Using a 19V AC Adapter with a 20V Thinkpad

[pierre04]

Hi all,

My X60 AC adapter died recently. It was a 65W 20V PSU.

I have a 90W 19V spare adapter (from a packard bell laptop) and I am thinking of modding it to use with the thinkpad.
The 19V adapter delivers 19,4V without load.

My guess is there is some tolerence margin for the input voltage, and that the thinkpad sould work.
At worse I believe that it will not damage the motherboard, and just not boot, or randomly crash when drawing lots of power.

Has anyone tried a similar thing ?

[Cigarguy]

I guess it could work but why bother? Around where I live a genuine Lenovo power adapter can be had for around $10 in the local classifieds. You are taking a gamble. On the remote chance it does something nasty like trip a fuse or take out the MB, it could be expensive.

[rkawakami]

Has anyone tried a similar thing ?

Yes, somebody has thought of this before. To wire up the 20V plug correctly and get some background on this matter, refer to the following threads:

http://forum.thinkpads.com/viewtopic.php?f=18&t=78862 (Replacement 20 V DC cable from adapter to laptop?)
http://forum.thinkpads.com/viewtopic.php?f=30&t=92127 (What is the "signal" pin on the power supply cable for?)
http://forum.thinkpads.com/viewtopic.ph ... 4&start=90 (W520 requires 170W AC adapter; info on the 'signal' pin)

The short version: Make sure the polarity is correct (outer shell is NEGATIVE, inner barrel is POSITIVE) and the signal pin is connected to NOTHING.

And to be clear, I'd only do this in an emergency. As Cigarguy said, you should be able to find a genuine (used) Thinkpad adapter for fairly cheap.

[pierre04]

Here in France, a used genuine adapter is found at $30 and a brand new will cost more than $50. That's a bit expensive for a computer I bought for $120.

Anyway, someone pointed me a thinkwiki link that states it would work : http://www.thinkwiki.org/wiki/Using_16V ... _V_laptops

[rkawakami]

While wikis in general are a fairly good reference, I do not believe everything that's published in those places. A general rule of thumb is that most electronics are spec'ed at +/- 10% voltage tolerances. That means you could probably get away with 18V in place of 20V. 16V, when 20V is required, is a 20% drop. I would not try it with any one of my systems unless I had another one to replace it if something went wrong.

[pierre04]

Thank you for your helpful links and wise advices.