Member Avatar for the_jazz

Hello,

I have pulled out my hair over this one for so long, couldn`t find the answer.
Practically i have good experience with disassembling laptops, soldering, changing parts and so on. But this one is over my head!

So, a friend of mine gave me his AMILO L7310GW notebook with a power problem. Laptop powers on, you can hear the fan spinning for 5 seconds and then powers off again. Than again, powers on (by itself), 5 seconds spinning (no post no nothing) and powers off. Infinite loop until i plug it out of the power adapter. Since my friend used his laptop (when it was still working) on a lan cable, so, i thought that the integrated lan card may be blown out and creating a short circuit on the motherboard. I disassembled it, soldered out the lan chip - no change at all. Soldered out the bios chip, put it on a programmer, put on fresh new (last) bios - still no change. Tried swapping ram, different power adapter (same voltage), hard drive, CPU, everything i could think of. Also done BGA reballing on the VIA video chip, and VIA chipset.

So after a month and so - nothing seems to be changing the picture. Infinite power on/off loop. I`m pretty sure that this is major problem, but i had to try here :)

Any ideas how to make it work?
Thanks

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  • Latest Post Latest Post by caperjack

Dani AI

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Short summary and context: the symptom described by — fan spins for a few seconds, no POST, then the machine shuts off and repeats — makes an OS reinstall (as suggested by ) irrelevant because the board never reaches POST. This pattern almost always means the board’s power‑sequence or protection circuitry is collapsing, not a software fault.

Probable areas to focus on (priority order): the DC‑in / VIN section (jack, current‑sense resistor, MOSFETs or charging/PMIC), the Super I/O / embedded controller that controls PWROK / RSMRST / SYS_ON timing, and decoupling / bulk electrolytic capacitors or VRM components. Failures in any of those will allow the board to try to start, then cut power when a rail or PG signal fails. (pdfcoffee.com)

Practical, board‑level checklist (assumes soldering and meter experience):

  • Put the battery aside and power from AC only; unplug HDD/ODD/WLAN/LCD connectors so only the bare board (CPU, RAM, PSU) is present.
  • Use a bench PSU with current limit (~1A) to see if the board immediately draws fault current; note where the current spike occurs and which component heats.
  • Probe for 19V at the jack, then for the always‑on/standby rails (3.3VALW / 5VALW and 3.3VSB / 5VSB) and watch whether they collapse ~5s later. Probe PWRGOOD/PWROK, RSMRST and SYS_ON lines around the SIO (service manual / schematic needed to find test points).
  • Visually inspect and ESR‑test electrolytic caps around VIN and VRM; replace any bulging or high‑ESR parts. Thermal/infrared checks often reveal the hot shorted MOSFET or regulator quickly. (studylib.net)

Use the model’s service data before part swaps: the AMILO L7310 family has published service documentation and board identifiers to locate VIN, SIO and test pads — consult the L7310 service manual and schematic listings when identifying parts and test points. Replacing or isolating the power MOSFETs/charging IC or the SIO/EC is a common final step when rails collapse but GPU/Northbridge reflow did not help. ()

References: Fujitsu Siemens L7310 service manual (https://manualmachine.com/fujitsusiemenscomputers/l7310/8351260-service-manual/) ()

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Member Avatar for caperjack

Infinite power on/off loop

i have seen this fixed by simply re-installing windows

Member Avatar for the_jazz

This would be the simpliest thing to do, but...only if the notebook really gets to loading OS (which it does not). The infinite power loop is in the beginning (before post screen, before everything). I never reach loading OS.

Any other ideas?

Member Avatar for caperjack

no sorry ,by the look at what you did already to try and fix it you know about laptops that I ,sorry

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