07-16-2019 12:42 PM
My Yoga 500 suddenly wont stay on, it turns of after 1-3 second. After maby 15 attempts it will boot untill shut down. I also noticed the battery is charging in similar 1-3 second intervals with the power light flickering in time with it. It runs on battery but on mains it has the problem. Help?
07-16-2019 02:09 PM
07-16-2019 03:27 PM
I have two working chargers, and spare power plug from another working unit. It seemes to be a board level issue? Like a mosfet or cap? Any one have the power rail schematics for this board I have a re ball station but where to start?
07-17-2019 08:50 AM
OEM schematics are internal documents so it would be a challenge to get one. Perhaps you should consider checking with your trusted schematics provider if they would have one available so you may start voltmeter testing specially if there is no visible physical issue observed.
07-17-2019 01:49 PM
Thanks for the reply, who would be my trusted schematics provider? I cant find any on google search. Im wondering if the start up chip may be to blame, keeping a mosfet gate shut?
07-17-2019 02:43 PM
OEM schematics are internal documents and I was thinking you have your source knowing you have your reballing machine. I am not confident that authorized Lenovo service center would provide such as they simply replace the motherboard if the dc in port is not the fault.
If you have fellow board level technicians, perhaps they may assist else Service Centers. Hard to guess with the risk with power related issue specially without certified schematics.
08-22-2019 04:19 PM
After alot of testing and research I am confident that the issue is caused by a falty micro controller - a nasty little Nuvoton NPC series chip, which needs programing befor installing. So without Lenovo's chip programing software this particular fault can't be fixed. Thats the problem with always on power from an non removable internal battery.