For the Systematic maintenances of laptops we need the tools listed below. The Technician must have strong platform in Electronics and computer technology. With out this you can do little things such as replacement of LCD, Key Board, Cursor controller (navigator), Battery, RAM, HDD, DVD, MODEM and DC adapter etc…. and also you can do something as regular hardware technicians do like partitioning, formatting, installation of operating system(s), Driver Loading etc..
Real Repairing
Before you unscrewing laptop setup a screw box having multiple partitions, each partition should be labeled as #1, #2, #3 etc. Keep each screw in its partition according to its size in screw box. DON’T TOUCH any inside parts of Laptop without wearing an antistatic wrist strap
Common fault and remedies
System Dead – Any kind of response is not getting when power button is pressed.
Check the DC adaptor by putting a 12V 50/36-Watts automobile head light lamp and ensure the voltage stability of the DC outlet. If the DC source is normal, you can think of battery, if the battery has any internal short or it produce fake feedback due to the failure of internal protection circuit can cause system dead
An advisable remedy for the battery problem is simply - replace battery. Battery is a costlier thing, if you are so creative you can open battery and can fiend damaged cell(s)And component in protection circuit replace the damaged thing with new one or from similar battery (If the Battery OK you may be get money for 2 bottles of JonyWalker black label) If the DC source and battery are normal you have take the laptop for a surgery
Laptop surgery
Tools
1.Philips head screwdrivers 2.flat head screwdrivers 3.Twiszer (long sharp head)
4.30Watts Soldering Iron etc.
Equipments
1. 20 MHz oscilloscope with long sharp pin probe, 2.20Killo Ohms/Volt Multimeter, 3.Universal Flash Programmer and, SMD Rework Station
Consumables
1.Solder Wire, 2.Flux (paste not Liquid) 3.Alcohol (Not to Drink, just for cleaning Board)
Software & Firmware
exe file for the Programmer, BIOS Firmware from www
Dileep's Method
1.Remove all the attachments and peripherals. 2.unscrew as I said early. 3.Feed D.C from adapter to the main board alone. 4.turn on your oscilloscope, set its V/Div to 5v &Time/Div to get a study line. 5.connect the GND together and keep the probe in the hot end of the power switch now the oscilloscope shows little bit high, if you press power button this high become low at the moment, If not happening so, change that switch.
Don’t relax
While your investigation progress you may be turn at 5th point of above paragraphI.e. you can’t find a high at the hot end of the power switch. Yah deeply in trouble if you want to forward you need circuit diagram or experience, anyway you have to find power IC and related components. Basically this is a PWM circuit for power regulation Consisting of PWM generator IC and MOSFET s. Check the suspected component with your multimeter and replace using hot air/soldering iron
Golden Tip: If high is there in the hot end of power switch and it is become low while pressing power button. Connect your scope to gate pin of the FET, and then press the switch if you see anything abnormal than a rectangular wave. You can ensure the FET is damaged, if you test the same FET with a multimeter it may be good but it goes leaky 'in-circuit' operation. On the main board you can see many PWM & FET circuits. The INTEL calls this circuit as VRM – Voltage Regulator Module. After pressing the power button you should ensure the propper work of VRM s by oscilloscope. (Check the rectangular wave at the gate of FET)
Wide vision about dead system
Another possibility for dead system is missing clock! How to fined clock? The clock is generated from a crystal, an IC locates near this crystal, and this IC is a DIL (Dual In Line package) SMT (Surface Mount Terminal), You can download Data sheet of this chip and check the output. If the clock is not coming the crystal or clock IC may be damaged
Silver tip :
For maintaining RTC (real Time Clock) a 32.786 KHz Tubular crystal is used, failure of this results dead system
Problem not yet solved?
Peel the sticker over the Flash BIOS IC, note the serial Number and download data sheet, and identify its address pins A0 to A7 Test the presents of address signal at the A0 pin of the BIOS IC, if the address signal is not coming either the Processor or North Bridge IC is damaged. You can ensure this by substituting a new processor. If the damage is due to North Bridge Absolutely “We can do nothing” Now you want to know about North Bridge IC? Actually its scientific name is Graphics and Memory Control Hub (GMCH), but our Uncles in INTEL put this pet name North Bridge. He locket very near to Processor and
performs many functions
*****Can be do manyyyyyyyyy things *****remaining part will be published on request
dileep1973@gmail.com
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