My ibm think pad t40 is not switching on - IBM Computers & Internet

Hi
Assume you are trying this on battery and mains?
1st thing is to check if the AC power adaptor is giving out any power, which you can do by obtaining a multimeter and setting it to 50 volts DC. Place the positive probe in the centre of the adaptor plug and the negative against the outside of the adaptor plug and see if you get a reading. this will confirm that there is power getting to the laptop

(NOTE: THIS IS TO BE TAKEN FROM THE DC END of the power adaptor NOT from where the kettle lead AC source enters the adaptor.. if in doubt, get someone who is competent with using a meter)

2nd, is to check that the power button is not sticking and that the small plastic pin between the laptop body and the screen ( I think these have one) is not stuck, preventing it booting

3rd, If you are getting power by AC to the laptop, check the condition of the DC jack socket, if it is loose, appears to spark whrn the jack is plugged in or crackles, this will need replacing

4th, If the above do not work, it is possible that the main fuse in the laptop has gone...specialist repairers job.