Pin One Problem on DL1608

[WK154]

RR don't put this under auxes!
I didn't think I would see this showing up in any new Kit, but Mackie has done it. I misplaced my old hummer so I had to wait for the parts to arrive and they did today. Placed one lead on chassis (the one you have to bring out by the PSW connector area) and the other to any  XLR Pin 1 or sleeve on the Auxes and it hum's like a bumble bee. Need any more proof? I'll record it later. The other power supplies fixed the problem. Lucky for Mackie and those who bought a DL. Let's see if Mackie will ante up and send out replacements? APX has the correct PSW or certainly can provide it. Probably should notify Mackie officially and wait for their excuses. Mackie Lurkers?

[RoadRanger]

Are you trying to tell us that you have found a power supply that has the AC ground connected to the minus but doesn't have pin 1 issues? I'd love to be wrong in my belief that the noise problem is inherent to the tying together of the AC ground and the minus in the power supply !

For those wondering what the hell he's talking about (and for the Mackie "engineers" who seem to be oblivious):
http://pin1problem.com

[WK154]

I guess you haven't been understanding the posts. That is exactly the problem Safety ( Chassis) ground on the DC power return. It is a direct execution of what is called common impedance coupling.  The noise is also fed to the DC to DC converters, 48V, +- 15V and 3.3V come to mind all from 12V DC. Why don't you try it with a hummer?.

[RoadRanger]

I'm just not following you. If the problem is as I said how can any power supply swap fix it assuming said power supply still brings the safety ground out to the mixer via the minus lead?

[WK154]

Are you trying to tell us that you have found a power supply that has the AC ground connected to the minus but doesn't have pin 1 issues?
No where did I make that statement?
If the problem is as I said how can any power supply swap fix it assuming said power supply still brings the safety ground out to the mixer via the minus lead?
Because the power supplies don't bring the safety ground to the minus lead into the mixer (except for Mackie's). It's called isolation. If you want to keep the chassis from floating then you need to tie it to safety ground but not thru the power supply and in as direct a path as possible and after the DC to DC converters. You cannot eliminate ground currents into other devises that are attached but you can minimize the effect on their performance. As someone once said "electrons don't read schematics".

[Topsøe]

@WK154
Can you make a sketch ?

[RoadRanger]

No where did I make that statement?

You seem to be reluctant to tell us which particular supplies you are testing and how they differ from the "stock" supply.

Because the power supplies don't bring the safety ground to the minus lead into the mixer (except for Mackie's). It's called isolation.

Some Behringer mixers with external supplies use a three wire connector so that the safety ground can be brought into the mixer separately from the minus (as is proper). Your contention seems to now be that Mackie could ship power supplies with no connection between the minus and safety ground. I doubt they could do that and still pass CE tests .

[WK154]

RR: I must have ESP, I answered your question before you asked it!

"You seem to be reluctant to tell us which particular supplies you are testing and how they differ from the "stock" supply.
My Quote from prior post
    Because the power supplies don't bring the safety ground to the minus lead into the mixer (except for Mackie's). It's called isolation."

I hope that answers your question.
I have 4 supplies that I've used for testing including the original. I will publish the results soon. Real world numbers not theory or FUD.

Model #1206 LCD AC Adapter 3 prong (Amazon 9.39 + 8 for ship)
Model ST-C-075-12000600CT 2 prong (Internet ~10.00 inc. ship)
Xpower Model 305D lab supply (69.00)
APX SP50Q912LR Mackie original (~70.00 from a post)
I'm sure the model # will make a difference (or at least shut you up).

BTW these are only part of the power supply used to get around bureaucracy testing. There is no 12V used in the mixer except for the intermediate stage of several power supplies (DC to DC Converters). 48V phantom power, 5V for iPad charging, 3.3V for digital logic, +- 15V for the analog section. The grounds from these are tied to chassis ground and chassis ground should be tied to AC safety ground. That's the way it's been done for decades. The DL pulls about 1.5 - 2.5 amps @ 12V depending on loading for those interested.

If you purchase a supply be certain that the connector is a 5.5mm/2.5mm variety. RFI magnetic s on the cable would also help. As to the approval by such agencies as CE or UL etc. there are over several hundred million of these out in the world. CE and UL think there safe. There was a post regarding the power connector being unreliable and having to spread the pin to make it work. Loose the retaining nut it's the cause. The replacements don't have one. It won't let the connector contacts centering work properly. If your really concerned about someone pulling out the power cord, well that's why God made gaffer tape.

If your impatient about the frequency of my posts rest assured that this is NOT at the top of my priority list.

[RoadRanger]

Thanks! I'll put my tooth extractor away now .



... or not, still can't find the listing for this one:
Model #1206 LCD AC Adapter 3 prong (Amazon 9.39 + 8 for ship)
That's the one I'd be most interested in - a 3 prong with no connection between the output and safety ground.

And it doesn't matter if the supply is CE approved (although that's a necessary start), the whole shebang has to pass as a system. I walked a product with a line wart through CE testing just the summer before last . It was a home medical product, the testing requirements were particularly tough .

[WK154]

For medical products that's another can of worms. That's why you see a lot of legalese about use of products not fit for life dependent use. So what medical use have you found for the DL? Colonoscopy? The Amazon product for 9.39 comes from several vendors and Amazon doesn't list their model # that's why I said it's pot luck. I e-mailed the folks at APX who have been quite helpful to see if they have a model SP50D1R912LR where the L stands for low ripple/noise. To date the 2 prong unit has the best real world results (excluding the lab supply).

[WK154]

BTW, did that current measurement include the iPad charging? That 3A supply I just ordered is cutting it a bit close if there's another half amp draw for charging
Why would you order a 3 amp supply when all the units I have been working with are 60Watt (5amp) or better?
So much good all those part # did!
We'll see if the supply can handle it. It'll be more efficient. Need to make sure it stays cool.

[WK154]

Topsøe Can you make a sketch ?
A sketch of what?

[RoadRanger]

Why would you order a 3 amp supply when all the units I have been working with are 60Watt (5amp) or better?

Because you said the highest you measured was 2.5A, it was only $9 shipped, and just because I could . Do you think you've cornered the market on orneriness ?

[RoadRanger]

To date the 2 prong unit has the best real world results (excluding the lab supply).

How would it do in the RF radiated, conducted and susceptibility tests? Leakage current testing? If Mackie was to switch to it they'd have to pass those first . Again, I suspect they went with the safety ground tied to the minus because they had to.

[WK154]

No different than the hundreds of million Laptops and LCD panels currently using these supplies.