Lenovo W541

[bjhawfam]

Working on a Lenovo W541 motherboard LKM-1 WS MB 12291-2 ... The issue was a water spill/liquid damage to the board. The damage was limited to the bios region. Originally there was no power to the board, there was damage to pin 7 & 8 on the bios chip in the photo, the pins had corrosion as well. Removed the bios and was actually able to make a copy of the bios (not sure if its a good copy).. I than flashed a new bios chip and cleaned the area that was affected, replaced the new bios chip and now I have power to the board. The only issue is now it turns on the fan spins then slows down and spins again, over and over this happens... The power button board lights up and stays on, however
every time the fan restarts the light dims and like its resetting.. Also the power button plays no part in starting or stopping the laptop, once powered the laptop starts automatically, as if there's a short. My question, where would a short on pin 7 & 8 come in at?

Voltages on the bios chip are as follows when powered on

pin 1 = 3 vdc than goes to zero and shoots back to 3 v
pin 2 = 1.5v than goes to zero and starts over at 1.5
pin 3 = 1.5v than goes to zero and starts over at 1.5
pin 4 = 0v
pin 5 = 1.2v than down to zero and back to 1.2v
pin 6 = 1.3v than down to zero and back to 1.2v
pin 7 = .5v than down to zero and starts over
pin 8 = .5v than down to zero and starts over

behaves like a short causing it to restart over and over? Any advice? could not find a schematic...

[caspian]

Re: Lenovo W541

try to find the schematics. try to find which coil has such a fluctuating voltage.

[bjhawfam]

Re: Lenovo W541

The 3 coils furthest from the bios are the only coils that exhibit this behavior.. The 3 near the RAM slots, though the voltage is small they all behave the same.. Tried to find a schematic and still looking, even if I had to pay I could not find a schematic yet, still looking.

[caspian]

Re: Lenovo W541

how much voltage on the 3 coils approximately? are all the other coils with no voltage?

note: please save photos in JPEG format. so they get smaller file sizes.

[bjhawfam]

Re: Lenovo W541

The 3 have .5v than they drop to zero and repeat over and over. The other coils have constant voltage 3v,, 5 volts and .5v in and out... Just keeps repeating over and over.

[caspian]

Re: Lenovo W541

now you need the schematics to trace the mainboard to discover why some coils do not have correct voltage. In addition, look at all the ICs carefully. you may discover another IC with corrosion which you did not consider before.