1. Computer problem? Tech Support Guy is completely free -- paid for by advertisers and donations. Click here to join today! If you're new to Tech Support Guy, we highly recommend that you visit our Guide for New Members.

Using Computer Power Supply for 12v Power

Discussion in 'Hardware' started by golfmjc, Dec 19, 2004.

Thread Status:
Not open for further replies.
  1. golfmjc

    golfmjc Thread Starter

    Dec 19, 2004
    I have a Delta DPS-150GB B Power Supply out of an Apple Macintosh Power Mac computer. I would like to use it as a 12v/5A power supply for my model train layout. I have a couple important questions:

    1) I need to know the pin-outs of the connectors (1-4pin, 1-14pin, 1-5pin on ribbon wire), specifically which ones control start-up and various voltage outputs.

    2) Being a Switching Power Supply, I think there must be a load on at least one of the output rails. Can I create this with a simple resistor of some sort? if so, how exactly what would I need to do.

    I can email photo of the connectors if that would halp. I would appreciate any help. Thanks.
  2. Cosmic


    May 5, 2003
    Here is your typical ATX Power Supply Connections Pinouts

    1 +3.3v
    2 +3.3v
    3 Ground
    4 +5v
    5 Ground
    6 +5v
    7 Ground
    8 Power_Good
    9 5v_Standby
    10 +12v
    11 +3.3v
    12 -12v
    13 Ground
    14 Pwr_On
    15 Ground
    16 Ground
    17 Ground
    18 -5v
    19 +5v
    20 +5v

    The best way to really know is just take the cover off and check the PC board to verify the pins are as above, they should be marked. I know nothing about that exact power supply.

    You must also know how the power supply is switched on. Did it use a front panel switch in the PC. Best to actually figure it out while still in the PC.

    +12 Volts is used mostly for fans and drive motors. Here is a pretty standard connector for disk drives pinout and wire colors.

    1 Yellow +12v
    2 Black Ground
    3 Black Ground
    4 Red +5v

    You must have a load on both the +5V and +12Volt.

    If it is a cheap PS, you can destroy it but operating with no load. The top shelf type power supplies will have a built in load resistor, so that they can run even though no normal load is plugged in. More standard is power supplies have a minimum load requirement for both the +5v and +12v sides, and if you fail to meet this minimum load, the supply shuts down.

    You probably need something in the range of 2 to 3 amps minimum load on the +5V and maybe .5 to 1 amps on the +12 V

    You need to know something about the load your train set will draw. Can you just put a basic load on it with a load resistor and then switch On / Off the train set and still be within the rated output or must you plan on rigging up the switch so it also switches the dummy load in / out as the train is started / stopped.

    One good form of dummy load can be extra fans or lights or something where you know the rating and maybe can use as well in a continuous mode. Or you can just compute a load resistor. Be sure to be very conservative on the wattage rating.
  3. golfmjc

    golfmjc Thread Starter

    Dec 19, 2004

    Thanks for getting back to me. I really appreciate your help and expertise.

    This power supply came from what was at the time probably a pretty expensive Apple Macintosh, so I would guess it is a good quality PS. Macintosh's turn on via a keystroke combination - no on/off switch anywhere! That would be too easy...

    Unfortunately, the connectors do not match what you describe as a normal ATX configuration.

    The larger of the three connectors is a 14pin, not 20pin connector here are the colors of the wires going into it. I'm not sure whether pin 8 is across from 1 or across from 7 so I've shown what color wires are directly across from each other.

    1-Red - Red
    2-Black - Red
    3-Black - Black
    4-Orange - Black
    5-Red - Orange
    6-Black - Blue
    7-Black - Blue

    The four red wires coming from an area marked +5V on the PC Board inside the PS. There are two Orange wires coming from an area marked +3.3V. I can't see down to where the two blue wires come from - I'm assuming they are the 12V output. The six Black wires, of course, all come from an area marked GND.

    There is a 4pin connector which has 1 Blue, 1 Red and 2 black wires. We can probably assume that the Blue is the equivalent to Yellow +12v you mention.

    Both of these connectors are female.

    There is also a 10 pin male connector attached to the end of a 6-conductor ribbon cable. I have no idea what this does and can't see any identification for the plug on the PC board that it goes into.

    I know very little about electronic circuitry, so can't be much help on what my trains draw, except that I have a small transformer rated 7VA and it will not power my large engines sufficiently. I bought a 3A/60VA transformer and with that everything works beautifully.

    I was hoping to use this freebie Power Supply I found, which says it's rated 5A at +12v, as a supplimental or auxilary power source for my trains. Perhaps there is more to it than I am capable of handling. If you don't mind holding my hand, I'm willing to continue trying, however.

  4. Cosmic


    May 5, 2003
    Macintosh's turn on via a keystroke combination - no on/off switch anywhere! That would be too easy...

    Not good, probably difficult how to figure exactly what to do to duplicate the turn on. I just about need to see and play with the hardware as a working computer.

    A better choice is maybe this. You know somebody has already done just about everything. Read thru this. Explains the more common power supplies. The ones from the old AT towers with the paddle switches are nice for the purpose.


    I have lots of these laying around. You can have a couple free if you pay the freight. Maybe after Xmas. Am a bit busy right now. I probably have the complete lash up including the On / Off switch, cables, power supplies. Some might even be from old XT types. Know I have a couple old IBM original Power supplies. IIRC, those came with a dummy load built in.

    The one thing you must be extremely careful, you can get in direct contact with 115 VAC and must know exactly where not to be touching, 115 VAC can kill you under the right conditions.

    Am redoing the basement floor right now and my work benches are piled high with junk. So will be a week or so, till I can have a look.
  5. golfmjc

    golfmjc Thread Starter

    Dec 19, 2004
    That all sounds very logical. Trying to use the "thing" I have sounds like more trouble than it's worth. The article you sent was interesting. I'll try scrounging around here to see if I can get another freebee or two. If not, I may take you up on the offer.
    Thanks for your help.
    Merry Christmas!
  6. LT.Maddog420


    Jan 26, 2006
    I have a Delta DPS-150GB A Power Supply out of an Apple Macintosh Power Mac computer.
    you have the Delta DPS-150GB B so this may help you
    i have 5 connector in all
    3x 4 pin (1 Blue +12v) (2 Black Ground) (3 Black Ground) (4 Red +5v)
    1x 10 pin (1 to 4 Black Ground) (5 White -S) (6 to 9 Orange +12v) (10 Brown +S)
    1x 22 pin (1 to 4 Red +5v) (5 to 9 Black Ground) (10 N/A) (11 Gray -12v)
    (12 Yellow TRKL) (13 to 16 Red +5v) (17 to 20 Black Ground) (21 Purple /PFW)

    Now on the 10 pin connector jump pin's (5 White -S) with any of (1 to 4 Black Ground)
    now jump pin's (10 Brown +S) with any of (6 to 9 Orange +12v)
    That will tell it all is good :p
    Now on the 22 pin connector jump pin's
    (12 Yellow +5v TRKL 0.1A MAX) with (21Purple /PFW)
    This is your on and off for it NOTE: The 10 pin connector (6 to 9 Orange +12v) DO NOT have the D303/Diode in line with them like the (Blue +12v) do.
    so using the (6 to 9 Orange +12v) for your +12v on Fan/HDD/CD/etc/etc
    may Damage it
  7. Sponsor

As Seen On
As Seen On...

Welcome to Tech Support Guy!

Are you looking for the solution to your computer problem? Join our site today to ask your question. This site is completely free -- paid for by advertisers and donations.

If you're not already familiar with forums, watch our Welcome Guide to get started.

Join over 733,556 other people just like you!

Thread Status:
Not open for further replies.

Short URL to this thread: https://techguy.org/309592

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice