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At our gig last night we where experimenting some cracking through the PA.
I started ruling out the possiable things it could be; cords, wired wrong. When We started shutting equipment down to figure it out (feedback buster, DCX, amps) we didn't try the eq cause the switch is in the back, but when we did it went away.
Before I through the thing away I want to make sure it is the eq. Does this piece of equipment break down frequently? (Behringer)

No time like the present to figure out how to use the DEQ2496.

K the manual 31 band eq has shit the bed.
So I plugged in the DEQ2496 (used on Ebay) that I got about 8 months ago and it powers up but thats it. Orange screen and all the lights are on from each button.
Does nothing out and nothing appears on the orange screen.
Do I have a bad Deq also??

Yes, you do.

That F***en sucks. I bought it 8 months ago and just plugged it in when I unpacked it to see if it powered up (ya she lit up) but never ran a signal through to verify.
180 in hole gone....I tell my wife that, I'll be eqing myself off the ground.

Chances are its a bad cap or three on one or both units. If you're not comfortable opening up and working on it, find a local electronics guy who works cheap to go through it and see if it's something simple. My local guy is $25/hr for stuff like that, perhaps you can find someone equally reasonable.

BrentEvans wrote:Chances are its a bad cap or three on one or both units. If you're not comfortable opening up and working on it, find a local electronics guy who works cheap to go through it and see if it's something simple. My local guy is $25/hr for stuff like that, perhaps you can find someone equally reasonable.

I talked to someone today about it and they don't want to tackle it because it would be to hard to pinpoint. He told me to take a look under the hood with a large magnifying glass and look for any cracks around the underneath of the circuit board around the areas that protrude to the other side.

Or go to my local stereo dr and get charged an arm and a leg (which I need to play drums ) to even look at it.

Just reading Dave Carter's DCX thread it looks like your problem might be same as his, shorting off the circuit board to the case, easy fix.

Also, for both you and Dave: the Behringer units have a reputation of the internal power supply being dimensioned too small for the needs of the unit, and with bad quality caps. Heat inside the unit speeds up degradation of caps that are already too small and not very good quality to start with. Once the power supply caps start failing, the power to the rest of the electronics is not very clean anymore which can lead to all kinds of issues, best case additional noise or frying egg sounds (similar to what happens with pins from the PCB shorting to the case), worst case complete failure of the device.

There's a PDF document in German floating around on the net with descriptions of how to modify the power supply on an ADA8000 (8 channel AD/DA convertor in 19" 1u). Stage 1 is upgrading the main caps on the power supply board, from 400uF to 1000uF or 1500uF, using good quality caps. Stage 2 is adding a small fan in front of the power regulators on the supply.

If the power supplies in the DEQ and DCX are similar, the same mods might be applied there. Not very hard to do, total costs in parts about $15 per unit. I intend to do this to my pair of ADA8000 and DEQ2496 as soon as the warranty expires.


Last but not least: it seems the power supplies for US units are dimensioned for 90-95V rather than 110-115V. Feeding them 110V will work, but generates a lot more heat in the parts that regulate power inside. Basically the difference between 90V and 110V is dissipated as additional heat. ADA8000 users have reported units running a lot cooler and living longer with a step down transformer that brings 110V down to 90V. Not sure if this applies to the DEQ and DCX as well.

I wonder if that could be part of my problem. I looked and didn't see any swollen or bulging caps in my DCX, but it is also true that the noise never seems to happen until after the unit has been running for a couple of hours, so the the heat build-up would make sense. Now I just have two problems... lack of tools and skills to re-cap the power supply and lack of ability to read German.

There is google translate, but it will still require typing the entire article in a language that you don't know. That's no fun, and Google doesn't do the soldering just yet.

I will see if I can get a picture of the ADA8000 power supply online. If it's different from the one in your unit, then I'd cancel the course German For Dummies if I were you

Here's the relevant bit of the ADA8000 power supply. The large capacitors are too small, the regulators run hot.

So are you saying that the caps I circled are the ones that would need to be replaced?

I think so. They need to become larger capacity, that will not fit the original board. The author of the article added a small separate board with the larger capacitors, and a separate regulator to make 12V for the fan. Here's the completed mod on an ADA8000:



Left: small fan added. Just below that: caps removed, wires to new cap board installed (red/blue/black).

Right: the new board, installed upside down (don't know why)

Top: some foam on the cover to prevent the new board from shorting when the cover is installed

Parts list:
2 x capacitor 1000uF 35V
1 x capacitor 470uF 35V
1 x capacitor 10uF 16V
1 x regulator UA7812
1 x small fan 12V, 40 x 40 mm
1 x small piece of general purpose board (what's that called in english?)
some glue, small gauge flexible wire in three colors, foam to go between board and cover

Total price estimated at 15 EUR

AntonZ wrote:If the power supplies in the DEQ and DCX are similar, the same mods might be applied there. Not very hard to do, total costs in parts about $15 per unit. I intend to do this to my pair of ADA8000 and DEQ2496 as soon as the warranty expires.

So how long until your warranty expires? I'd love a well-documented, step-by-step tutorial since I have never done any soldering or electronics work aside from the filters in my DR cabs. All that PCB and those caps everywhere look very intimidating.

I just got my ADA8000's, so that will be another year from now. Warranty on the DEQ has expired though, so I could start on that one. I haven't opened the cover yet and it is currently racked, so I do not know if the power supply in there is the same as the ADA8000.


Edit: I just took the DEQ out of the rack and opened it. It has a switch mode power supply, which is completely different from the more conventional supply in the ADA8000. So the suggested mods from the ADA8000 do not apply here. Sorry for the confusion.