!!! Find Answers to Your Laptop Motherboard

Technical Questions !!!

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Component Level Motherboard Repair (Not Replacement)

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Problem:
How do you diagnose motherboards on a component level. What tools needed?

Solution: I find it is very hard to explain this. actually, it is very simple and can be described in two words: current and signal. read the current change during booting tells you where the machine stopped. check the signals on the different part of motherboard tells what is wrong or what may be missing.

Tools are: smd rework station, bga rework station, power supply with current meter. all the rest tools you can find in any radio tv repair shop. of course all the datasheets for the components, especially the schematic diagram, you will find it much difficult without it.

Problem:

What are common faults on motherboards?
Do certain components fail? Is there a trend as to which parts fail quite often?

Solution:

Different maker/model has different common fault. Toshiba S1 is vga chip, and can't be repaired(well, almost can't be repaired because the pcb quality is not very good so successful rate is very low).
HP DV2000, 6000, 9000, Compaq v3000, v6000, dell 1210, all those use nvidia chips have problem on vga chip or north bridge. easy to repair but have to make fan keep spinning after repaired, otherwise will break down in 1 or 2 week again.

hp nx5000, cpu pwm chip dry joint. acer 290, cpu pwm dry joint.
hp dv1000, Compaq m2000 protection circuit easy to blow up.
ibm t40 vga dry joint problem.
These are just few of them. every machine has its own common fault. but dry joint is the common problem for all machines. Motherboard repair is not as difficult as people thought, i think much easier than repair a tv.

Problem:

Dell 1525 Inspiron that does not recognize the installed battery this system will not charge the battery.

Solution:

Charging battery in Dell laptop involves two major chips: EC(or someone call it super IO), PWM chip for battery charging. BIOS has no part of charging. Battery communicate with EC through SMB(system management bus??) and EC controls charging PWM. Fix charging problem is very hard in laptop repair, you must fully understand schematics, where all the signals come from and where to go.
Today's laptops are less and less with programmed EC, Dell 1525 has no programmed EC so it can be replaced with same model.

Problem:

How i fix a DV6 with power problem. The problem of machine is it cannot power up at all.

Solution:

Doing routine check:
1. system power: 3V, 5V all presented - ok
2. NBSWON signal: 3.3V presented - ok
3. press power button, NBSWON pull down to 0V, ok
4. check DNBSWON while press power button, no response. - problem.
in here I made a mistake, I didn't pay attention of the voltage of DNBSWON, this mistake waste me the next few days time. It should be 3.3V, but only about 1V.

Change EC as usual, because I thought the EC has problem. Then the big trouble comes - it auto power up once I plug in the power but stop in 0.04A current. Check and find no S5_ON signal, which indicate south bridge has problem, so change south bridge. But still same problem and still no S5_ON. I find that the EC I change is kb3926A rather than kb3926C. In most case, this is no problem but in very rare occasion...
So I find a 3926C and put on. Now the motherboard is back to the same problem where I first start to check! So I change a wrong EC and this time I change a correct one, and also EC has no problem!

Because EC will start to read bios once the power plug in(not as people think, once you press power button). I check BIOS chip, BIOS_CS should have a continue wave form but it just one straight line. BIOS chip is faulty, I replace the BIOS chip and it works perfect.

Problem:

How do you diagnose the exact component failure?

Obviously, a burn mark is a dead give away, but what if there are no visual signs? Do you poke around with a multi-meter?

With what voltage settings and how do you know what to look for?
Is it usually a bad capacitor?
What about a bad connection?
How do you perform the component level repair?


Solution: [Answer to all your above questions]

This is the hardest part in notebook repair. Basically, we measure voltages on motherboard and there are few power supply range from 1V to 12V on the motherboard. For example, north bridge needs 1.05V, 1.2V, 1.5V, 1.8V, 2.5V, depends on model of north bridge.

We also measure all sort of signals, such as PCIRST, CPURST, CLK. We measure the resistances of each AD line from north bridge to CPU/RAM.

We watch the current changing patterns to get rough idea where is the problem.

There are some simple steps to follow when checking a notebook motherboard:

1. make sure main system powers are ready, that is 3V and 5V.
2. switching circuit is ok, which involves IO/Keyboard controller, south bridge
3. power sequence is ok, which you can see the current jump up and down for few times.
4. all the necessary signals are not missing.

About Bad Cap:

It happens but only about 10% in those motherboards need to repair, and it is the easiest fault to repair no matter if the cap was burnt or not.

Loose connection:

Mostly happen on VGA chips, south bridges and the places close to CPU. Hard to troubleshoot and need lot of experiences.


How to repair?:

You need specialized tools. I have DC power supply which can display current change and set to different voltage and current output. You need Really nice soldering station, SMD rework station, BGA rework station, etc. I also have more than thousand schematic diagrams, all together about 10GB and you could not find anywhere in the net.

I have seen the video in youTub teach people how to fix VGA problem, and I guess you only have 30% chance if you follow it. My BGA rework station tutorial can perform up to 95% successful rate.

Case Study

"Machine: HP G6000(same mainboard as V6000)
Problem: Laptop will not power up, completely dead

Description: The machine has been water damaged. It does not have system standby power, which are 3V and 5V.

Finding The Fault:

Check Max8724(the battery charging chip) first, because to make system has standby power this chip must work correctly. This is a 28 pin chip, we only need to test 1, 2, 4, 8, 10, 11 pin. They are VIN(main power for chip), LDO(provide 3.3V for chip itself in order to set REF voltage, also provide signal to drive 2 MOS to charge battery), REF(set reference voltage of the chip), SHDN#(enable/disable chip, a switch), ACIN(indicate the power supply has plugged in), ACOK#(power adapter ok with mainboard).

Everything ok except 10 pin, ACIN is 0V. This is incorrect, mainboard doesn’t detect there is an adapter! Trace it backward and find it is very simple – mainboard use 2 resistors to pull the input voltage(19V, directly from dc socket) down to about 4V, so test the first resistor and find it opened. Change it and 3V/5V power come up and mainboard be able to switch on.

Then the trouble start when I try to charge the battery. The charging current never go beyond 0.15A and after 10 seconds the charging light start to flashing. Also can’t switch on from battery. First, change Max8724, still same problem. Next check all the resistors around max8724 and change it if it has any sign of watering, still no good. Then change KB3926(EC/KBC, chip monitors the statue of battery), still same.

Decide to check MBDATA and MBCLCK, 2 signals that send battery information from battery to KB3926 before I give up. I find the MBDATA is short!

Finally, find there are 2 pins stick together on CN10(the connector of multimedia switch board). Fix it and it start to charge battery. Switch on with power adapter, ok. Remove the power adapter once switch on, battery keep the mainboard running, ok. But still can’t switch on from battery once remove the power adapter. Think, think, do I miss something here or there? Oh, the CMOS battery not installed, put the CMOS battery back and everything work perfectly. The battery part of troubleshooting takes me about 3 hours.

Remember, system may not run if you don’t have CMOS battery or CMOS battery is low for some AMD cpu mainboard.

Problem:

1. Is there a "generic" current profile for laptops or does each laptop have it's own unique current profile?

2. In your example for DV9000, you say "0.01 - 0.3 -0.9 - 1.1 - 0.9 -1.2 -1.45 then display" Can you explain what happens at each current change state?

3. Do you need a power supply that logs the current or does it change slow enough to visually monitor the different current states?

4. If a laptop gets power but no video, how do you isolate the failure between northbridge,southbridge,SIO,bios?

Solution:

1. Every laptop has its unique current profile. But although the reading is different, the up and down (jumping) are similar.

2. The dv9000's current reading may not very accurate, I suggest you first move the ram away and see how the current changing, then put back the ram and check it again.

3. not very fast, your eyes can catch the changes.

4. this is a big question, may need a full text book to explain it. The simple answer for this question: a. current reading, b. LPC wave, c.SMB wave. we have explain the current reading before. LPC waves are measured on EC, if you can't find LPC wave, that means no communication between EC and SB, PLTRST present or not, if is not then SB problem, etc. SMB waves are measured on ram slot, communication between ram and northbridge, H_RESET present or not, if it is not then NB. There are also so many signals need to check, can't remember what are them now.

I think the hardest fault for beginner is why the laptop not power up, not the faults after it powers up.

lets see the example how we troubleshoot a non-powering machine,:

Model:acer 5737

EC: kbc926

symptom: can't power up

checked: 3ALW, 5ALW presented

1. check the power button has power or not, press it to see if pull down the voltage.

2. check kbc926's 32 pin, which is on/off see the signal received.

3. EC_VCCA is high?

4. check EC_RSMRST is high?

5. LID_SW# is high?

6. ACIN is high?

7. EC_CRY is correct?(32.76Khz)

8. South bridge crystal correct( which is X4, also 32.76KHz)

9. PBTN_OUT pull low when you press power button?

if all above have no problem, consider the south bridge fault. for this machine, there is a single bridge - south bridge/north bridge/vga combined. North bridge's functions are mostly taken over by CPU.

Problem:

This laptop will run on ac charger it will NOT run on full charged battery.

Solution:

This is what we called circuit protection fault.

Looks like discharging has problem. When discharging mosfet has problem, or the Gate voltage not correct, the 18V of main power will directly go to battery.

The current will be very large when you have short discharging mosfet, if you plug charger in and have battery installed at same time. Laptop will detect this abnormal current and refuse to start up. Remove either one, machine can start up.

Please Note:

The first step to troubleshooting is to monitor the current change. Usually, current reading can tell what was wrong and quite accurate.

CPU faulty is rarely happened. I only see no more than 5 to 8 cpu faulty during 10 years.

Things that are likely worth solving:

Bad capacitors. Decently common and the parts only cost a few cents.
Most of the ICs on board... 4-20 pin jobbies such as the power ic do fail and are swappable for less than a buck or so

Blown fuses. Easy to diagnose easy to replace. This is a definite.

Any and all damaged jacks. Power and audio being the most commonly broken.

Resistors. easy to find easy to replace. cost is in pennies.

Transistors and diodes can be more problematic to diagnose and fix but they too are cheap and swappable with just a soldering iron.

Obviously you can swap cpus so you should be able to diagnose that as well.

"A Practical friendly guide to repairing Laptops. through easy-to-understand language, detailed problems & solution tutorials. The book emphasizes a deep understanding of how a Laptop works How to diagnose and repair problems; it concentrates on practical, hands-on solutions that can be implemented right away."

"A unique approach to troubleshooting Laptop hardware problems. creates a expert system for diagnosing component failure and identifying conflicts. The diagnostic steps at the core of this book are intended for the intermediate to advanced hobbyist, or the beginning technician".

"Following a structured approach to troubleshooting hardware reduces the false diagnoses and parts wastage typical of the inexperienced technician. Problems include: Power Supply Failure, Video Failure, CPU, RAM Failure, Motherboard, IDE Drive Failure, CD or DVD Recording Problem, Modem Failure, Sound Failure, Network Failure, Peripheral Failure,Conflict Resolution."

"Focusing mainly on installing and troubleshooting hardware, the book also provides solutions to common operating system-related problems. Regardless of your level of experience, this is the perfect resource for anyone who owns a laptop, wants to repair a Laptop or is considering a career in the Laptop repair business" "The author goes where no Laptop book author has gone before right past all the hidden screws, and the fear factor to produce a real owner's manual that every laptop owner should have on his desk."

Course Content

SECTION - A

You'll discover how to troubleshoot & repair ??

• Dead Systems
• No display
• Dim display
• Freezing System
• System getting hung
• Keyboard control section problem
• Memory control section problem
• Audio not working
• USB port not working
• Serial port not working
• Ps2 port not working
• CD Drive control section problem
• Hard disk control section problem
• Battery not charging
• D C pin problem
• Soldering & De-soldering of Motherboard Ics, Transistors, Diode, Fuse, Capasitors, VGA Chips ETC....

The Best Way To Take A Laptop Apart

• How to remove Laptop motherboard
• Solving Laptop Power Problems
• Soldering
• How To Handle Liquid Problems Like Spilling water In Your Laptop
• Handling Laptop Keyboard Issues
• How You Deal With Overheating Laptops
• Fixing Keyboard Problems
• Fixing Touchpad Problems
• Replacing Broken Laptop Screens
• Replacing Memory/Data Components

How To Fit/Install Laptop Hard Drives

You'll discover....

• What you need to know about hard drive installation.
• Example Hard Drives.
• How To Partition & Format the New Hard Drive.
• What to do if You Can't Boot The System.
• Hard Disk = Laptop Hard Drive Motherboard Circuit Swap,
• Data Recovery,
• Head & Platter Swap,
• Disassemble & Re-Assemble a Hard Disk Drive
• Recovering Laptop Hard Drive Files With A USB Shell

Using our laptop repair guides, you'll have the knowledge to

• Identify ALL the parts in a Laptop.
• Fit laptop screens.
• Fit laptop keyboards.
• Fit memory into ANY laptop.
• Fit hard drives into ANY laptop.
• Clean a laptop keyboard to an 'as new' condition. This little-known technique can make you a ton of money alone.
• How and where to buy laptops cheaply and sell them for a healthy profit.
• Which laptops to buy and which to stay away from.
• AC/DC Power adapter
• Battery
• wireless network cards
• motherboard
• CPU
• Hard drive
• LCD screen
• Screen backlight lamp
• Screen inverter board
• LCD screen cable
• Display hinges
• Keyboard
• CD/DVD-RW
• Memory
• Audio board
• Web camera
• Cooling fan
• CMOS battery

Laptop Exploding Diagrams

This part contains diagrams and the part numbers. You'll use this to see where the parts fit together. Other than physically taking a laptop apart, this is the only way to see how the bits and pieces fit together. There are other information sections including pictures of components and the specifications of laptops. This is useful knowledge to have as you'll know exactly what's in a laptop before buying or repairing a particular model. Where else can you find all this information? The answer is?.. nowhere!

SECTION - B

Motherboard Component Overview

• Common Problem Of Different Motherboards
• Steps to Troubleshooting Laptop Motherboard Problems
• How to fix G4 Aple ibook motherboard with chip problem
• Fixing dead motherboard power problem

• 5 Steps to Hacking Dell D600 Bios Password
• 10 Steps to Fix Laptop Gpu problem using Rework Station or Heat Gun
  
• How To Fix Failed Nvidia Chip
• How I installed external Bluetooth adapter inside a laptop
• How to test a laptop or a desktop computer memory
• Top 10 Things to Consider When Selecting a Digitizer Oscilloscope
• Fixing hardware problems without taking apart the Laptop
• Laptop Lcd Image see what goes on behind the Screen
• Bypassing Windows 7 Logon Password In 3 Steps

Laptop sound, Ehternet Vga, usb, IC chip identifications

• IC Chip Soldering & Desoldering
• Latest Chip Level Tools & Gadgets
• Basic Electronics Soldering & Desoldering Guide
• How to Solder
• SMD Soldering Guide
• Surface Mount Soldering Tutorials
• Getting IC chip X onto board Y
• Trying to reworking with an iron
• Wonderful hot-air rework
• Green wire fixes
• Sneaky tricks for soldering leadless ICs
• How does hot air rework actually work?
• Checking Voltage and Short Circuits with Multimeter
• Testing for Backlight or Inverter Failure
• Testing A CCFL LCD Backlight Tube
• Overheating - Cleaning Fans and Troubleshooting Hot CPU Failure

General System Component Troubleshooting

• Troubleshooting Ac Adapter/Power Problems
• Backlight lamp
• Overheating system
• Display hinges
• Hard drive
• Laptop keyboard
• Laptop makes noise
• Laptop runs slow
• Troubleshooting Lcd screens
• Liquid damage
• Laptop Battery Troubleshooting
• Memory Troubleshooting
• Network port
• DVD/Optical Drives testing and troubleshooting
• Power jack
• Troubleshooting CPU/Processor
• Screen inveter
• Startup problems
• USB ports
• Video Card
• Video cable
• Wireless connection

All About Bios Password Removal

• 5 Steps to Hacking Dell D600 Bios Password
• The Bios chip Laptop BIOS Recovery
• Laptop Bios Passsword Shorting Method
• How to short the EEPROM Bios Chip on a Dell latitude d610
• Different Ways of Removing Toshiba Bios Password
• How to break Administrators password in windows xp
• Bios Flashing & Update

Miscellaneous Repairs

• Battery = How to replace battery cells inside laptop battery
• Sound = Soldering tiny sound ic chips in a Laptop motherboard
• Wifi Card = Soldering wireless card in an old Laptop motherboard
• Use Of Debug Card Post Error & Code
• Top 15 Ways to Extend Your Laptop Battery
• Latest Tools & Gadgets For Laptop Repairs
• Power On Detail Step with timing
• How to build a computer desktop
• Home Networking for first timers
  
• System Component Troubleshooting
• Troubleshooting Desktop Motherboard
• Troubleshooting Network Problems
  

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Networking: A Beginner's Guide

How to Fix Your Desktop Motherboard capacitor problems for $15

• Solder/De-solder Capacitor From Your Motherboard
• When a Motherboard Fails
• Capacitors - Mysterious Creatures
• When Capacitors Spring Leaks
• How To Recognize Flawed Capacitors
• How To Buy Substitute Low-ESR Capacitors
• Getting Started!
• De-Soldering Capacitors
• Drilling the motherboard
• Installing New Capacitors
• Everything You Need to Know About The Motherboard Voltage Regulator Circuit
  

Consider these advantages of becoming a laptop repair specialist...

• All your income is earned from home.
• Can be run by anyone.
• Free ongoing help.
• Market and expanding every day.
• Recession proof.
• Part-time for full-time money.
• You can be employed.
• You can be unemployed.
• Retired.
• Want to escape the 9 - 5 grind.

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