Friday, June 29, 2012

How to fix if DELL Laptop not recognizing adopter which is working on other laptops

Hi friends, Today I'm going to share a solution for DELL's Inspiron, Latitude, Studeo, XPS, Alienware or all other DELL laptop series which comes with the center pin power adapter 65W, 90W and 120W.
As laptop turn switch on with charger 
plunged in (adapter). BIOS shows an error on start up screen.

The AC power adapter wattage and type cannot be determined
The battery may not charge
The system will adjust the performance to match the power available
Please connect a Dell 65W/90W/120W AC adapter or greater for best system performance
To resolve this issue, try to reseat the power adapter.
Strike the F3 key (before the F1 or F2 key) if you do not want to see
Power warning messages again.
Strike the F1 key to continue. F2 to run the setup utility
Press F5 to run on board diagnostics.

In CMOS setup the BIOS shows AC adapter Unknown or IDLE. It will not charge the battery.
If you connect charger after boot laptop by battery the OS windows show error 'PLUG IN NOT CHARGING'

In first look every engineer will be quite certain on that the power cable of AC adopter had broken internally due to the constant flexing and this is case to plug . This happens on almost every laptop power adopter.
In my last few years service I found 95% fault in dell A/C power adapters in this is that adapter not recognizing case.
This kind of faulty adapters mostly ID pin of charging cable has found temped or broken Due to this laptop unable to recognize the charger wattage.
This center of dell adopter knows as ID pin of adopter.
Every time this is a very easy to fix this fault for a person who just know decent enough about soldering and basic electronics stuff like continuity testing and voltage measurement.
but if adopter is working fine with any other laptop then how we can fix the problem.

So dear friends, In this post I will tell how to repair any dell Laptop charger not recognizes by BIOS. And not recognizing the working OK A/C adapter.
If you having same problem with any DELL laptop first of all check the basic things.
Get a faulty motherboard out from laptop first with the eyes sweep it and see no didn't burn out marks, there is no damage to the skin and see whether the various plugs, socket-outlets skew, resistance, capacitance PIN is met and the surface is burned, the chip surface cracking, motherboard copper foil is blowing. Would also like to see if there are any foreign objects into the motherboard components. Encounter questionable places.
Check DC jack, connector or cable for proper connecting between DC jacks to main board if present.
Then start the next step by testing the voltage or components one by one
The best thing in DELL is they most likely be using same circuit in their all models so this thing make it easy to repair for all models.
I have a circuit which has answer of our problem. But fist of all need to know something very important things about Dell's adapter.
Time to get know how the adapter data signal goes to I/O, basically there is a ID input comes from DC connector to the N-type Mosfet drain and the souse of type Mosfet connected with the I/O chip using a resistance in series. Gate of the Mosfet controller by a protection circuit commonly there is a NPN transistor you can see circuit diagram.

I draw a small circuit to understand how DELL charging adapter's ID data get in to main board of laptop.
Note:- Components number and value can be change! 

Now I going to show a image of a dell studio laptop's main board in the board you can see clearly a brunt component this is the driver Mosfet that I draw earlier diagram.
In this blow image you can see mosfet brunt this is the first mosfet that make id pin input as well as it’s work as a switch for protect the motherboard from unwanted leakage power supply.
This image taken of dell Studio 1950 in this laptop working okay on battery but as we connect the ac adapter to laptop can’t recognize the A/C adapter and shows the error on screen.
POST screen error and in windows shows ''Plug in, not charging''.
This laptop is very easy to fix because we don’t need to search fot a faulty component this automatically shows as we open the motherboard brunt components tell me all things that I need.

Mostly plugin not charging case happens due to this mosfet failure and not every time you gonna found this tinny mosfet brunt! Keep remember in electronics any component can be faulty even its looks okay from outside.
Note:- Do not replace directly if found mosfet brunt or fault
y! Please also check the fuse and N-P-N transistor before you do this operation.

In the last image i drew some voltage that rating on some points that may be help you to trace the circuit in any other dell's mainboard.
If you found every component fine also voltage are fine but still laptop not recognizing the adapter then resold the I/O chip first after this still you having problem then replace the I/O chip.
have a good luck.