Polarity on adapter

[Psenica]

Hello,

how can i know pollarity of cables on HP adapter?

on that ending overhead...there is + in the middle and - around...like on scheme on adapter

on HP adapter is same schceme

but in hp adapter..there are 3 cables...white,black and blue...i dont know for what is third but i want to know which one is + and which one is -

sorry for my english and thanks for answer

[banhien]

Hi,

Please check the following guide:

   http://www.instructables.com/id/Repair-your-broken-Laptop-power-cord/?ALLSTEPS

Regards.

[Psenica]

nah...

it is not i am looking for...

i still dont know pollarity...look at picture i posted... i dont know which cables i must connect together....i need + and +

- adn - ...if i connect + and - ...its end for my laptop

i know that on ending i have jsut 2 cables + in middle and - around but on that HP adapter there are 3 cables and i dont know which is + and which - ...this it hp adapter i have http://www.amazon.com/HP-Compaq-Adapter-4-74A-PPP012L-E/dp/B001VCRB94

[banhien]

Hi,

You have NOT read the whole article.

Regards.

[Psenica]

I read it again and i cant find it. Maybe becosue of my english. I just didnt find nothing about pollarity...and still he had just 2 cables...i saw somoen asking about blue cable in comments...but with no answer. So can you tell me how can i connect it? 

White with white,black with that one around wihte and blue with  nothing or how?