Mating Dell DA-2 and Pico power supplies

PSUs: The source of DC power for all components in the PC & often a big noise source.

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reddyuday
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Mating Dell DA-2 and Pico power supplies

Post by reddyuday » Fri Sep 04, 2009 7:53 am

I have acquired a Dell DA-2 AC-DC powerbrick and PW-200-V pico power supply, but I am flummoxed by their connectors.

Is there a pre-made Molex plug that fits into DA-2's receptacle connector?If not, can I replace the existing DA-2 connector with some other receptacle? For instance, there are 8-pin ATX extension cables such as this one. One should be able to salvage the connectors at the two ends of the cables to make a mating combination.

Thanks for your help.
Uday

Edit: In the thread Antec NSK1300 with PW-200-V, Eitheta speculated that the Molex plug 39-01-2081 (8-position panel-mount connector) should be able to fit the DA-2 receptacle. However, the data sheet for this connector shows that the pin 1 housing is square, whereas the DA-2's pin 1 is round. So it doesn't seem to me that this plug would fit.
Last edited by reddyuday on Sun Oct 11, 2009 7:14 am, edited 4 times in total.

ryboto
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Re: Mating Dell DA-2 and PW-200-V

Post by ryboto » Tue Sep 08, 2009 5:20 am

a portion of the molex connector from a 24-pin female motherboard plug will fit the DA-2. The rounded pin on the DA-2 fits fine in the square of the other, and the rest of the pins are the proper matching shapes. Only issue I ever had with this method was voltage loss. I had a huge loss of potential across the connector, I ended up removing them in favor of some screw-type terminal connectors, and I've got almost zero voltage drop over the connection.

reddyuday
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Post by reddyuday » Wed Sep 09, 2009 9:15 am

Thanks Ryboto. That would have been an inexpensive solution but I didn't pursue it because I am no good with soldering/desoldering or to cut out a section of the ATX socket like Eitheta. I am pursuing the extension cable idea instead. I am also wondering if the voltage loss you experienced might have been due to incompatibilities between the DA-2 connector and the ATX connectors. Using ATX connectors uniformly might avoid that problem.

I will try to put down here enough detail so that others can make use of this info.

The ATX connectors are all Molex Mini-fit Jr type connectors, series 5556 for female connectors and series 5558 for male connectors. So, the two ends of the extension cable would have connectors of these types. This Playtool web page on "All about the various PC power supply cables and connectors" is a very good resource for finding out about all kinds of connectors and their specs.

I am going to do a little more work than just using the connectors from the cable I mentioned in the earlier post. Who wants gaudy white acrylic hanging out at the end of power supply cables?

For the female connector that goes at the end of the DA-2 cable, I am planning to use something like this AC Ryan 8-pin Connectx connector at performance-pcs.com. (AC Ryan sells all kinds of connector housings in various colours. A modding kit has a whole bunch of connectors and seems like good value for money. If I knew enough initially, I would have bought one of these kits, which also include two crucial pin remover tools. As it stands, I bought the pin remover tools separately, from an eBay shop called Sata City. They were made by OKGear.)

The 8-pin female connector has to go at the end of the DA-2 cable. The wires have to be stripped at the ends and connected to 'crimp terminal' pins. Both performance-pcs.com and kustompcs.co.uk sell these pins. (Look for "ATX" or "Mini-fit Jr" female pins, not "Molex pins". In the normal parlance, "Molex connector" means only the peripheral connector, even though Molex made almost all the connectors we use inside a PC case.) I have never done any crimping. So the first step was to learn about it. The Society of Robots "wire connector tutorial" is a good place to start. I am planning to borrow a pair of crimping pliers from my department workshop. Once done, these terminals will be inserted into the 8-pin female connector.

For the other side, I will use the Akasa 8-pin extension cable AK-CB8-8-EXT . One end of it is the 8-pin connector, which will be housed at the back of the case. The other end of it is a 4+4 connector which we have no use for. The idea will be to strip out the 4+4 connector, and join the +12 and GND wires to the PW-120's +12 and GND wires. I haven't yet thought about how I will do that. I might just end up doing some soldering after all.

The Playtool web page mentions 6Amp as the current rating of the Mini-fit Jr connectors. So, we get 3 * 6 * 12 = 216W of power safely passing through this connection.

reddyuday
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Post by reddyuday » Mon Sep 14, 2009 11:18 am

reddyuday wrote:I am planning to borrow a pair of crimping pliers from my department workshop.
Ran into a couple of problems. The crimp tool from our workshop was quite bad; it wasn't meant for Molex connectors. So I am planning to buy a crimp tool. The only one available in the UK seems to be a FrozenCPU tool for about 20GBP at scan.co.uk. The US seems to provide much more of a choice. I think the wires are about 16 or 18 AWG. So we need a tool that covers that range.

The generic connectors that I got from eBay were too crude. I ordered an AC Ryan modding kit now. Again, in the US, you have a much more choice. performance-pcs.com seems to sell all the AC Ryan connectors (look under DIY -> Connectors).

reddyuday
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Post by reddyuday » Mon Oct 05, 2009 9:46 am

No progress yet. I dithered on spending 20GBP for a Molex crimp tool. So, I got our workshop technician to help me with crimping using his tool. In the end, we managed to put the 8-pin Molex connector at the end of the DA-2's cable.

However, I probably screwed up the next step. I used the same pin configuration as Dell did (with pins 2-4 positive and 6-8 ground) and didn't notice that this is the opposite of ATX (pins 1-4 for +12V and 5-8 for ground). So, I ended up shorting the 'remote' trigger to +12V instead of ground. Only briefly perhaps, but the brick doesn't turn on any more. Duh.

I am going to get another Dell brick and use Ryboto's mating method (to a section of the 20-pin ATX connector).

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Post by reddyuday » Tue Oct 27, 2009 9:08 am

I got a new Dell brick. Also, independent tests revealed that PW-200 might not work for my motherboard. So I swapped it for a PicoPSU-150-XT. Then I did the mating with standard extension cables as follows.

Inventory: A 20-pin ATX male socket has two regions where a Dell DA-2 can be plugged in. These are marked in the diagram on this powerstream web page. So, one can in principle plug two Dell DA-2s into the socket to achieve a total of 400W power. In the following, I am dealing with only one. You can find the P4 connector's pin-out on this playtool page.

I started from the 24-pin ATX extension cable and removed all the pins from the male socket.

Call the two P4 extension cables P4-A and P4-B. I removed the male sockets on both of them, leaving the wires with only male pins attached at one end and connected to a female connector at the other end.

- I inserted P4-B wires into the ATX male socket, yellow wires at positions that correspond to Dell's pins 3-4, and black wires at positions corresponding to Dell's pins 7-8.

- I inserted P4-A wires to the ATX male socket at positions corresponding to Dell's 1-2 & 5-6, but with a few modifications. I removed the yellow wire at pin 1 entirely. (This would have gone to the 'reserve' line of Dell.) I removed the black wire at position 3 from the female end of the P4-A, even though I inserted the male pin into the ATX male socket. (This is getting connected to the 'remote' line of Dell.) To keep my colors clear, I actually replaced the black wire by a red wire from the ATX extension cable.

- I plugged in the P4-B's female plug into the PicoPSU's power input socket. The P4-A's female plug went into the motherboard's P4 socket. (Note that two circuits from Dell DA-2 are going into the Pico, providing a nominal 144W power, and one cirtuit is going into the motherboard/CPU, for a nominal 72W power.

Now, plug in the Dell DA-2 into the ATX socket and we are ready to go, except that the power brick is still on standy. We have to ground the 'remote' wire which is currently hanging. Where are we going to find a ground line? Remember that the PicoPSU has its own P4 connector, which we are not using. I shorted the 'remote' wire to the Pico's P4 ground line using a paper clip. The brick turned on and I tested to see if everything worked.

The paper clip is not a permanent solution of course. If one is willing to do some soldering, the 'remote' wire can be soldered to any ground line available. But is there a way to ground the 'remote' wire without soldering or crimping? Well, there is. Find an idle 20-pin ATX female plug. If you purchased an ATX extension cable for the male socket, then you have one lying around. Insert the 'remote' wire (currently terminated by a female ATX pin) into the position 14 and a ground wire into the position 15. (If it is a 24-pin plug, then adjust the position numbers accordingly.) Then plug this into the ATX PSU bridging tool. Voila!

I will post some pictures when I get a chance.

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Post by ryboto » Tue Oct 27, 2009 11:38 am

I'm curious what kind of voltage drop you're getting between the pico and the brick's PCB. I measured over .6v loss with my connector. What is your 12v reading in the BIOS or software monitoring?

reddyuday
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Post by reddyuday » Tue Oct 27, 2009 4:20 pm

ryboto wrote:What is your 12v reading in the BIOS or software monitoring?
The motherboard software is reporting 11.827V, which agrees with Speedfan. The BIOS says 11.774V during boot. It could be a reading from a different part of the motherboard.

The exact voltage readings at the end of the cables are as follows. End of DA-2 cable: 11.87, end of P4-A: 11.86, end of P4-B: 11.86. So the voltage drop in the connectors is negligible.

The only strange thing that I noticed after powering the machine up with the PicoPSU was that my monitor display had shrunk a bit in the horizontal direction. (I am using the motherboard's IGP. I use the GeForce for only programming.) Everything else seems completely normal.

Edit: Added current physical measurements of voltages.

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Post by ryboto » Fri Oct 30, 2009 7:46 am

What are the 12v voltages under load? Did you ever measure the 12v at the brick? I mean to say, did you open up the unit and measure the 12v from the PCB?

reddyuday
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Post by reddyuday » Fri Oct 30, 2009 5:05 pm

Hi Ryboto, Under Prime95 torture test, the voltage drops to 11.669-11.722V according to the motherboard software. It is back to 11.827V after the test is stopped.

I didn't measure the voltage at the power brick PCB.

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Post by yetidaddy » Fri Jul 16, 2010 7:39 pm

hi,
I'm really sorry to bring up an old topic but I tried to talk to engineer and my brother who knows how to solder and no one knows what I'm trying to do. I'm going to try the method like Atheara's post but I took some of his recommendations and ordered the mini-jr female-female. It been 3yrs for him, so he couldn't provide support and I was wondering if someone could in this thread.

viewtopic.php?t=38787

What I done so far is get 6 wires from my atx psu so I can make wires that connect to 2-4 and 6-8 on the dell-da-2. Pin 1 should have nothing in it as I recall in dell-da-2. And the "trigger" should be soldered to the ground with a 2-pin header? I'm trying to explain how to do this to my brother but I need someone to help me. Thanks. I will post pm pics if anyone want to see.


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