X40 Voltage regulator tolerance levels

[seneca]

Hello everybody

Has anyone opened up an x40 and checked what voltage regulator it uses? And what tolerance levels it has?

The default input voltage from the powerbrick is 16 volts. I know for a fact that it can handle a higher voltage. Once I accidentally used a compaq adapter that delivers 18V and it worked just fine.

But conversions from lower voltage to higher is usually more inefficient then vice-versa and generates alot of heat in the process.

I was thinking about using pure 12V (a car battery is usually around 13V though) directly into the X40, but that is a 25% reduction of input voltage and I'm not sure the lappy would handle it.

And btw, can someone give me an url to a X40 service manual. I'm thinking about opening it up.

[seneca]

Come on...

The thought of connecting directly to 12V must've crossed someone's mind before me?

[jdhurst]

The thought has occurred to lots of people in here. A voltage regulator can reduce voltage but not create it. 12 volts is too low (for me) as it is 25 percent below recommended. I do not try to run my refridgerator at 90 volts, either.

Most of us in here who value our laptops recommend the car adapter (special brick) or a DC -> AC 120 volt converter. I use the latter because it powers other things as well.
... JD Hurst

[seneca]

Yeah, guess 25% might be too much... But I think I just might open her up and get the name of the curcuit and check it out.

Do you have a link to a service manual?

[jdhurst]

That stuff is all on one board (motherboard). The basic regulation is done in the power brick. The motherboard is a multilayer board and the components generall have their leads underneath the components and are right difficult to get at. Knowing the name of the regular probably won't help (I could easily be wrong) because the basic input remains too low.

You can go to the Lenovo support site, key in your model number and then you should be able to find the hardware maintenance manual.
... JD Hurst