I’m working on a Lenovo Thinkpad T400 , Type 7417ct0 with a power problem. The customer described the problem as Computer won't boot, works sometimes with charger and battery in. When battery is removed, still doesn't work. User needs an estimate.
Link to Hardware Maintenance Manual - ThinkPad T400 and R400http://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles_pdf/43y6629_04.pdf
The ac adapter tested ok. Outputs 20 VDC. I also swapped in a shop adapter ,20V 4.74A .same symptom. I measured the voltage at the mother board connecter. I read 20 VDC on the mother board side. So ,I think the DC in cable is ok. The DC in cable connecter on the motherboard is a five pin connector. Two black and two red and one Blue. I know that the black and red wires are the 20 VDC .I not sure what the blue wire is used for.Scott,Do you know what the blue wire is for ? I suspect it’s for battery sense or a data line of some kind. I suspect that this system has a bad mother board. The power icon does not light on when the ac adapter is inserted into the dc-in jack. Sparepartswarehouse wants Factory Direct $323.53 for the cheapest and Factory Direct $474.12 for the most expensive, and the FRU no. do not match the MM part list number,although these are the planar board listed for the IBM-Lenovo Thinkpad T400 (7417000). I still have to contact Lenovo for price and availability of the planar board.