Fujitsu S752 instant power off

[Snooples]

Hi All

Hope someone can help me with this laptop. I've not had much experience repairing laptops other than replacing bits for friends and family etc but I'm really interested in learning more component level repair.

I have a Fujitsu LifeBook s752 non-VPro laptop I was given to look at but i'm at a loss here. The laptop power lights up when plugged in, when you press the power button the blue power LED comes on only for an instant and then goes out. It then repeats that on/off indefinitely.

I've tried checking some voltages around the board and it seems like it is resetting everytime the power led goes out. The board has no silkscreening and I can't find a board schematic anywhere for this laptop.

Since it was basically scrap anyway I thought I'd try and puzzle out what might be happening as a learning experience, what I've learned so far is that fujitsu really don't want people repairing these laptops.

Has anyone seen anything similar, any ideas of what I could try to narrow down the issue?

Any guidance is greatly appreciated.

[Snooples]

Re: Fujitsu S752 instant power off

Done some more fiddling with the laptop.

I read somewhere that the eeprom can corrupt so decided to remove it and check it. I dumped and rewrote the original eeprom back after blanking and it verifies fine. It's not auto detecting the chip type though which might be an indicator of it not working or something?

With the eeprom installed it keeps cycling power on/off. With it removed it comes on with the leds on the keyboard flashing constantly. The fan isn't spinning at all now but i'm sure it was before.

I tried writing another S752 bios and eeprom found on this forum but that didn't change the power cycle behaviour. I think I'm going to try changing the eeprom chip and maybe use the bios posted by ridamouh159 in this E752 thread.