther board with hot glue. The cable is completely immoble now. I can shake, smack, drop the unit with zero ill affects. No noise, no snaps crackles or pops. Since the thing is out of warranty anyway I tossed it down the basement steps a few times. Still works like a charm.
It is sad that such a great unit otherwise has to be hampered by a faultly cable that Behringer probably buys wholesale off the same suppliers as everyone else. It's probably a cheaper part but who knows.
P.S. While I still consider this a good value if you don't need absolute reliability I will discontinue purchasing these. I have 3 right now. Two are doing EQ for my monitors and one is doing EQ and xover for my side fills. Only one has exhibited the frying bacon sound.
For me they are non-critical. I *could* get buy running the sidefills in full range and EQing the monitors with the graphic. It's inconvenient and not optimal... but I've seen worse failures. For my FOH, I use a dbx DR260, and while I hate the front panel interface, the thing has been rock solid reliable for me. I would not have it any other way as my FOH cabinets require biamping, delay, and param EQ.
As time and money allows I'll probably upgrade to something like a DR480/xilica/Sabine/Protea. I wouldn't recommend the Behringer unit unless you have a risk mitigation plan or are a weekend warrior without much liability. One of these on FOH could be a dealbreaker if it went down and no backup was available.
Edit: clarity