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BASIC DIAGNOSTIC REPAIR

**THIS SECTION IS STILL UNDER DEVELOPEMENT**

Operating System/Mac iOS not loading or Overheating and Servicing

-Windows or Mac iOS not loading > Check Hardwares HDD/SSD > If Hardwares OK > Reinstalling Operating System. Before reinstalling Windows or Mac iOS backup data, to restore after repair is completed.

-Infected System > Virus scan the Hard Disk Drive and Remove Malicious files.

-Servicing PC, Laptop, iMac or Macbook > Full strip down and clean internals, check cooling fan,  inspection logicboard for any corrosions, check CMOS battery for correct voltage (if one is installed such as CR2032) otherwise invalid Bios setup post errors will appear.  Finally refresh thermal compound with good quality such as Arctic MX5. Also change thermal pads for GPU, PCH, etc. Reassemble the unit and run Burn In Test (Windows OS only), ASD on older macbook and iMac. On newer Macbook like A1708 and iMac using Apple diagnostic option.

-Breaking laptop LCD case/lid > slack the hinges by quarter turn anti clockwise to prevent further or future damage.  Macbook hinge are delicate and can be expensive to replace depending how the screen is assembled.

Inspect the DC/Adaptor charging port for any damaged or soldering defect or crack center pin > replace or resolder DC charging port otherwise laptop will not turn on or charge battery.

-LCD Screen faulty or cracked > replaced LCD with new good quality OEM spec screen like LG Display, Innolux, Samsung, AU Optronics, etc.

-Keyboard input errors > replace keyboard with new unit.

-Hard Disk Drive or Soild Sate Disk Issues > Check HDD/SSD for bad sectors or Smart error > Subject to error report > Replace HDD/SSD > Reinstall Windows/iOS and update drivers and security patch downloadable via operating system update utility.

-Some  beeps error on startup could related to bad RAM >Reseat RAM or Test RAM with softwares such as Memtest > Any errors replace RAM like for like. For example DD3L, replace with DDR3L only not DDR3.

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ADVANCED DIAGNOSTIC REPAIR

Logic board component level

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Laptops not turning ON. Logic Board Fault or DC charging port issues, inspect DC port for any damages and repair or replace if necessary. Also check power supply for correct input voltage with multimeter i.e. 19v present? If YES, check logic board power input 1st and 2nd Mosfets (refer to schematic diagram).

Mosfet has Source, Drain and Gate. No Voltage passing the Mosfets, check gate voltage depending on the type of Mosfet "PNP" or "NPN" the Gate voltage will be higher or lower than the voltage input at "Source". There are 2 type of Mosfet, "P" channel (Gate voltage needs to be lower than Source), whereas "N" channel (Gate voltage needs to same as Source or higher to pass the current). "D" Drain, "S" Source and "G" Gate.

NO voltage at Gate then trace back to the IC (QFN) responsible for creating the Gate voltage.

Check Voltage on the IC (QFN) such as VDD, VCC, VIN (these are IC input voltage), EN (enable voltages) are present? If all IC (QFN) input voltages are ok then check output voltage such as Gate voltage. NO Gate voltage means IC (QFN) is faulty, replace IC (QFN). 

                                            

                                                                             

 

A common issue with Logic board, is "Short" on one of it's power rail.  For example a SMD ceramic capacitor 0603 package on a 19v rail is damaged and sending the voltage to ground, this will prevent the logic board from powering up.  This is where some knowledge on component level repair is required to fix the logic board, hence it is not Rocket Science.  Several method can be applied to find a "Short". For example using multimeter in OHMs or Diode mode to find the power rail short (Low OHMs or Low Diode DC value will indicate a short). Once the power rail has been identified, use of bench power supply or short killer to inject voltage/current into the power rail will result in shorted component heating up.  This can be identified by use of thermal imager, spraying IPA 99% on the logic board since IPA is non conductive or touching the surface of logic board. If the shorted component is only drawing small amount of current it can be little difficult to indentify the short by touch or IPA. This is where a thermal imager can play a significant role of find a short.  You can only inject voltage into a power rail subject  to staying within it's therehold.  For example, you have short on CPU VCORE 1.2v dc powerline, your allowance is upto 1.2v dc, hence the AMPs could be virtually anything 2amps, 3amps, etc.

 

Laptop working with mains (AC/DC adaptor) but not charging battery.  DELL laptop charger has a small center pin known as ID pin (identification). This communicates between the laptop and the charger to ensure correct input voltage/amps is present.  If the ID pin is damaged laptop battery will not charge and error message will appear the BIOS post such as "unable to determine charger wattage press F1 to continue", on this instance replace charger. 

 

Bad battery is a common issues for laptop/macbook not charging.  Battery worn out due to age or overcharging or fully discharged to very long period, in this instance replace battery. Also if desktop task bar battery icons shows "not charging" or a caution sign over battery icon replace battery. However to properly check the charging circuit, laptop will need to be dismantled and conect the battery to the battery connector and check for voltages.  The battery positive (+) pins on the logic board will not give voltage until the battery is connected.  Once the battery is connected you should see voltage output on 2 positive (+) pins. For example the battery requires 10.8vdc to charge, the pin will have those voltages.  Also there several other pins located battery socket. Example, 2 pins positive, 1 pin Clock 3.3vdc, 1pins Data 3.3vdc, 1 pins battery sensor 3.3vdc (but this pin drops voltages to near 0.00vdc after battery is connect), 2 pins Ground.  Number of pins will vary from laptop to laptop. We check our laptop batteries with NLBA battery anayliser.

 

Faulty charging ic (eg. BQ24715) could also participate laptops working with adaptor not charging battery.  Need to check charging circuit and particularly input and output of the chargeing ic. To check charging circuit (refer to schematic to identify).

 

A corrupted BIOS (Basic Input Output Signal) controller IC such as Winbond 25Q64FVSIG which contains firmware can affect any PC from booting.  A EEPROM Programmer will be required to re-program the IC.  Sometime the BIOS IC becomes defective > Program and replace with new BIOS  IC.

Power on but "no display" is a common sympton, and mostly an issue with the logic board.  If resetting the BIOS or re-seating RAM doesn't resolve the issue then it will be a firmware issue or Logic board faulty i.e. faulty graphic chipset. Firmware > main BIOS or SIO/EC bios corrupted.  SIO programmer is required and connected via keyboard connector to reflash the SIO EC BIOS.  Also on new generation Intel Platform Processor logic board has "ME Region" Intel Management Engine or Trusted Execution Engine, which a small binary. Intel Managment Engine is a part of BIOS/UEFI/CSME.  It is responsible for adjusting CPU clock, EIST, power saving stages, etc.  There are two section in ME firmware CODE and DATA.  CODE is Engine firmware  and Data where all the system specifi setting are stored.  DATA section can be in one of  three states: Unconfigured, Configure or Initialized. a Corrupted ME Region can result PC having abnormal behaviour for example intermitant shut down, slow boot up, etc.  ME Region issues can be fixed via "Clean ME Region method.

 

 

 

 

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BGA REWORK

BGA Rework (Ball Grid Array).  This is know a "flip chip" with solder ball under the chip which make off the connection to the logic board once the chiopset is soldered on via rework machine such as Jovy RE8500.

 

This is a process where we change BGA flip chip (to be continued writing....)

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Maintaining Laptop battery

Battery problem is a common issue with your smart devices such as mobiles, laptops, tablets, etc.

Symptoms: battery will not charge or not hold charge, swollen or not detecting (laptops).  This is mostly due to a faulty battery. Some instances I could be the logic board fault within the charging circuit.

How to resolve and maintain battery / calibrated to prolong the life: Obviously new genuine or a decent after market battery (not the cheap knock-off from eBay). 

Knock-off batteries for Macbook can affect the logic board SMC or charging circuit.  After installing a decent new battery plug charging and full charge the battery until charge indicator reaches 100%. Do not charge the battery overnight. Once charge reached 100% unplug the charger and run down the battery until it reaches 10%. Re-charge the battery and repeat the process 10 times, I would recommend this because the battery need to calibrated. By charging 100% and disacharging to 10% both battery circuit board and laptop charging ic is kind of building a relation. Once calibration is completed the battery should not be fully charged 100%, only charge upto 85%. Also do not discharge battery below 20%. Charge and discharge battery through this method will keep your battery in good condition. For example: I have a Samsung Note 10 Plus, over 2 years old to date and the battery is still 100% healthy.  An average battery lasts around 4 years or more providing it is charged adequately. Some battery are designed to take upto 500 charge cycles, other high quailty battery upto 1000.  This charge cycle count down is programmed in to the charging circuit within the battery by the battery manufacturer. By charging the battery upto 85% it not registering a charge cycle which means charge count remains same.  This will prolong  battery life.  If you carry on charging to 100% and reached 500 or 1000 cycles a message will appears above battery icon "consider replacing battery" or "battery not charging", and on Macbook something like "Service Required".  Sometime the battery cells are perfect but the battery still show these messages.  This is where a battery calibration tool such as NLBA Anaylizer is very helpful to reset the battery charge count by resetting the circuit. Alot of the time after resetting battery performs normal.

Here is link for the tool:  https://www.laptopu.ro/product/laptop-battery-chip-reset-repair-and-program/

If the Laptop battery is dead you can still use it via charger whereas Macbook and small portable devices such as Ipads, iPhone, tablets, etc, require a working battery otherwise  it may fail to boot. Discharging the battery to 0% reqularly will affect the battery cells and capacity will deteriorate. Leaving the battery full discharge for a long period could put the battery to sleep mode.  Sometime leaving the charger plugged in for long period wakes the battery and start charging again. Otherwise replace battery or use NLBA Anaylizer wake the battery.  Tablet batteries I have revived by injecting voltage directly into battery terminals via a bench power supply (providing correct input voltage is set on the power supply) For example, battery input voltage is 4.7vdc then power supply voltage need to be set at 4.7vdc to prevent damage. This type of work should be carried out by experienced person incase of short circuit , battery swelling or even worse explosion.

If you are storing the battery for example going on holiday, charge the battery upto 50% disconnect it from the device if possible and this should keep the battery in good condition.

 

Simple, keep the battery in the charge cycles mentioned above, calibrated and battery should last a resonable time.

Happy Computing!!!

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