One more for you guys, ATX power supply to bench unit mod

[ContraptionMaker]

03/22/2006: "ATX power supply to bench unit mod"

This project was inspired by this excellent wiki entry and Matthew Beckler's project found here
Before getting into this project I want to quote Matthew's warning....
Please Note! There are several large capacitors in ATX power supplies, that will store a dangerous charge for a long time. Please let your power supply discharge, completely unplugged from the wall outlet, for a few days before opening it up. You can probably be seriously hurt, so please be very careful.
That being said, on with the build...
"Part 1: Gathering parts and cleaning up"

I started with a power supply that I harvested from an old e-Machine. I liked this unit because of its size. My work space is limited so the smaller the better.

In addition to the PSU I will use the following parts in this mod.
5 way binding post (6)
LED assembly from Radio Shack (these have the resistor and LED holder as one unit and only cost a couple of bucks)
10 watt 10 ohm power resistor
Fuse holder
SPDT mini switch
And spare molex connector

When I opened up the power supply I could not believe how dirty this thing was!

A soft brush and a can of air were all that were required to get it cleaned up.

After cleaning the inside the next step is bundle like wires together.

After bundling the wires I removed the circuit board from the case so I could trim the excess wires and guess what I found, yep, more dirt.

Once I finished the cleaning I then counted the connections I needed and removed the unneeded wires.

Now it was time to layout and drill the holes in the front of the ps for the LED and the binding post. I would mount the fuse holder where the wires originally passed through the side.

The next step was to scan the front of the case. This would give the layout of my holes and help me place my labels. Once my design was complete I printed it out on a full sheet label and stuck it to the front. Using an Xato knife I cut the holes for the various components.

I cut the backing so it would keep the top from sticking. I had to keep this loose so I could put the screws back in before I sealed it down. Also note the on/off switch mounted on the back of the unit indicated by the red arrow.

In the next post we will install the binding post, LED and fuse, replace the circuit board and wire it all up.

[ContraptionMaker]

"Part 2: Wiring it all up…"

Ok…we’ve cleaned it up, drilled some holes in it, and gave it a new face. Now let’s give it some features and get it all juiced up!
The first thing to do is put in the binding post and slide in the circuit board and make sure everything fits. You may find, like I did, that you still need to do some modification to make it all fit.

When I slid the circuit board in I found that the ground post hit one of the riser boards. If I had drilled an 1/8” higher I would not have had this problem.

The solution was rather simple though. I simply notched the bottom of the post to fit over the board.

Notch in post.Post over riser board.

Once you have everything fitting it is time to route the wires to their connection point.

I’m not going to go into the wiring because it has been done so well already. Just follow this link
Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply

If you are really sharp you will have noticed that my second post is labeled -5v but I have the 5vsb hooked up to it and you would be right. After realizing that there was no -5v in this psu I decided to go ahead and make it hot all the time. This way I could quick test LED’s and such without having to turn on the power.

Ok, now that we know where everything is going its time to get out the soldering iron. After connecting the LED and splicing the brown and orange wires I started on the post. After a couple of tries I decided there had to be an easier way. Molex to the rescue! I pulled the individual connectors from a couple of old female plugs.

If you never taken these out the trick is the two little ears on each connector. The trick is to push these in a little so it can slide out. They make a tool for this but you can also use anything small enough to get to the bottom of the connector. A jewelers screwdriver works great and so does the tip of your X-acto knife. Gently pull on the wire while you are pushing each ear, one at a time, until the whole thing slip right out.

It turns out that, because of those "ears", these would actually “snap” on to the ends of the post. Instead of trying to unsolder the connector I just broke it off instead. I then stuck the wire in the end and soldered them together.

Before slipping on the connectors I slipped on a piece of shrink wrap. This is what it looked like after I got it all hooked up.

Next we will secure the power resistor and light this baby up!

[ContraptionMaker]

"Part 3: Power it up, light it up!"

Ok we are almost done...I wanted to give my supply a little pizzazz so splurged and spent $2.00 for a lighted fan guard and mounted it to the top of the unit. The original guard was your standard concentric circles.

Of course those had to go…

And here it is all together.

Now we will route the fan and light wires through one of the fan mounting holes and secure them with epoxy.

After making the splice I shrunk wrapped each and then one more piece to hold it all together.

Next step is to solder in the resistor. Also notice the red arrow in the pic. The mounting ear of the fan had to be cut off to keep it from hitting the switch.

Since this is a heat producer it needs to have some sort of heat sink to keep it from burning up. There was not room to wire it to the back so I came up with what I think is a better way. Thermal epoxy.

This is a two part epoxy with thermal properties. They carry two types, Artic Silver or Artic Alumina. The difference being of course a silver or aluminum base. I found this at my local “Computer Deli” but you can also order it online at ArticSilver.com
Here is a quote from their web site:

Characteristics:
Arctic Alumina Adhesive uses a layered
composite of aluminum oxide and boron nitride.

Arctic Alumina Adhesive is a pure electrical
insulator, neither electrically conductive nor capacitive.

A set of Arctic Alumina Thermal Adhesive
consists of two tubes containing a total of
5 grams of adhesive (2.5 grams each of parts
A and B) and a plastic reusable mixing wand. (Approximately 3cc total adhesive.)

Although lighter per set than Arctic Silver
Adhesive due to its use of ceramics rather than silver,
each set of Arctic Alumina Adhesive
contains the same amount of adhesive by
volume as a set of Arctic Silver adhesive
and will cover the same area.

CAUTION!
Arctic Alumina Thermal Adhesive is a permanent adhesive.
Any components you attach together with Arctic Alumina Thermal Adhesive will stay attached forever.


Here it is all glued up and ready to close the cover.

For the last step I added some old case feet I had laying around.

Here it is, the finished bench unit!

Here it is turned on.

Even looks good from the back!

Here are voltages I recorded

3 volts5 volts7 volts

12 volts17 volts24 volts
This is something I use almost daily and has served me very well over the last couple of years and I am sure will for many more.
Well that's it! I hope you have as much fun building your own bench unit as I did.

[Mach]

Nice work! +rep

[SXRguyinMA]

nice write up! I'm going to build my own now +rep

[widefault]

Like it. This is one of those things I've had planned forever, but never got to. Rather than bench power, mine will be used to get rid of the herd of wall warts and power bricks crawling around my power outlets.

[ContraptionMaker]

Just do it guys...it's easy and it's something I use almost every day! I use it to test lights, dvd's, even power an air pump that uses 4 D batteries. It's pretty fool proof too...if you accidentally short + to -, the psu just shuts down. Just turn it off then back on and everything is ok! Now get busy and show me what you can do! I know you guys got mad skills and will make something really sick!

[ContraptionMaker]

Thanks for the rating! It's nice to belong to a place where you are appreciated!