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Punch Card
Posts: 11
Registered: ‎04-14-2017
Location: PL
Views: 2,394
Message 1 of 3

Need information on wiring on power jack in Lenovo Y50

I need information about wiring of the power jack in Lenovo Y50. I mean wiring at the plug which is plugged into the motherboard from the power jack. Please refer to the attached photo. There are 5 wires (counting from left): 1 - blue, 2 - black, 3 - black, 4 - red, 5 - red. I need the following information:

1. What is the function of each wire (ground, power supply etc.) and required voltage on each wire once AC adapter is on?

2. Are 2 black wires (wires 2 and 3) internally connected? I checked with multimeter and among all pairs of all 5 wires, only those 2 wires are shorted? Is it correct?



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Posts: 4,286
Registered: ‎11-18-2012
Location: US
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Message 2 of 3

Re: Need information on wiring on power jack in Lenovo Y50

I'm not an owner of your model, but tracing the wires on the power port side should give you an indication of the wiring scheme.  Using an ohm meter the two red wires should connect to the center pin of the port.  That center pin would receive 20v DC from the charger adapter.   The two black wires should connect to the grounding contacts on the outside edge of the port.  As for the blue wire, I have no idea what the function of that would be and the ohm meter would give you an idea to which contacts inside the port it connects to.  I'm guessing that the blue wire is connected to the center pin of the charging port and that allows the laptop to monitor the input voltage directly. 


If the black wires on the power port are indeed grounds then the reading you are getting on the motherboard side of wiring harness would be correct as the black wires are both grounded and would show a shorted reading. 

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Punch Card
Posts: 11
Registered: ‎04-14-2017
Location: PL
Views: 2,365
Message 3 of 3

Re: Need information on wiring on power jack in Lenovo Y50

Thanks for the reply. As you said two black wires seems to be ground, red ones are supply with one red wire connected to the left inside wall of the jack with  20V, the other one connected to the right inside wall of the jack with 20V. The blue wire is the center prong and it doesn't carry any voltage but it's not ground either, though there is some finite resistance to the ground black wires. 


However, can someone from Lenovo confirm that's correct wiring interpretation, especially that two black wires 2 are indeed ground and thus are connected and what the blue wire  is for and whether it should be connected to the center prong. My Lenovo fried one of the transistor on the motherboard and burnt a hole in PCB making the motherboard useless and it happened just a few months after the warrant expired. Before I hook up the new motherboard I had to buy to the power supply, I want to be 100% sure that everything power-wise is sound.

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