dell latitue e5450 AC Adaptor unknown

[apostsamking]

Hello everyone hope all is well. Pls I bought this second hand dell latitue e5450, I realize that the battery cannot be charged because it says ac adopter unknown at bios. I tried several chargers but still I get the same messageAC Adaptor unknown. So I open the laptop up checked the motherboard and i realised that the diod PD5 is fried so I changed, but I still get the same message, changed even the charging ic still the same message AC Adaptor unknown. Can any one help me?

[mon2]

Re: dell latitue e5450 AC Adaptor unknown

The fault is linked to the PS_ID circuit. See attached. A number of components exist between the PS_ID pin on the power adapter connector and the EC IC. The EC is the controller that communicates with the power adapter using the single-wire protocol. The single-wire protocol is well documented by Maxim / Dallas Semiconductor and there are a number of 'hack' articles on how to emulate the same using other ICs. Once the logic board is pacified that the proper adapter signature is present, the logic board will remove this message and allow for a normal operation.

If PQ2 or perhaps PU1 are defective, the adapter communication cannot proceed and then the logic board defaults to the 'unknown adapter' message.

Suggest to remove and bypass PQ2. Be sure to download a datasheet for this mosfet so that you can review the exact pinout for this SOT-23 package.

Then bypass the source & drain pins with a piece of wire and test again.

If it works, which is often the fault, replace this PQ2 with another.

Otherwise, proceed to review and replace PU1.

During this review, do measure the voltage to ground of the PS_ID line before and after PQ2.

[mcplslg123]

Re: dell latitue e5450 AC Adaptor unknown

Make sure PR9 is exact 33 Ohms.

[apostsamking]

Re: dell latitue e5450 AC Adaptor unknown

Thanks Very much, I will work on it and give you a feed back. Thanks once again.

[apostsamking]

Re: dell latitue e5450 AC Adaptor unknown

I did everything but I still get the ac adapter unknown

[mon2]

Re: dell latitue e5450 AC Adaptor unknown

Post the voltage the ground of PS_ID.

Also share the resistance of the series resistor in the circuit.

Is it 33 ohms? No power when checking the resistance.

[apostsamking]

Re: dell latitue e5450 AC Adaptor unknown

It was no power when checking the resistance.

[mon2]

Re: dell latitue e5450 AC Adaptor unknown

Ok, but what is the resistance across PR9 ?

Next, power up and with the meter in DC volts mode -> check the voltage to ground of this line.

Check the voltage at the power adapter connector and again after the mosfet that you have bridged.

Post each measurement.

[apostsamking]

Re: dell latitue e5450 AC Adaptor unknown

I get 0.169v

[mon2]

Re: dell latitue e5450 AC Adaptor unknown

This line should be at a higher voltage.

Can you post a pick of the mosfet bypass wiring?

[apostsamking]

Re: dell latitue e5450 AC Adaptor unknown

Pls show me I don't know how to go about it.

[tomodachi]

Re: dell latitue e5450 AC Adaptor unknown

Can you check whether PD5 is good or not ?