HP Laptop 3 wire vs. 2 wire problem


Old 12-11-10, 03:53 PM
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HP Laptop Power Supply 3 wire vs. 2 wire problem

The power supply on my HP dv6 laptop died. It provided 18.5V DC at 3.5 amps.

I have a working power supply from an older HP laptop that also delivers 18.5V DC at 3.5 amps. I want to use the older power supply with the new laptop.

Here is the problem...

The older power supply has just two wires. 18.5V and ground. The newer laptop (with the busted power supply) has three wires.. all coaxial.

I removed the plug from the newer three wire (broken) power supply with the intention of soldering it onto the wires from older, working power supply with only two wires.

What is the third wire? What do I do with it?

How do I get my laptop, which expects three wires from the power supply, to work with just 18.5V and ground from the old power supply?

Any help would be appreciated.

Last edited by Sped2001; 12-11-10 at 04:46 PM.
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Old 12-12-10, 10:24 AM
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It turns out the outer shield is ground, the inner shield is +18.5V DC, and the center conductor is for some sort of data communication between the laptop and the power supply.

I ditched the idea of using the old 2 wire power supply with the 3 wire plug when I discovered the problem was not the power supply, but the connection between the 3 wire cable and the plug that goes to the laptop.

It was very poorly constructed, and the +18.5V and ground were shorted. At least the power supply and laptop were robust enough to survive the short.

I fixed the short in the three conductor plug and now all is well.

Oh, and HP is sending a new power supply under warranty to boot.
Old 12-12-10, 11:53 AM
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Glad you got it figured out.

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