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.

Thursday, April 19, 2012

How to fix Dell BIOS 8 beep error.

In this post I'll  fix a Dell n5110 laptop that beeps on start-up but nothing comes on laptop display screen. This post will also help you to fix the same problem other Dell laptops.

The beeps that come on start up that is a POST error generated by the BIOS.
I download this table form the Dell support site in this table dell defined the cause for problem as the number of beep codes.


POST Beep Codes
Beep CodesErrorProbable Causes
1Memory refresh failure.Defective system board.
2Error occurred in first 64 KB of main memory.Faulty DIMM or defective system board.
3Read or write error occurred in first 64 KB of main memory.Faulty DIMM.
4Timer on system board malfunctioned.Defective system board.
5Microprocessor error.Defective microprocesor.
6Gate A20 failure.Defective system board.
7Microprocessor-execption interrupt error.Defective microprocessor.
8Video memory read/write error.Missing or faulty video adapter.
9ROM checksum value does not match value encoded in system BIOS.Corrupted system BIOS program or defective system BIOS chip.
10NVRAM shutdown register read/write error.Defective system board.
11Cache memory error.Defective microprocessor or cache card.
1-2Video adapter failure.Faulty video adapter.
1-3No monitor connected.Loose video cable connection or defective video cable.
Faulty video adapter.

In this table Dell says that the meaning of 8 beeps on star up cause to ''Missing or faulty video adapter'' but practically I always found something different that dell says!
In the first video you can see the as I turn on the Dell Inspiron n5110 laptop it's star beeps, 8 beeps but nothing appear on display screen.

In the second video i connect an CRT monitor for external display and in this monitor display comes okay.

Remove the laptop top cover assembly you will get an access to the laptop display connector  and unplug the display connector and re-install  it again. In the last video you can see it's work for me the  display coming on the laptop screen and no any beep error appear.

Now I write something for those who are facing the problem but didn't got success to fix this fault.
Because not only this display cable loses connection is responsible to that malfunctioning of laptop. There  is some other things malfunctioning can be responsible to the same error.

  • LED/LCD (due faulty or broken screen).
  • Display cable/Video cable (due to broken or shorted cable).
  • system board (broken display header or jack, faulty graphic card/chip or video ram).

        If the external monitor works fine with the faulty laptop then practically 95% problem should be happens due to LED/LCD screen or faulty video cable. rest 5% case can be happens due to motherboard and video card problem.
        But the external monitor also not shows any display then definitely it's a system boaerd problem and it's mostly happens due to graphic chip malfunctioning, need to replace, re-ball or reflow the chip using the BGA rework station.

        Thanks and have a good luck

        Monday, April 16, 2012

        How to fix USB port if still not working after tried everything with Windows/Mac and BIOS settings also.

        A common problem that arises for computer users is dealing with the USB Device not recognized error. This error is thrown after an USB device is connected to the computer but is not automatically detected.
        When the error occurs, the Windows Device Manager may also list the component as an "unknown device" depending on the type of error.
        Or the Laptop/Desktop completely unable to detected any electronics USB device no any error has shown on the display.
        Some times computer only detect few hardware that don't  draw power from the computer via the USB connection like printer and many other hardware that requires external power source to work.
        Now let me divide this USB problem to parts to easy understand and diagnose the fault for both USB 2.0 and USB 3.0 :-
        1. Laptop not detecting any electronics device which draw power from USB port like pen-drive or any USB device (USB 2.0 & USB 3.0) detected.
        2.  Laptop detecting the hardware witch plugged in the USB 2.0 or USB 3.0 port but not recognizing the hardware device (error pop up shows  "USB not recognized")
        When you switch on the computer or connect any USB 2.0 or USB 3.0 devices, a BIOS message or Windows message may be displayed such as:
        • CMOS checksum error.
        • USB device overcurrent status detected.
        • Error 0701: USB Over Current On HC/Port - Bus:00H Dev :1DH Fun:01H / Port:00H
          Error 0701: USB Over Current On HC/Port - Bus:00H Dev :1DH Fun:02H / Port:00H
        • Error 0701: USB overcurrent error.
        • USB Device error.
        • Shutting down in 15 seconds
        1. Device recognized on normal 2.0 but not on 3.0.
        Make sure before you read this solution, you made sure that everything is okay on the software side your device driver and OS settings like ''USB 2.0 or USB 3.0 Hub Power Management should be disable or have configure correctly and also BIOS settings are configured correctly and up to date. Make sure that USB is enabled from bios settings.
        Before I stat the solution of this problem let me introduce some basic thing about the electronics behind the USB.
        We have two type of USB.
        Both power up the device from +5v  Vbus pin to power up the small USB devices like pendrived and mouse  the difference is USB 3.0 has double data lines for Superspeed high speed interface.
        Both port detect any device by their data lines.

                        USB 3.0 standard pin out
        +5V Power
        USB D-
         USB 2.0 data
        USB D+
         Ground for power return
         SuperSpeed receiver
         SuperSpeed receiver
         Ground for   signal return
         SuperSpeed transmitter
         SuperSpeed transmitter

                      USB 2.0
        +5 V
        Data −
        Data +

        1. Laptop detecting the hardware plugged in the USB port but not recognizing the hardware device (error pop up shows  "USB not recognized")
        If the +5v is okay on the port and the system only detect  the hardware not able to recognize the hardware that means something is malfunction in the date lines tracks form USB port to south bridge. Check the coils and fuse able SMD resistor for open which are connected in series of data liens with the malfunctioning port. If coils not found open then heat up the complete motherboard using the hot air gun. 
        Make south bridge and the nearly components of USB port  you main focus when to heating up the main board. After did all thing if you sill have problem then it means south bridge is dry-sold or the some track is broken on main board.
        now only two things can be done to resolve this problem..reflow or reball the south bridge.
        if this 'not recognizing' problem comes with the all ports of laptop or desktop board then the problem happens due to BGA south bridge if you already tried bios reflashing.
        But don't worry i m not gonna tell that the time is to change the south bridge. Because it's pretty risky work to replace a big BGA chips on a laptop motherboard. 
        Just you need to re flow the south bridge using a simple hot air gun or a IR BGA rework station.
        You can see my older post if you gonna use the simple hot airgun to reflow you south bridge.
        Be carefully because if you not ever had any BGA re flow. a mistake can be damage your main board or the chip.

        2. Laptop not detecting any electronics device which draw power from USB port like pen-drive or any USB device detected.

        This problem is related with main board of desktop laptop computer. If you facing this kind of problem then first thing that I would like to let you know that is this problem happens due to the missing +5v on the port. because if laptop not able to detect device that draw the power from the USB port to working like pen drive mouse keypad. If USB device didn't get the power how they will work?
        In every laptop and in some desktop mother board manufactures use a switch circuit for power management and protect the motherboard from shorted USB device and to protect form overload. Mostly you will found the VBus pin fuse open or the switch IC faulty.
        This switch is normally is a SMD chip that provide the power. Each and every USB port can be have a single chip as there power management switch and also a chip can manage two or more port depends on the manufacture.
        So simply take out the motherboard of laptop on your working desk and trace out the track of VBus of the port that malfunctioning and check the fuse or coli for open if this used in series of . pin to USB power manger chip. if it's okay then now check the input voltage of chip if available  first of all resold the chip and then make sure chip gets the enable signal is available on the chip. you can download the chip data sheet to know the pin details of chip. But as per my experience you don’t have to download the chip data sheet because mostly laptop have same chip for every port so it's easy to diagnose that chip has problem or not. Simply check the same voltage on the so this fault happens some of reasons if you ever plugged in any sorted USB device in USB port or due to port broken and also can be happens.

        3. When you switch on the computer or connect a USB device, a BIOS message or Windows message may be displayed such as:
          • CMOS checksum error.
          • USB device overcurrent status detected.
          • Error 0701: USB Over Current On HC/Port - Bus:00H Dev :1DH Fun:01H / Port:00H
            Error 0701: USB Over Current On HC/Port - Bus:00H Dev :1DH Fun:02H / Port:00H
          • Error 0701: USB overcurrent error.
          • USB Device error.
          • Shutting down in 15 seconds
        If you get the this kind of error message on starter (POST) screen wham you turn on the laptop or desktop computer than that meas any short circuit in the USB port.
        So simply check the port for physically broken normally the broken USB socket is the most reason of shorting in USB power supply line.
        if no any port the seems like broken or short the problem will can be in USB power manager chip simple check the USB  VBus  shorting with ground.
        Laptop USB Power Supply Circuit 
        And the good news if you have problem with USB power chip and it's availability is out of reach from you then u can easily bypass the USB port supply... remove the USB power chip and just short the input and output track of chip using a wire.


        4. Device recognized on normal 2.0 but not on 3.0. 
        If USB 3.0 device not recognized by the usb 3.0 port and your hardware device and the settings of USB is seems okay then check the StdA_SSTX, StdA_SSRX pins or and coil for open and dry.
        Resold the coil and USB header.
                                       HP LAPTOP 4350 USB 3.0 

        Sunday, December 25, 2011

        How to stop laptop overheating, if still overheats after cleaning dust.

        There is two kinds of overheating.
        1. Component specific overheating, caused by CPU or Graphics Processing Unit (GPU).
        2. Overall temperature inside the laptop, caused by HDD and Battery.

        99.9% cases its CPU,GPU or North bridge (if no GPU present). But in these 99.9% cases sometimes its not just gets fixed by cleaning the dust from heat-sink vents.

        I am assuming you failed to fix overheating problem by following-
        • Removing dust from laptop heat sink.
        • Changed fan settings in CMOS.
        • Update the bios with new version.
        • Replaced the CPU cooling fan and graphics processing unit cooling fan (if present)
        • Tried a costly branded thermal past or thermal pad.
        Overheating happens because of dust, fan failure, loose heat-sink or broken heat-sink. Laptop gets overheat even if you don't run heavy CPU intesive software or graphics on the laptop and all above listed things seems okay.

        But Laptop produce huge heat even you runing on lightweight programs like notepad or working on CMOS setup screen. This problem is with all the laptops those come with the graphics chip. When the BGA graphics chip get little dry-solder or comes to the end of the life.

        Overheating is the most common reason when you see your laptop work for a while and then  freeze up, shut down on its own or even restarts while still plugged in charging. It all caused by CPU overheating.

        If CPU overheats then first of all try to change it with same working CPU. If Same problem exists after replacing the CPU then change the CPU core voltage VRM section's SMD electrolytic capacitor or PTH (non SMD) electrolytic capacitor placed near the CPU socket.

        In the case of GPU overheats it usually hangs or restarts. IF you having problem with graphics processor you Just wait for when your laptop GPU goes down. Then it will be the right time to re-ball or re-flow the GPU chip. Or you can extend the life of your GPU chip just following these instructions.Heat is a killer for electronic devices and Laptop cooling fan play a most important role to save the life of laptop. Manufacturer use a smart fan circuit for their cooling fan and fan speed is also controllable. So a well designed laptop will run the fan just fast enough to keep the temperature in the ideal operating range. But as laptop grow older it's effects the fan performance also.

        Let see what we can do for expanding the life of our laptop if it's nearing the end life of it's motherboard. In my last post I was talking about the CPU cooling fan.
        This is the most powerful part of our laptop that can make a laptop life long and smooth. so I am going to do something with the CPU cooling fan smart circuits that usually control CPU cooling fan speed so if laptop gets overheat it means there is something missing or wrong.

        In very easy way we can ride over the smart fan controller circuit just disconnect the PWM controller pin from fan header it's very easy way to prevent our laptop from overheat.
        After the opening connection of PWM signal fan runs on the same speed it's never gets down in the normal mode but it will be remain off if smart fan circuit will stop fan.
        We just bypass the fan speed control some time laptop gets overheat after repairing motherboard BGA chip, Re-ball the GPU or North-bridge due to faulty chip or if it not placed perfectly on motherboard then also we have to bypass the cooling fan for good ventilation.

        Hope this helps let me know problems/queries in comments section below.

        Wednesday, August 31, 2011

        How to fix keys on laptop keypad not working even keypad already replaced.

        If you replaced the keyboard and the same exact keys are still not working then you most likely have a system board issue.
        But check basic things and make sure before turning to any chip level operation that did you insert the cable properly and is your zip connector or header of keypad is good or broken from anywhere?

        Some of my known people who connected with the laptop computer hardware repairing filed but they don't done any chip level work on laptop so they use to send me the faulty laptop for repair in which they feel a chip level issue they do only diagnose and fix only software and common hardware level problem like installation of software, OS and part replacing work replace hard drive, ODD, LCD, Keypad, Touch-pad, Hinge and main board but replacing main board is too much costly.
        Some time problem can't get fix after just replacing the part that they think is a faulty spare because they do repair on the basic diagnostic way if keypad not working ( problem can be some keys not working or functioning properly, keypad died not detected at all ) after checked some basic thing like OS issue driver and finally replaces the keypad as usual we all have to do.
        But if problem couldn't get fix then its means problem is not a normal issue that will need a chip level operation so as usual they forward me this case. When they come to me most likely they said ''I have replaced the keyboard on this laptop 2, 3, 5 times but sill keypad not working.” These same letters stop working after a while. Replacing the keyboard worked before'' also most of the time same thing happened with mouse touch-pad.
        Before I going to tell how can easily repairer this kind of case..I just want to remained you a basic block diagram of laptop motherboard.

        As this diagram keypad and touch pad PS/2 controls are controlled by EC chip and if EC chip not present than I/O chip controls the PS/2 control.

        Every laptop notebook manufacture uses a different type keypad model and their header for their different laptops models. And there header size and their pin datasheet may not be same. so before wasting your time to get datasheet and any other solution to fix the problem to searching on Google just re-soled the I/O chip and pull up resistor pack capacitor pack or simple SMD resistor which have connected with keypad connector and direct with I/O chip because today laptop manufactures use the I/O chip which have in built EC controller.
        You can use hot air blower or a micro iron for re-soldering process… mostly pull up resistor and capacitors has solder nearby the keypad connector or header.

        Pay little care if you have not familiar with SMD components.
        If after re-soldering can fix you problem then you must have to change the EC or I/O chip :(
        have a good luck :)

        Thursday, August 4, 2011

        Power up a laptop motherboard without power button or power strip.

        Yes we can power up a laptop without connecting it's power button board or power strip..!! same as a desktop mother board.
        It's safe as well as desktop motherboard just you need to know how power system of motherboard is functioning or how it's work as we press power button.
        Switching the power 'on & off' is done by circuits on the motherboard.The circuits are triggered to change state by a momentary shot circuit of two points in the circuit. That is done by the push power button. A short-term connection of that button is enough to turn on motherboard. Usually one pin of on/off switch is shant with (ground) GUN. and second pin of on off switch connected with the circuit and always there is stay a (very low power +voltage) high pulse on the track of the power switch as we press the on off switch switch shot the high plus with Ground. and due to ground, plus trun down to low '0' and circuit turn on the motherboard.
        Power on and off system controlled by super I/O chip on motherboard of laptop or some time some motherboard manufacture use some component (IC,Mosfet, Transistor) interface between power button and in I/O (input output controller) chip and mostly power switch being connected direct with I/O.

        Is it a safe and easy method to on and off motherboard without connecting POWER button PCB or strip while repairing? :-

        It is a good and easy way. If you repairing a major fault of laptop motherboard and while repairing there is need to power up motherboard many time and i think you already know what can be happen if we connect and disconnect a ribbon flex cable many times from connectors, connecting tips of the ribbon flex cable may be get tempted and brake! and it is very hard job to recondition a tempted or broken ribbon cable, even it's also a hard and time consuming job if you looking for a same new one cable in your local market.
        So that is a very most common problem with flex cables.

        How to find a ON and Off button logic track (PS ON signal) on laptop motherboard :-
        It,s very easy to find out form where we can turn on a laptop without connecting it,s on/off switch PCB.
        set the multimeter on continuity or buzzer range And simply trace the power switch non ground track from switch to it's ribbon flex cable or connector.

        follow this video....


        And in some of laptop main board you will found a already not connected tips for power on off function, So I putt here a image of this kind of laptop motherboard it's image:-

        ON board power on,off tip of:- Compaq Presario V6000,Compaq F700,HP Pavilion DV6000 series,HP Pavilion DV9000 Motherboard,hp pavilion dv7.

        But mostly we have to find the PS ON track on main board with the help of continuity meter. :P

        HAVE A GOOD LUCK :)