I am working on installing a laptop connected to a touchscreen in my car. I bought this Opus DC-DC supply (model DCA9.180) to power them both:

I got the touch screen (Lilliput 669) from the store here:

and the laptop is a Dell Latitude D600 I purchased in a used equipment sale at work. It came with a port replicator / dock that I'm planning to use for the install, so I can hardwire it in the car and have the ability to eject the laptop if I ever want to use it outside the car. It is a D/APR model number PR01X.

The V1 and V2 outputs on the Opus are straightforward enough, but I need a sanity check for using the power switch output. I took apart the dock and did some probing with my multimeter.

The switch board has two buttons on it, one for on/off and one for doing a "hot eject". The on/off button is labeled SW2 on the circuit board, and has these numbers printed around its solder points (the 0 in the middle is the button itself):

1 2
3 4

Next I looked at the wire bunch going to the switch board. There are 8 wires, and the first 4 are colored like this:

1 - black
2 - brown
3 - red
4 - orange

With the A/C power brick attached I took a guess that the 1 / black was negative and I found a constant 5v on 3 / red. I pressed the SW2 button and nothing happened. Next I tested the 2 / brown as negative and 4 / orange as positive. I got the same initial results, but when I pressed the SW2 button the 5v on 4 / orange went to 0v.

Is it safe to assume the brown and orange pair are what I will connect the power switch output from the Opus to? Is there any other testing I should do before wiring it all up?

If you have any questions or comments about my proposed setup I would be glad to hear them. Thanks for reading!

- Justin