What's the difference between the 3 and 2 pin adapters?

[Rofflesaurrr]

I got a 90 watt 2-pin AC adapter for my T61p. A lot of sellers are also showing a similar one for the T61, but with a 3-pin AC cord. What's the difference? Does having the ground prong help cut down on noise or anything? It's FRU: 93P5026, which is what the service manual lists for my machine. There's a 3-pin listed as optional.

[bill bolton]

What's the difference?

Two pin mains cord connector ThinkPad power supplies are generally homologated for North America and one or two other markets. Three pin mains cord connector ThinkPad power supplies are generally homologated for everywhere else in the world.

There is no significant difference in the technical specifications for 2 or 3 pin connectors between each model of power supply, for most individual use purposes.

Cheers,

Bill B.

[RRHODY]

I was under the impression the three post cord had the single round pin as ground and the two pin cord was polarized for ground [Earth?].
Isn't that aq significant difference?

[EOMtp]

Isn't that aq significant difference?

No difference -- significant or otherwise! These switching power supplies have a totally isolated secondary (output) from the primary (input). Grounded or "floating" AC on the primary side makes absolutely no difference to the secondary DC output side of the device.

It isn't that there is very little difference between the 2-pin and 3-pin plug power adapters -- it's that there is no difference whatsoever, aside from the mechanical.

[RRHODY]

OK, it sounds plausible to this layman.

[Eudoxus]

But if there is no real difference then what's the point of making two different kinds of adapters?

[EOMtp]

But if there is no real difference then what's the point of making two different kinds of adapters?

Regulatory compliance with local jurisdictions.