Lenovo Yoga 720 13IKB - doesn't turn on

[KHOR3S]

Hello!

I've recently bought cheap Lenovo Yoga 720-13IKB with possible RAM problems. The laptop worked but when it filled about 20-25% RAM (out of 16GB) the system shut down with an error (BSOD). Before buying new motherboard I've thought I'd try to reflow the RAM because it worked strange..

For example MemTest only showed errors, it couldn't boot from USB (except Linux Mint) but it booted to Windows normally after installing it on a different PC, etc.

I did the reflow on the RAM at about 215°C for few seconds on IR light reflow station. After that the laptop turns on for 2 seconds, the power light and backlight, then shuts down and restarts. When Charger and battery are present, the charging light blinks 3 times.

I've tried disconnecting everything from the motherboard and just plug in the charger but no luck.

Could it be I've shorted the RAM or fried the chip - or something else?

Thanks!

[mcplslg123]

Re: Lenovo Yoga 720 13IKB - doesn't turn on

Definitely ram chips damaged by reflow. Lenovo has glue underside bga. So temp shouldn't be that high. You should have gone to max 150-160 but for longer duration of say 5 mins. That would have not damaged the chips atleast.

[KHOR3S]

Re: Lenovo Yoga 720 13IKB - doesn't turn on

Definitely ram chips damaged by reflow. Lenovo has glue underside bga. So temp shouldn't be that high. You should have gone to max 150-160 but for longer duration of say 5 mins. That would have not damaged the chips atleast.

Thanks!

Could a fried chip or short cause other problems on the motherboard?


________________________________________________________

Just for advice:
Would it be better to spend 250$ on repairing the MBO (buying new chips and replacing them) or to spend 200$ for a new motherboard - because I don't know what are the chances of successful repair.

The one that I have is i7-7500U / 16GB RAM
New one would be i5-7*** / 8GB RAM

I bought it for ~150$
The i7 one could sell for ~750$
The i5 one for 450-500$

[reformatt]

Re: Lenovo Yoga 720 13IKB - doesn't turn on

Did they have underfill? Seeing this a lot in MAC's now, but wasn't aware that PC vendors were doing it. You can't float an underfilled BGA IC, you'll just end up with shorts between balls that way.

[Saihah Fakhriyah]

Re: Lenovo Yoga 720 13IKB - doesn't turn on

change the ram chips and check out