Lenovo t440s nm-a052 dead bios chip

[kuraimangetsu]

Hi guys
i got a dead t440s the bios chip is "W25Q128BV"
testing with multimeter all good as i think
but i get a 0.052 on the 1th PIN of the chip

if i remove the bios i get the same 0.052 with the adapter removed
and 0.024 when i plug the adapter.

so what do you think?

[mon2]

Re: Lenovo t440s nm-a052 dead bios chip

Pin #1 = /CS = CS#.

This is an active LOW chip select pin. If the voltage is low, the chip is being selected. This voltage may also be low if the power rail is missing for this group of pins.

A multimeter cannot monitor the activity of this pin if it is toggling high and low. You will need a scope to view signals that are switching at any speed. Or a logic / bus analyzer like Total Phase SPI bus tool. Then you can log the data being extracted out of this flash memory device upon boot.

I would check the voltage to ground of each pin on this flash device. Post the list

Also confirm the presence of the other voltage rails on this logic board. If a voltage rail is absent, power down and configure the meter to resistance mode. Measure the resistance to ground reading of that power rail.

[kuraimangetsu]

Re: Lenovo t440s nm-a052 dead bios chip

Pin #1 = /CS = CS#.

This is an active LOW chip select pin. If the voltage is low, the chip is being selected. This voltage may also be low if the power rail is missing for this group of pins.

A multimeter cannot monitor the activity of this pin if it is toggling high and low. You will need a scope to view signals that are switching at any speed. Or a logic / bus analyzer like Total Phase SPI bus tool. Then you can log the data being extracted out of this flash memory device upon boot.

I would check the voltage to ground of each pin on this flash device. Post the list

Also confirm the presence of the other voltage rails on this logic board. If a voltage rail is absent, power down and configure the meter to resistance mode. Measure the resistance to ground reading of that power rail.

pin1 and pin2 have 0.052v adapter connected
pin1 and pin2 have 0.024v adapter connected

pin1 and pin2 have 80.0 kohm res to gnd adapter connected
pin1 and pin2 have 0.900 mohm res to gnd with no adapter connected


other voltage rails
1.2
5.1
3.3
present

[mon2]

Re: Lenovo t440s nm-a052 dead bios chip

Never check resistance with power to the board.

Confirm other power rails at each inductor on the board. The fault may be due to other missing power rails.

[kuraimangetsu]

Re: Lenovo t440s nm-a052 dead bios chip

Never check resistance with power to the board.

Confirm other power rails at each inductor on the board. The fault may be due to other missing power rails.

here's an image for the readings

[mon2]

Re: Lenovo t440s nm-a052 dead bios chip

The 0v inductors are likely the CPU rails. Often multiple rails will be used to share the heavy currents and are split in phases of turning on/off cycles.

Remove all power. Meter in resistance mode.

Check the resistance to ground of these inductors.

[kuraimangetsu]

Re: Lenovo t440s nm-a052 dead bios chip

after digging it was the "vcc3lan" mosfet that wont open to the resistance. so after jumping the mosfet pin to the resistance i got the 3.3 on the res and got like 1.3v on the pin1 bios.
removed the caps connected to vcc3lan that i think it's shorted and got back the 3.3v on the bios

[mon2]

Re: Lenovo t440s nm-a052 dead bios chip

Very good. So the laptop is repaired and working now?

[kuraimangetsu]

Re: Lenovo t440s nm-a052 dead bios chip

Very good. So the laptop is repaired and working now?

Sry. for the late replay.
yeah. it's working right now.

attached the jumper location on the Q69 to the resistor

[andree952]

hi can you say which ones capasitors do you have removed?