Lenovo 3000 no power after replacing the keyboard controller chip

[goodbrethen]

I have lenovo 3000 with m/b part#: la-3451p, this laptop is working only with battery and not working on ac adapter i replaced the charging ic part# MB39A126 but still ac adapter not working after checking some components i saw keyboard controller chip part# ene kb295 it was burnt, then i replace that ic but after replacing when i try to power on again the laptop now its not powering on, even in battery now its no power. can somebody help me what to do next? help is very much appreaciated! thank you.

[lord]

Re: Lenovo 3000 no power after replacing the keyboard controller chip

maybe the ene that you put in is dead

[goodbrethen]

Re: Lenovo 3000 no power after replacing the keyboard controller chip

maybe the ene that you put in is dead

Maybe possible, but i bought it new, sealed with an anti static plastic. but i will try to replace it again. thanks for the help!

[lord]

Re: Lenovo 3000 no power after replacing the keyboard controller chip

Hope i helped!

[ben7]

Re: Lenovo 3000 no power after replacing the keyboard controller chip

Make sure there were no soldering shorts!

Try measuring the resistance across the DC jack, there might be some short somewhere else on the motherboard...

[heavymachines]

Re: Lenovo 3000 no power after replacing the keyboard controller chip

and check all 8 pin power mosfets for shorts where power comes in from dc jack thus could have shorted the ic you replaced......

[goodbrethen]

Re: Lenovo 3000 no power after replacing the keyboard controller chip

i tried to measure the voltage on mosfet lm393 pin5 beacause it was connected to B+ and resistor PR18 but its 0V but on transistor PQ1 which connected also to B+ the voltage is there. here i attached the scheme. i hope somebody can help me! thanks

[lord]

Re: Lenovo 3000 no power after replacing the keyboard controller chip

The LM393 is often an issue. You have this chips on most motherboards. Try to replace.