W520 requires 170W AC adapter

[hellosailor]

If you mean the correct able with the drop-down resistor in the end fitting?

AFAIK that's only sold integral to the power supply. It does not unplug. So unless there's some oddball source for these, you'd have to buy a standard plug and add the resistor yourself. Or lop one off of an older power supply that wasn't working.

One day my computer surprised me with a "wrong power supply" message. It turned out that the plug had just worked out of the socket, just a little bit. And despite the message, the computer kept working just fine.

[KMantas]

I wish I knew about this issue before and haven't thrown away old cable :/ where is that resistor? is it in the plug or in that thicker part which is ~20 centimeters before the plug?

[hellosailor]

I can't swear how Lenono does it, but the resistor is usually installed "in" the plug, or at the point where the cord enters it.

USB devices all use the same logic, with a drop-down resistor added into the plug to signal different types of cables. And resistor values chosen by the device maker, not set on any universal standard.

[axur-delmeria]

It's soldered to the terminals of the plug before the rubber sheath is molded.

It's not hard remove the sheath and solder the resistor-- the big problem is how to put the sheath back on.

If the plug itself doesn't heat up much, it may be possible to use hot-melt glue to make a new sheath. I've done something similar, but it was a 3.5mm stereo headphone plug, not a 135/170w power connector.

You might have to research DIY silicone rubber injection molding techniques.

[KMantas]

thanks for replies

I'm thinking what would happen if I just connect outer shell with center pin.
In the chart I see
0 Ω = 135 W barrel

so maybe it will that it is 135W charger and it is going to work?

[KMantas]

got it working - put some resistor. but I think it should work without it also. Will try next time if it breaks again

[jcvjcvjcvjcv]

thanks for replies

I'm thinking what would happen if I just connect outer shell with center pin.
In the chart I see
0 Ω = 135 W barrel

so maybe it will that it is 135W charger and it is going to work?

I believe you can do that mod inside the Thinkpad.

[axur-delmeria]

I believe you can do that mod inside the Thinkpad.

Isn't this dangerous, disconnecting the center hole on the DC jack, then soldering a resistor and connecting it to ground?
Now it won't be able to detect the actual wattage of the adapter. :O

[jdrou]

I believe you can do that mod inside the Thinkpad.

Isn't this dangerous, disconnecting the center hole on the DC jack, then soldering a resistor and connecting it to ground?
Now it won't be able to detect the actual wattage of the adapter. :O

That depends on what the consequences are of getting too little current from the adapter. Most likely either the laptop won't run, will run at lower power state, or will drain the battery (if the adapter is current-limited) OR the adapter will overheat and shut down. None of those should cause physical damage AFAIK. A no-name adapter from China could certainly be a problem though so I wouldn't use one of those with such a mod (if at all).

[jcvjcvjcvjcv]

I believe you can do that mod inside the Thinkpad.

Isn't this dangerous, disconnecting the center hole on the DC jack, then soldering a resistor and connecting it to ground?
Now it won't be able to detect the actual wattage of the adapter. :O

Just a direct connection between center hole and ground if I remember right. That should make the laptop think a 135W PSU is connected whenever a PSU is connected.

Let's face it: W520 does not support that super fast charging. With light use you are never crossing that 90W, even when charging.

That 170W is designed around

The 170W requirement is for a fully populated and utilized W520 with the 2000M GPU, the i7-2920XM processor running flat out at 3.5GHZ TurboBoost, all controls at maximum performance, 16GB RAM, all USB and eSataP ports utilized. The power demands in that scenario will exceed 135W, hence the need for the 170W supply.

https://forums.lenovo.com/t5/W-Series-T ... m-p/556067

+dock I guess.