4-Pin XLR Power Cable for Tangent SM12

[jdragonash]

I recently acquired a Tangent SM12 Mixing board but it has no power cable. There is a male 4-pin XLR jack wired to a ON-ON switch, looks like 5A 120VAC. When researching about how to make a power cord for this, I came across some discussion about 4-pin XLR being used for video camera gear that took DC, and a lot of the power cables with 4-pin XLR connectors come with AC/DC converters. The 4-PIN male xlr jack is wired with pin 1-Yellow, pin 2-Black, pin 3-Red.

Can I just solder a 4-pin XLR Female connector onto the bare end of a 300V 16AWG 3-conductor power cable that I have, Green/White/Black? If so, where would I want the green, white and black wires?

Another concern is that the male 4-pin XLR jack seems to be grouped with two other 1/4" audio aux inputs. Other Tangent mixers that I've seen have clear indication of power requirements marked near the jack.

 

[user 130681]

NO!
Look at the schematic, find out what voltage it requires, probably +-15volts DC and wire a power supply accordingly to a four pin XLR female plug.

 

[jdragonash]

NO!
Look at the schematic, find out what voltage it requires, probably +-15volts DC and wire a power supply accordingly to a four pin XLR female plug.

Thanks for reply. I should have mentioned that I have not been able to find a schematic for this unit. I tried a 4-pin 12V DC power supply but it only had two pins wired.

 

[Brian Roth]

Any other pix of the rear panel. or of the entire unit?

Bri

 

[Khron]

And seeing what the four(?) wires connect to, might also help.

 

[Brian Roth]

Tangent was a reputable company....I've encountered more than a few of their mixers and consoles over the decades. Decent gear.

I am puzzled by the silk screen markings in that rear panel pic, however. I cannot imagine Tangent randomly slapping a power inlet in that location seen in the pic. And then there is the 1/4" jack with no label??????

I wonder if the model shown was some sort of "sidecar" "add-on" for a different mixer. Hence, my request for more pix.

Bri

 

[jdragonash]

The 4-Pin XLR is connected to the power switch on the front side. Only three wires are present-- pin 1 Yellow, pin 2 Black, pin 3 red. The Red and yellow connect to what looks to me like an ON-ON switch with six solder lugs, only four of which are wired. The black wire connects to the monitor module. Adding another photo of those connections.

 

[user 130681]

You require a dual power supply with a +ve 15volt and -ve 15volt output at about 1Amp.
The black wire is ground or common.
Red is +ve 15 volts and yellow -ve 15 volts that is my educated guess. To prove it, on the preamp boards there are two capacitors, circled in my picture.
Check for continuity between capacitor A +ve terminal and the red wire, likewise capacitor B -ve terminal and the yellow wire. There should be continuity unless there is a coupling resistor in series with them, in which case there will be continuity at the supply side of the resistor.
Hope that helps.

 

[nsalis]

I'm not familiar with Tangent mixers, but I suspect that previous speaker Jon S is right. Attached is the rear view of another Tangent mixer. Here you can see the same XLR 4m panel socket, but this time correctly labeled DC Power.

Incidentally, desktop power supplies with +/- 15 VDC are not easy to find. The best products (lowest noise floor) have linearly regulated power supplies, but they're heavy, bulky, and expensive. Since your mixer is not a particularly sophisticated product, a switch mode power supply should suffice. E.g. XPpower model PCM50UD08 (Digi-Key Part Number PCM50UD08-ND; datasheet see enclosure). You would have to remove the 5-pin DIN connector and attach an XLR 4f.

Nick Salis

 

[user 130681]

Noise floor doesn't matter as this type of mixer uses a balanced input and balanced supply rails and is essentially noise cancelling by design.
If you use two 15v DC power supply "bricks", wire them in series and you will have the required supply.

 

[Brian Roth]

Since this seems to be a custom/prototype/one-off we can't ASSume anything,

I've seen gear with a 4-pin XLR "power connector" which merely connected an external power transformer into the device. Rectifiers, filter caps, etc were in the unit. Sontec anyone??

@ jdragonash

Some great advice in this thread, but it seems you need an Olde Man Tech guy <g> to sort through that power connector wiring to ensure that the least amount of Magic Smoke is released. That color code is odd.... Black as 0V/common makes sense. The other colors are off the wall.

I don't have a CLUE what power connector pinouts Tangent would have used used as an in-house standard.

Bri

 

[jdragonash]

Thank you Brian and Jon S et al for helping me out here. Now that I have some idea about the likely power requirements, I have been looking around and saw that perhaps this Gyraf mini psu for the PQ1549 with +/-15V output might work? Likewise, Pete Millett has a bipolar DC power supply kit with a PCB mount toroidal transformer (PS1525) that seems to have the necessary outputs.

The XPpower model PCM50UD08 doesn't seem to be in stock at mouser, digikey, and at $133 and a four month wait, I'm looking at other options. Two 15V DC bricks wired in series seems like the most practicable option at this point.

That said, yes, I'm going to hold off until further elaboration before I start hooking everything up. Going to take advice and check for contiuity as suggested above. I'm still really confused about the labeling on the panel. And that mystery 1/4" jack has just one blue wire, which goes to the monitor module.

 

[nsalis]

"I'm still really confused about the labeling on the panel."

That alone wouldn't worry me that much. The XLR 4m panel plug is placed in the "INPUTS" field. Of course, as a technician, one could argue that the input for a DC power supply is of course also an "input". The fact that the XLR 4m chassis plug is mounted with rivets (rather than screws) that look the same as the rivets on other XLR chassis sockets and plugs reinforces one's assessment of its original condition and that it is not a subsequent conversion.

At the moment, what irritates me the most is the unlabeled 1/4" panel socket next to the XLR 4m panel plug. And that the former is said to have only one (1) wire soldered on. This is at least unusual, but it can work, since the shaft of the 1/ 4" jack is galvanically connected to the mounting plate and thus to 0VDC. You would at least have to tell us where exactly (to which component) the wire leads.

Perhaps Brian Roth is right and the mixer is a special version to complement another piece of equipment to which it was connected via an XLR 4-pin and 1/4" jack cable.

As a first step, you must definitely take the measurements that Jon S recommended. Never connect any power source beforehand. You said you already connected a standard 12VDC power supply with XLR-4 cable jack. These are wired so that pin 1 has 0VDC and pin 4 has 12VDC. Since pin 4 is unconnected on your socket, you were lucky.

At the moment, however, I have to agree with Brian Roth: We don't (yet) know enough to allow us to electrify the mixer.

Let us know the result of your measurements before you take any further steps.

Nick Salis

 

[jdragonash]

Okay, I have checked for continuity between the capacitors indicated by Jon S and the corresponding wires, and there is continuity in both instances, red wire and capacitor A and yellow wire and capacitor B, respectively.

red wire and Cap A: 10 on + lead / 836 on - (106 ohms on +)
yellow wire and Cap B: 479 0n + / 11 on - (110 ohms on -)

Forgive me if those numbers don't make sense--I'm still learning how to interpret the multimeter, and I have and analog Sunwai and a digital one for automotive, so I'm not sure if I had it dialed up correctly.

 

[nsalis]

To make sure I understand correctly.

1. Assumption: The power switch was switched on during your measurements.
   
   
2. Panel jack XLR-4m, pin 1, yellow wire to capacitor "B", negative pin = 11 Ohm.
   
   
3. Panel jack XLR-4m, pin 1, yellow wire to capacitor "B", positive pin = 479 Ohm.
   
   
4. Panel jack XLR-4m, pin 3, red wire to capacitor "A", positive pin = 10 Ohm.
   
   
5. Panel jack XLR-4m, pin 3, red wire to capacitor "A", negative pin = 836 Ohm.
   
   
6. Question: What do you mean by saying "106 ohms on +"
   
   
7. Question: What do you mean by saying "110 ohms on -"?
   
   
8. Question: What do you measure from panel jack XLR-4m, pin 2, black wire to capacitor "B", positive pin?
   
   
9. Question: What do you measure from panel jack XLR-4m, pin 2, black wire to capacitor "A", negative pin?
   
   
10. Question: What do you measure from panel jack XLR-4m, pin 2, black wire to any housing part that is made of metal?
    
    
11. During your measurements you had the red measuring lead at one measuring point and the black measuring lead at the other measuring point. If you repeat the measurements with swapped leads: Do you get the same results or does something change (and if so: what?)
    
    
12. Question: Where exactly does the blue wire soldered to the unlabeled 1/4" jack go?
    
    
    
    
    
    
    
    Nick Salis

 

[jdragonash]

Noise floor doesn't matter as this type of mixer uses a balanced input and balanced supply rails and is essentially noise cancelling by design.
If you use two 15v DC power supply "bricks", wire them in series and you will have the required supply.

I've finally got around to getting this ready to try out and wanted to double check my interpretation of your suggestion. So I have two AC laptop adapters (Mouser #: 209-VEC40US15 ). I cut the end off (not the end that goes into the wall, but the other end, after the brick. Each has two conductors, one on the inside which is shielded by white plastic and constitutes the positive, and the other that surrounds it, which I assume is the negative. Let's call them adapter A and adapter B. I took the positive from adapter A and soldered it to the negative of adapter B, leaving me with three total: the positive of A and the negative of B, and the composite wire. These three wires I soldered into the corresponding pins based upon the suggestions for how the power jack is wired up in the mixer: Pin 1 Yellow Negative ; Pin 2 Ground; Pin 3 Red Positive which corresponds to the aforementioned educated guess of the wiring for the mixer.

And so now I have at one end of the cord a 4-pin XLR with 1 positive, 2 ground, 3 negative, and at the other end two bricks, each of which will be plugged into the wall socket?

 

[jdragonash]

To make sure I understand correctly.

1. Assumption: The power switch was switched on during your measurements.
   
   
2. Panel jack XLR-4m, pin 1, yellow wire to capacitor "B", negative pin = 11 Ohm.
   
   
3. Panel jack XLR-4m, pin 1, yellow wire to capacitor "B", positive pin = 479 Ohm.
   
   
4. Panel jack XLR-4m, pin 3, red wire to capacitor "A", positive pin = 10 Ohm.
   
   
5. Panel jack XLR-4m, pin 3, red wire to capacitor "A", negative pin = 836 Ohm.
   
   
6. Question: What do you mean by saying "106 ohms on +"
   
   
7. Question: What do you mean by saying "110 ohms on -"?
   
   
8. Question: What do you measure from panel jack XLR-4m, pin 2, black wire to capacitor "B", positive pin?
   
   
9. Question: What do you measure from panel jack XLR-4m, pin 2, black wire to capacitor "A", negative pin?
   
   
10. Question: What do you measure from panel jack XLR-4m, pin 2, black wire to any housing part that is made of metal?
    
    
11. During your measurements you had the red measuring lead at one measuring point and the black measuring lead at the other measuring point. If you repeat the measurements with swapped leads: Do you get the same results or does something change (and if so: what?)
    
    
12. Question: Where exactly does the blue wire soldered to the unlabeled 1/4" jack go?
    
    
    
    
    
    
    
    Nick Salis

1. Yes, the power was switched on.

2. Yes, 11.3 is where it stabilized. That’s with the red lead on the yellow wire where it is soldered to the lug for pin 1 at the internal side of the XLR-4m panel jack. 11.3 is the reading with the dial of the multimeter set to Ohms 200 (the lowest possible setting, 2000K being the highest).

3. When taking this measurement, with the dial set to 20K, the number kept climbing, initially registering 1.48 and rapidly going up until it reached about 5.65. By rapidly I mean maybe 10 seconds to go from 150 to 300, and about 15 seconds to get up to 550, at which point the numbers kept climbing but at a diminished rate of increase.

4. Yes.

5. Yes.

6. I'm not sure. I tried to recreate the scenario just now since it's been a few months, and I don't know what I meant in that paranthetical about 106 ohms on + and 110 ohms on -

Q7-12 -- I will have to continue this tomorrow and will reply when I run those measurements.