Thinkpads Forum

My T520 was seemingly incorrectly shipped with the 90W adapter, since it's a quad-core model with switchable graphics, it should've come with a 135W adapter, and throttles quite hard on the 90W. I've come into possession of a 170W adapter from a W520, however the end is keyed. If I cut away the extra plastic so it'd fit, would this model work with my T520? Or would the system not recognize the adapter and refuse to use it? Just wondering if anyone has any experience with this before I start hacking away at it and ruin the chance of possibly reselling the thing.

Speedboy wrote: ↑

Mon Sep 11, 2017 10:20 am

If I cut away the extra plastic so it'd fit, would this model work with my T520?

Yes.

Short and sweet. Don't suppose you have any idea whether it would recognise it as a proper 170W adapter and stop the throttling I'm getting with the 90W adapter?

Reckon so. I believe the resistance of the center pin is what is used for the "handshake" between the laptop and the adapter, and this is how the laptop "recognizes" the adapter.

Just a quick update to say I've done it, and it works fine. I just slowly and gently sliced away at the plastic with a razorblade until they were both gone. The laptop recognizes it as a 170W adapter and my throttling issue is gone.

Not entirely sure I'd suggest slicing up a power adapter like this, but if you're extremely careful to do it without damaging the rest of the plug it does work fine, so if you're in a pinch like I was, could be an option.

Speedboy wrote: ↑

Mon Sep 11, 2017 3:41 pm

Not entirely sure I'd suggest slicing up a power adapter like this, but if you're extremely careful to do it without damaging the rest of the plug it does work fine, so if you're in a pinch like I was, could be an option.

Don't worry. It's a standard mod that's been discussed here multiple times. Usually the suggestion was to file it off, not slice it off, IIRC, but the end result is the same. You are really just removing some excess bits of plastic, not messing with the actual wiring.

Glad it now works well for you.

If you want some figures: https://forums.lenovo.com/t5/ThinkPad-P ... 191#M43672

A razorblade? Seriously?

This 'keyed' problem can be fixed in like two seconds with a security-Torx screwdriver.

Haha, funny thing. Someone (not me) even quoted me into the Thinkwiki on this one;

http://www.thinkwiki.org/wiki/Power_Con ... her_Models

But OK, having a full set of Security Torx screwdrivers or bits might not be exactly commonplace.

It works just fine with the other models. Some older ones recognize it as a different Wattage than it actually is though. T61 sees it as '120W'; but who cares...

The same nonsense with the docks; at random they do or don't accept the 170W tip. Anyone has yet to explain me the difference between the "170W dock" and the "135W dock". Ripping out the useless plastic in the 170W is the easiest thing to do, and it also gives rotational freedom in the W520. I see no functional reason why Lenovo even created this problem.

As of May 2021 regarding the connector adaptation of the 170W supply, the security-Torx screwdriver trick worked for me too in modifying the connector. However, for those who may have difficulty to start it like me. Do this: Use one of those triangular scalpel-type knives // X-Acto Knife// to chip away at the ridges as much as possible. Then start with a smaller torx like T25 and gently bore away the plastic ( mind the center-pin, so as not to bend it) Move up in torx sizes as you progress until T30. My first ridge came off with T27 and the 2nd one with T30. It fit like a glove after that, Good Luck!

I just used the thin box cutter knives and just nibbled away at the two ridges until the plug went on to a T530 smoothly. I use the 170W ones in the mini docks and with the single W530. Most of the mini docks will take the plug without cutting the ridges away, but some older ones wont.