need help about smps adapter

I have an Hp smps adapter which was burnt. Its output rating is 18.5volt dc 3.5amp. 65watt. This is not available in my local market. But i have another smps adapter with same specification with two output + & - only. But in Hp SMPS adapter there is three wire (RTN, ID and Out which is written on adapter pcb).But I could not understand how these three RTN, ID and out manage with our local smps adapter.
Plz give suggestion so i can do my work properly.
With thanks.

sahu; What is this for? Did the old HP SMPS have three wires on the outputs and whare did thay go. The ID output may be a remote sense wire or maybe even chassis ground. Andy

4pyros said:

sahu; What is this for? Did the old HP SMPS have three wires on the outputs and whare did thay go. The ID output may be a remote sense wire or maybe even chassis ground. Andy

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as u say .then what s postive and nigetive.