I'm planing to solder my own cable extension for the VRM (aka DC-DC card), as I want thicker wires than IDC Type cable solution provides. I want only use one (or few) wires per per voltage.

I found the pinout of the VRM in this forum, the number of pins used per voltage could be used as an estimate of the max provided current.

Now the question. Does anyone knows the maximum current per voltage the VRM can supply (and the max input current at 28V)? I would feel more comfortable if I could base the design on hard facts than on estimates.

Thanks
EBUC

Where exactly? Can't seem to find it with forum search :shades

here you go:

search for "pinout", all dates, view results as posts... and you'll find:

Topic: What about the 9000? Does it fit or not? (Pages 1 2 3 ...13 )

TomD
Forum: Cube Hardware Support    Posted on: Jan 15 2003, 12:42 AM    Post Preview: #5526

http://www.cubeowner.com/forums//index.php...t=30&#entry5526

Apple Cube DC-DC card pinout
Power Connector
A01 28V B01 28V
A02 gnd B02 28V
A03 gnd B03 gnd
A04 3.3V B04 3.3V
A05 3.3V B05 3.3V
A06 3.3V B06 3.3V
A07 3.3V B07 gnd
A08 gnd B08 gnd
A09 gnd B09 gnd
A10 gnd B10 gnd
A11 gnd B11 5V
A12 5V B12 5V
A13 5V B13 5V
A14 gnd B14 gnd
A15 12V B15 ENABLE

J2 HDD,DVD 1-dot 5v 2,3-GND 4-12v

Now that's a good hint. I've already found the "Any date" pulldown, but I've looked over that one. Makes search results much more responsive, especially if the desired post is hidden within such a monster of a topic.

Thank you very much, Laurie!

cu Armin

I finaly made the cable with few but thik wires. The cable works fine.

I used
- 2.5mm^2 +1.5m^2 for GND
- 2.5mm^2 for 3.3V
- 1.5mm^2 for 5V and 28V
- 0.75mm^2 for 12V and Enable
so I have everywhere at least three times the diameter of the IDC Type cable (that has a little less than 0.1mm^2 per wire).

I used two cables for GND instead of one 4mm^2, as this diameter could have given some problems when inserting the cube in the shell.

The only other thing to say is that it is a lot of soldering

I also attach a picture but as I already have sealed the connectors with silicon there is not so much to see.

Well, if you figure 100W for the CPU (not that it ever pull this much power),
that's 20A at 5V, rember also, the Cube speakers are supposed to be
20W and run off the USB 5V supply from the DCDC.

The 3.3V supply runs the vidcard, RAM and logic, that might take 30W or so,
so 10A @3.3V

The 12V supply on the cube is probably only good for 2-3A tops, it only runs
the hard drive and firewire. But still that's somewhere between 24W and 36W..

Now if you add all this up, you are way over the 225W (28V @8.125A)
of the cube power supply considering it is also supposed to supply up to 4Amps
at 28V for the ADC display. (112W) Only the ADC 17"CRT draws over 100W, the
max draw on the LCD is more like 75W.

So the max the DCDC board could pull off the 28V supply is about 4-6Amps (115-165W)
by design.. You size conductors by current , so the heaviest should be the 5V and GND
return since they could take up to 20A, this is 5X the load on the 28V line. Although I dont
think the parts on the DCDC board could do more than about 12-15A without blowing up.

So I think you may have undersized your 5V line relative to the others, but if you look up
the voltage drop (V=i^2 * R / cm) of the wire you used, you're probably OK, but still, you may want to
run a supplemental 5V line from the DC card directly to the 5V supply rail on the CPU card.
Powerlogix did this for their Duals that went into towers as a retrofit, apparently the
conductors internal to the motherboard weren't big enough to carry all the extra current
an upgraded CPU required. That may be the case on the Cube also. If you have a sensitive
voltmeter and can tack solder some sense leads to a 5V and GND point on the CPU board,
you can monitor the CPU 5V power while the cube is running some processor intensive task
like ripping and playing a CD with visuals on to your 17"CRT from a bus powered USB CD-drive.

Finally I found the time to open the Cube and have another look at the DC-DC board. I took the pinout contributed by TomD and transferred it in a more picturesque form :happy. It's the view on the DC-DC board's connector with the plug holes facing towards you. A1 is in the top left corner of the drawing.

A1_______connector_______
| 2 0 0 3 3 3 3 0 0 0 0 5 5 0 1 |
| 2 2 0 3 3 3 0 0 0 0 5 5 5 0 e | B15
================PCB================...

Legend:
0: GND; 2 x 2.5mm^2 (AWG14)
1: 12V; 1.5mm^2 (AWG16)
2: 28V; 2.5mm^2 (AWG16)
3: 3.3V; 2.5mm^2 (AWG16)
5: 5V; 2.5mm^2 (AWG16)
e: enable; 0.75mm^2 (AWG18)

All the pins with the same number will be soldered together and have a single wire conected to them, so I'll end up with 7 rather thick wires.

EBUC, could you please verify if above drawing is correct and matches your wiring? I'd like to give it a try and want to make sure I got everything right before (hopefully not) blowing my Cube :shades.

Armin

It looks good. But I don't want the responsibility if anything goes wrong. You can easy verify that yourself. The A1, A15,B1,B15 are printed on the PCB. Also you can see on the PCB how the pins are grouped (except the 28V).

Understandable.


That's what the drawing above is based upon. I just wanted a second opinion here, for the sake of it. You know, four eyes see more than two.


Good idea. Haven't looked on the back yet, but I'll do...
Wish me luck,

Armin

You can see it on the PCB of the DC/DC-card, you do not need to look on the back of the mainboard.

Well, ahem... I'd love to contribute intelligently to this very technical thread, but I just used a modified IDE cable when I moved the VRM. I've been using it for almost a year now (24/7) and I've never even had so much as a kernel panic that I can recall. I'm wondering why all the fuss over cabling thickness and voltage?

I think of myself as a shade-tree modder, not hardcore, but willing to spend some time and $ to do it right. Did I do it wrong? They say nothing succeeds like success.

My Cube Specs, Gigadesigns 1.2 GHz (7455), ATI Radeon 9000 64MB (hard-mounted not loose), VRM rewire, Panaflow fan, 4X DVD-R/RW/RAM, other easy stuff (RAM, HD, OS, Airport), 20" Cinema Display on ADC port, iSub, LaCie Pioneer 105 ext., various USB and other FireWire devices.

Matthew

It's likely that you, I and probably dozens of others that used the ribbon cable approach "got away with it" due to the power tolerances of the components in our individual systems.

I agree that the ribbon wiring (28 AWG?) is undersized, especially at the 9 - 12" length, for the theoretical worst-case maximum power requirements, but our systems either never see the corner-case, or we have tolerant components.

In short, I wouldn't sweat it.

Does anyone know the gauge of the ribbon PL use for their VRM relocation on the ClearCube. As far as I know, no-one has had issues with that?

doc

i have one of the PL relocation cables (no clearcube though), and it seems to simply be standard IDE ribbon cable. Its just short - between 5" and 6."

It had no issues running my PL 1.4, 1GB ram, and radeon 9000.

Since I'm a wee bit new at the whole electrical thing, is it possible to bypass the VRM altogether, and simply run the Cube off of a standard ATX supply. I imagine it's possible, but I'm at a bit of a loss as to how to make it work. Could anyone help?