DCX Woes

[John H]

You say it happens after its been operating for some time? I wonder if it might be thermal related....

[Radian]

Do please take into account when figuring Behringer failure rates:

They sell a gabillion times more product than the next guy, to a market that is very likely to complain openly about its faults. You hear a lot of flak about because its been around forever and almost everyone in the market has heard something about them. It comes with the turf.

-Radian

[David Carter]

Do please take into account when figuring Behringer failure rates:

They sell a gabillion times more product than the next guy, to a market that is very likely to complain openly about its faults. You hear a lot of flak about because its been around forever and almost everyone in the market has heard something about them. It comes with the turf.

Good point. I've had several Behringer products, and this is the first one that's ever given be trouble. Plus, from what I've read, I'd have to really get into big money before I could get anything that's not going to be prone to issues of some sort. I feel that if I can isolate the source of the problem and fix it with the help of all the knowledgeable folks around here, I'll have a more reliable piece of gear plus I'll be a lot more prepared to address similar issues if they ever arise with other gear.

Contrary to most of you guys, I'm not at the point where I'm doing shows and making money with any of this. At this point, this is a 100% for-the-fun-of-it hobby which is used 99% of the time for my garage band that doesn't do paying gigs either. For me, it's all about having fun and learning about stuff that has fascinated me since I was a kid. My gear isn't paying for itself, but it doesn't have to meet the demands of clients and paying gigs either. So, while I want something reliable, it's not going to kill me if I have to do a little experimentation and work to achieve that reliability. In my situation, that is preferable to going out and spending 3x more money to ensure a rock solid product.

[David Carter]

You say it happens after its been operating for some time? I wonder if it might be thermal related....

So, if I want to test this, I should be able to run recorded music through the mixer and EQ into the DCX for several hours but leave the power amp turned off to avoid having to listen to it the whole time. And as long as the signal level going into the DCX is high enough, I should be able to get it warmed up that way, right? Then just power on the amp occasionally to see if it's behaving or not?

[Radian]

As Spock would say, "That would be logical."

The unit will warm up over time just by virtue of its power supply alone, but If you want to speed that up, throw in a few parametric slopes that drive the "CPU available" down to just a few percent while running a signal through it.

[bgavin]

Use a hair dryer.

In the last century, we used hair dryers and cans of Freon to locate intermittent wiring problems in main frame computers.
This is last hurrah bug shooting, but effective when needed. Over heating the DUT is possible, so use caution.

Please do a Google search for "frying eggs" and your unit.
There are several known/easy fixes for the problem. One of the posters mentioned this on the first page.

Pluck the low hanging fruit first. Most of the time, this is the fix and you can move on.

[David Carter]

Use a hair dryer.

In the last century, we used hair dryers and cans of Freon to locate intermittent wiring problems in main frame computers.
This is last hurrah bug shooting, but effective when needed. Over heating the DUT is possible, so use caution.

Please do a Google search for "frying eggs" and your unit.
There are several known/easy fixes for the problem. One of the posters mentioned this on the first page.

Pluck the low hanging fruit first. Most of the time, this is the fix and you can move on.

Yes, I've done the "frying egg" search multiple times and read all kinds of stuff. So far, the only solution that seemed within my abilities was to put non-conductive material under the XLR board. As described in the first post of this thread, I've already done that. I am not sure whether or not that has cured it or not. It has only been in the last few days that I have tried to deliberately reproduce the problem in a more controlled environment. So far, it's behaving. I just have this nagging suspicion that I haven't seen the last of it, so I've been trying to identify other low hanging fruit.

[David Carter]

If I want to pull apart the ribbon cable connections and reseat them, what is the best way to do that without damaging anything. They all have a heavy dose of glue holding them together right now.

[bgavin]

You are fast getting in over your head.

In your shoes, I would let sleeping dogs lie, and see if the interposer between board and chassis is your fix.

[David Carter]

You are fast getting in over your head.

In your shoes, I would let sleeping dogs lie, and see if the interposer between board and chassis is your fix.

That sounds like a good idea. I'll wait and see.

[WB]

so I've been trying to identify other low hanging fruit.

http://img522.imageshack.us/img522/593/img1281dh.jpg

In this picture of yours, try sanding the contact tab and the inside of the cover you removed for better grounding.


I'm going to be opening my DCX shortly because the last 3 times of use it made the exact same sound as you described, except it starts about 5 minutes after power up, and lasts for about 15 minutes. I was lucky because all 3 times I arrived an hour early to sep up. Otherwise, the DCX has been fine for a year and a half. The last time, I set the rack on its side and banged it with my fist, and could induce the noise and alter it. Leads me to think it could be mechanically related as far as connections or grounding possibly.

The sanding the tab idea I found on the internet years ago when researching the frying egg sound with the DEQ. I used to have that sound and did a couple fixes and it never came back. BTW, the two sounds were slightly different. The DCX was a scratchy static sound, the DEQ was exactly like eggs frying. The DCX was loud and obnoxious, the DEQ was closer to the noise floor.

[bgavin]

The last time, I set the rack on its side and banged it with my fist, and could induce the noise and alter it. Leads me to think it could be mechanically related as far as connections or grounding possibly.

This is a huge leg up in diagnosis.
Tapping also works well for finding microphonic tubes.

The problem with sanding base metals to a bright finish is the inevitable return of rust or corrosion, and the problem.
A conductive grease will make the contact anaerobic and avoid rust.

The frying eggs sound is signal modulation which tells me something electrical is rapidly/randomly changing value.
My thoughts would be first directed at those craps I saw on the boards.

[WB]

Finally got around to opening my DCX.

http://web.me.com/wb12/iWeb/WB%20/DCX24 ... G_1530.jpg

Found some burn marks where the grounding tab contacts the inside cover.

http://web.me.com/wb12/iWeb/WB%20/DCX24 ... G_1529.jpg

I sanded the contact surface and tab, also bent the tab up to give it more tension.

http://web.me.com/wb12/iWeb/WB%20/DCX24 ... G_1535.jpg

Did one gig with it so far and the static was gone.

[Scott Brochu]

I opened up my DEQ and found a cap that was leaning over in the little box. What would cause this and is this an easy fix for me? I will go in with a soldering gun if need be.
But can I get away with re soldering or does it have to be replaced, and if so how do I find the replacement? I have access to under neath the board.

[Radian]

I opened up my DEQ and found a cap that was leaning over in the little box. What would cause this and is this an easy fix for me?

Could be blown..or just bumped during assembly.

Decent info here: http://www.repairfaq.org/sam/captest.htm#cttes for tinkering in there.

Would that be dope if you recap it and bring it back to life! $$$$