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Old 11-13-2017, 09:04 AM   #1
BaseballCap
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Default Behringer DDM4000

Got this DJ mixer very cheaply, has various faults. After power has been off a while, switching on lights ALL the LEDs and it wont boot. At this point, switch off then on and again and it will often (not always) boot, or at least boot partially.

When its running it mostly works, though sometimes the EQs don't. I found the sound also quite lacking in bass with all EQs at zero.

Inside there are no obviously bulging caps, but the switchmode PSU unit has quite a few "DECON" caps, which I understand are rubbish.

Thinking to replace these and see if any difference. Aside from that there is a processor board with dozens of very small electrolytics. It would take a while to replace every single one but I might try it.

Does anyone have any experience with this mixer? Reading online it seems they are more or less garbage, but I wonder if that's poor capacitors for the most part. The effects sounded good - when they worked!

Will also try a factory reset as well in case the settings got corrupted. Beyond that It might be destined for scrap!
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Old 11-14-2017, 01:56 AM   #2
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Default Re: Behringer DDM4000

Typical Behringer with PSU full of Decon caps. If it's an SMPS type, clearly those need to go first.

As for the control/mixer board - I would replace any electrolytic connected to an op-amp. I used Nichicon FW audio caps on the signal paths of a recent amp repair, and they cost pretty much the same as any other Japanese cap. So it made sense, even though I couldn't hear any difference in sound quality. But then again, the caps in the audio path of that repair were all fine.
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Old 11-14-2017, 08:07 AM   #3
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Default Re: Behringer DDM4000

you may open it up and blast the PSU with heat, then turn it on and see if it boots properly
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Old 11-14-2017, 10:54 AM   #4
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Default Re: Behringer DDM4000

I don't want to risk damaging the windings on the isolation or flyback transformer by applying too much heat, but its a fair point, sometimes bad capacitors behave better when warm..

Its only 12 DECONs on the board, shouldn't take me long to swap them out. I'll replace with whatever I have at home and test everything I pull out. Hopefully something will show low capacitance or a bulge at the bottom

If this doesn't get me anywhere I'll have to assess whether this is worth continuing with. Its one thing to replace some caps, but if these units are seriously flawed beyond cheap capacitors, Its probably not worth bothering with.

I'll report back when I've done the job, depends if I have the values in my supplies when I will be able to do that.

Its not too bad inside build quality wise, usual hot glue in various places, but the SMPS is in a metal box with the regulators clamped to the outer wall, and some nice RFI filtering.

The mixer came to me very filthy, but right now I will not be wasting any time on cleaning if its destined for the dump!

Last edited by BaseballCap; 11-14-2017 at 10:55 AM..
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Old 11-15-2017, 03:16 AM   #5
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Default Re: Behringer DDM4000

Unfortunately I pulled and tested each and every one of the 12 capacitors on the PSU board, EVERY single one tested absolutely fine and very close to their values. Now I didnt test them for leakage current, but I've found if modern electrolytic caps are bad you will see it in the capacitance reading.

No bulging underneath or leaking electrolyte. Starting to think this isn't going to be as simple as bad caps

There are many smaller 10uf or 1uf capacitors on the other boards, but as with these they are least visually fine.
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Old 11-15-2017, 05:54 AM   #6
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Default Re: Behringer DDM4000

Are you serious?

Those are replace on sight.

Quote:
There are many smaller 10uf or 1uf capacitors on the other boards, but as with these they are least visually fine.
Which means absolutely nothing. Don't overcomplicate this.

Quote:
After power has been off a while, switching on lights ALL the LEDs and it wont boot. At this point, switch off then on and again and it will often (not always) boot, or at least boot partially.
Like any other SMPS with craps in the aux/kickstart ckt...
So-called "unimportant small caps" are just as suspect as the big ones, perhaps more so- they bring on this irrational "they're small, they're OK" thinking.
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EOL it...
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Old 11-15-2017, 06:06 AM   #7
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Default Re: Behringer DDM4000

same capacitors as in this thread so yes just change them
https://www.badcaps.net/forum/showthread.php?t=58678
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Old 11-15-2017, 06:31 AM   #8
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Default Re: Behringer DDM4000

Id prefer to find the fault before I end up replacing every single capacitor. While that might be prudent for longevity, if the fault is not found to be capacitor related I will have wasted a lot of time on this.

The small caps I referred to were on the main mixer board, not a part of the SMPS. If I can get it booting properly and see some improvement from the PSU work, sure I'll go ahead and do every one I can find.

Finding them all in spec was disappointing and suggested to me they're not the problem. Someone has suggested to me they could be high ESR, I don't have a way of reading that unfortunately, but in the past found high ESR affected the capacitance reading.

To rule out the ESR I'll do all the caps on this SMPS module and see where I am.

As it is the mixer is unusable, if the fault is a processor or IC somewhere on the SMD board, its game over for me. I was hoping as has been suggested this is a PSU startup or power cleanliness issue

Last edited by BaseballCap; 11-15-2017 at 06:37 AM..
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Old 11-15-2017, 06:43 AM   #9
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Default Re: Behringer DDM4000

One comical point on this board. The 2 voltage regulators run very hot, so much so they are clamped to the metal box the board is in. 2 x 1000uf 85 degree capacitors are mounted right next to them, potentially to ensure after a few years use the mixer craps out and someone buys another!
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Old 11-15-2017, 10:07 PM   #10
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Default Re: Behringer DDM4000

Quote:
Originally Posted by BaseballCap View Post
Now I didnt test them for leakage current, but I've found if modern electrolytic caps are bad you will see it in the capacitance reading.
Usually yes, but not always. And this usually applies only for the bigger caps. For small caps, I've seen them show full proper capacitance and absolutely out-of-spec ESR. In fact, one of my very first few repairs was a router power adapter that wouldn't start up unless I heated the adapter up. When I changed the single small 50V, 47 uF "start-up" cap, that's when the adapter was fixed. I saved the original cap and a few years later after getting an ESR meter, I checked it: it showed 45 uF capacitance, but over 30 Ohms ESR, IIRC. Heating it up with a heat gun caused its ESR to drop down to less than 10 Ohms. So that explains why the power adapter would work when warm.

Thus, if anything, don't ever trust the capacitance alone of small caps. You can probably ignore the small caps on the mixer board for now, but definitely change all of the small caps in the PSU if you don't have an ESR meter.
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Old 11-20-2017, 04:09 AM   #11
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Default Re: Behringer DDM4000

Well, here we are, another case of crappy capacitors!

I replaced all 12 electrolytics on the SMPS board with mostly Panasonics, and a few Samwha. Re-assembled the mixer and it boots perfectly every time, all previous faults appear to have cleared!

At some stage I will get round to doing the processor board and main mixer PCB, but for now the mixer is working like new. Before it would fail to boot half the time, and when it did some features would be non functioning and weird symptoms like no bass on the outputs
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Old 11-22-2017, 04:18 PM   #12
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Default Re: Behringer DDM4000

Quote:
Originally Posted by BaseballCap View Post
Well, here we are, another case of crappy capacitors!
Who would have thought, huh?

The only good thing I can think of when I see the DECON name is rat poison.
Though on that note, I probably should recap my Behringer EPQ-1200 amp. It's full of those DECON caps too. I never recapped it because it appeared to work okay after finding the original fault - which was damaged component caused during shipping. But I don't use that amp at all currently, so it's not an issue. If I do find a use for it, I might recap it then.
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Old 11-22-2017, 04:29 PM   #13
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Default Re: Behringer DDM4000

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Originally Posted by momaka View Post
Who would have thought, huh?

The only good thing I can think of when I see the DECON name is rat poison.
You're not the only one who's made that joke! Here's another: DEceptive CONdenser.


About 10 years ago, had one of those real cheep worstbuy LCDs where 180 of those caps were bad, subminis too. The ones in the PS were next to and under heatsinks- had inverted-U ones. Told em get a new one. That POS didn't make it three years; started acting up little by little during colder seasons.

I should add that removing and testing questionable caps is misleading for yet another reason: When they're warm from desoldering, you get the "warm cap works better" when measuring ESR or other parameters.

Desolder it and check after cooling off, they'd measure worse than they already are, if that's even possible!

BBC- you've un-behringered that behringer, have fun!
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Old 11-22-2017, 04:37 PM   #14
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Default Re: Behringer DDM4000

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Originally Posted by kaboom View Post
You're not the only one who's made that joke! Here's another: DEceptive CONdenser.
Right you are! I stole that joke straight from kc8adu. He mentioned it once and I looked up the name Decon. Sure enough, that rat poison stuff came out, just as he joked.

Quote:
Originally Posted by kaboom View Post
I should add that removing and testing questionable caps is misleading for yet another reason: When they're warm from desoldering, you get the "warm cap works better" when measuring ESR or other parameters.

Desolder it and check after cooling off, they'd measure worse than they already are, if that's even possible!
Yes, sir, well aware of that, so that's exactly how I do them.

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BBC- you've un-behringered that behringer, have fun!
Lol. What can I say?

Designed in Germany
Made in China

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Old 11-22-2017, 04:47 PM   #15
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Default Re: Behringer DDM4000

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Originally Posted by momaka View Post
Lol. What can I say?

Designed in Germany
Made in China

Lo-lo-lol, troll-lo-lo!

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Old 11-22-2017, 04:51 PM   #16
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Default Re: Behringer DDM4000

Ooops, perhaps I should changed that...

Quote:
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Designed in Germany
Made in China
Fixed in *insert your country here* by Japanese caps
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Old 11-22-2017, 04:55 PM   #17
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Default Re: Behringer DDM4000

"Kaboom, it's fixed!"

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