TIPS on repairing LAPTOP......

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TIPS on repairing LAPTOP......

Post by hymtone on Sun Feb 19, 2012 7:49 pm

SHARE KO LANG TONG MGA ITO BASA BASA LANG AS WE ALL KNOW DAMI NA NAG SISIMULA MAG REPAIR NG LAPTOP

SANA MAKA TULONG SA INYO

Component Level Motherboard Repair (Not replacement)

1) 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?

2) Is it usually a bad capacitor?
badcaps seems to think so. What about a bad connection?

3) How do you perform the component level repair?
So you've found the bad capacitor or component, can you really solder a new one on without hurting the components around them? What's a good soldering iron for under $100?

Answers to your questions

Diagnose problem:
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 notbook motherboard:

1. make sure main system powers are ready, that is 3V and 5V.
2. switching circuit is ok, which involes IO/Keyboard controler, 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 not matter if the cap was burnt or not.
Loose connection
Mostly happen on VGA chips, south birdges and the places close to CPU. Hard to troubleshoot and need lot experiences.

How to repair?
You need specialised 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.

Troubleshooting Dead HP G6000 Motherboard

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.

Case Study 1

"Machine: HP G6000(same mainboard as V6000)

Problem: Laptop will not power up, completely dead

Di******ion: 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 adaptor ok with mainboard).

Everything ok except 10 pin, ACIN is 0V. This is incorrect, mainboard doesn’t detect there is an adaptor! 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 charging battery. Switch on with power adaptor, ok. Remove the power adaptor once switch on, battery keep the mainboard running, ok. But still can’t switch on from battery once remove the power adaptor. 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.

Case Study 2

"Machine: Acer 4600

Problem: Laptop will not power up

Di******ion: The machine wont turn on when customer bring in.

1. plug in our power supply and it shows short circuit on board, the current jump to the 5A, which is the limit of my power supply.

2. take off the mobo, drop the voltge of power supply to 5v, limit current to about 1A, plug in again and find a mos very hot.

3. replace this mos, now the short circuit fixed.

4. turn on, the current goes up to 0.3A and stopped, it should go up to 1A during booting.

5. touch cpu, not hot, no power to cpu.

6. check the cpu pwm, which is max1907a. all conditions to make it work are present, but still no power output. the ref voltege is 0. so most likely this chip gone.

7. I replace the chip and everything work fine.

For lots of unknow brand laptops, sometimes very hard to find drivers. I don't know how many people know there is a trick to install a similar driver.
Machine: TPG (can't see the model clearly)

Could not find the driver, TPG web site only point to Asus web site and doesn't give which model it clone from Asus. We can't find vga driver.

We use Everest to check what vga chip it use and find it is ATI IGP 320M U1. Download few from different web sites, all of them just give a message said could not find hardware it supports.

Finally, download a driver from fujitsu web site for the lifebook S2020(same vga chip and south bridge chip as TPG's). But still give the error message said no support hardware find.

Every device has a Device Instance ID, and windows will compare this ID with driver's INF. It will install the driver if it find a match ID and match SubSys, otherwise will give an error message.

We check the driver for S2020, find the string "PCI\VEN_1002&DEV_4336&SUBSYS_118110CF" in one of the INF file. We also find the Device ID on our machine is "PCI\VEN_1002&DEV_4336&SUBSYS_2029161F&REV_00" . Device ID is matched but just into different sub system. Replace the string in S2020's INF with our Device ID string, driver is installed correctly and no error message.

Dell inspiron 6400 with a power problem.

Laptop can't run nor charge the battery on adapter, but on battery it's run.

This is typical protection circuit problem. check the 2 mosfet just after power socket

Charging problem
C700's charging chip is 39A126, DV6000/9000's charging chip is max8724 or max8725. Check the working conditions of those chips. such as VIN, ACIN, ACOK, LDO, REF, SHDN.

Charging problem is second hardest problem on notebook repairing, the first one is signal level – everything looks ok but just no display.

usb no power
The following solution only apply that usb no power, if the usb device get power but can't be detected or can't be recognised by system, that indicates south bridge problem.

To get power for usb is very simple. use multimeter to find out which usb pin is ground, the pin on the other side will be the power. for example say pin 4 is ground so pin 1 will be the power.

connect power pin to 5v you can find on motherboard, usually a big inductor(becareful, when you measure the voltage, put battery in as well, some mobo the inductor for charging circut give you 5v if you don't put battery in but jump to battery voltage once you put in the battery, such high voltage will burn your usb devices). connect it on the different side of inductor that mosfet connect to(or should I say power out side?) so you can get smooth waveform, don't connect to the same side of mosfet(this is power in side).

Dark image on the screen , just very hard to see, a torch will show it is there though).
When we fix such problem, usually we do the following:

1. find an known good lamp or screen, plug into inverter see if its light up. if it lights up so you need to change your screen's lump.

2. if it not light up, do following:

a. check power(either 5V or 19V), enable signal(3V), brightness control(3V) are presented. (all testing by done with adaptor plug in).

b. if all those presented, then change inverter otherwise

c. need to find out which wire is power, which is enable, which is brightness people find hard in here because they don't know how to find out which is which.

Power always connect to fuse (also need to check fuse is ok). for the other two, you need to check inverter pwm's datasheet to make decision. Just start from pwm's EN and Brightness pin, trace back to connector. After you find out, make sure all these wires has normal resistance to ground, otherwise you have to cut off the wire that abnormal. Then try to find exact voltage from mobo and connect to inverter, by doing this you are not really fix the problem but bypass it. It is a easy to work around it rather than fix problem.

Q. The first step to troubleshooting is monitor the current change. usually, current reading can tell what was wrong and quite accurate. You frequently mention monitoring the current change to pinpoint the area of failure. Can you please describe this troubleshooting technique in more detail with some guidelines and numbers to look for?

A. To understand why current changing, you may need to know the basic powering states of notebook – which is called ACPI standard – S0 to S5.

S0 is full runing state, S5 is state that after you swith off laptop but with either power or battery presented. out off topic here, the S5 is the state after you shut down computer not the state you just plug in the power. Power button is for wake up computer from S5 and enter into S3. In ACPI standard, to switch on computers you need a signal "RSMRST". It explains why some laptops auto switch on if there is no CMOS battery, because its EC send RSMRST when power plug in. But you need push power button to switch on laptop if there is CMOS battery, because laptop remembers it is in S5 state.

Powering up a laptop can be divided into few parts, first check south bridge's gpio defination, check communcation between bios and south bridge, check system ram, power cpu, power up vga. so you can see the current goes up and down. step by step it reaches to full power.

Current changing monitor is just give you rough idea, sometimes not so accurate. let's see 2 examples:

1. a hp 530, power up but stay on 0.68A. it should go down a bit after 0.68A, and up again. The faulty mobo current change is 0.02 – 0.3 -0.68. After we see this current, we know it may have problem on SB or may be on NB but most likely is SB.

I check LPC 0 to LPC 3, no signal find. it may have problem on SB or BIOS. So I flash the BIOS before I do anything on SB. It was fixed after I reflash BIOS.

2. DV9000. Normal mobo: 0.01 – 0.3 -0.9 – 1.1 – 0.9 – 1.2 -1.45 then display. we find faulty mobo 0.01-0.3-0.9-1.1-0.9, by checking DMI Link we find there is one or two pulses. So we have an idea that it already pass memory checking, the next stage is VGA checking and active VGA output. In here, if it stop in 1.1 it most likely NB or SB problem, but if it stop in 0.9 or after, it may be the problem of VGA.

Current changing gives you an idea about where is the fault but not 100% accurate. People ask me what fault by just give me the current reading and I always say you need to give me the changing states, how many jumps that current made.

Machine will run on charger with battery removed instal the battery and it will only run on the battery not the charger
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 sametime. Laptop will detect this abnormal current and refuse to start up. Remove either one, machine can start up.

How to diagnose motherboards on a component level. What tools needed?
I find it is very hard to explain this. actually, it is very simple and can be described in two words: current and singal. read the current change during booting tells you where the machine stopped. check the singals on the different part of motherboard tells what is wrong or what is missing.

Tools are: smd rework station, bga rework station, power supply has 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.

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

How to replace the graphics card on a dell 1420, the gfx card is a nvidia 8400gs
To fix such machine, first you have to do bga reworking on the chip, then connect fan to usb power to make it spin faster and non stop. also need to cut off fan controling wire.

could short on PQ8 make gate voltage high on both mosfets?
what do i need to check to find out why voltage is 19.36v.at gate
i have tested PQ8 and PQ9.results are as follows. PQ8 is AO4407. pin 1,2,3 is 19.37v. pin 5,6,7,8 is 19.36v. pin 4 gate is 19.37v.

PQ9 is AO4407. pin 1,2,3 is 19.37v. pin 5,6,7,8 is 11-12.00v. pin 4 is 19.37v.

i have set meter on diode mode and put positive on pin 2-3 and negative on 6-7 the meter beeps and shows resistance of 0.6 ohms,then i reversed the positive – negative ,meter beeps again shows resistance of 0.6.it beeps both ways. this is PQ8.

i have done same as above with PQ9 and it shows resistance of 25kohm both ways.

Solution GATE PQ8 PQ9 Should be coneccted in the same line (trace) , if PQ8 is burn please check also PQ19 , another ao4407 are conected in the same DRAIN SOURCE , you need to remove from mobo and test in continuity or 200 Ohms scale , if you see 0 – 10 Ohms betwen drain source is burn sure , check then PQ19 . You need 19v at PQ9 pin 5,6,7,8 but if PQ8 is burn not work . PU4 ISL6251 is the charger IC.

Toshiba sattelite P200-1JV laptop.it runs on battery without any problem.
it does not run with a/c. does not charge battery.

Solution first check all mobo marks to found mobo model and if you can found the schematic , then you need to found one mosfet 8 pin sop8 that is conected directly to DC JACK , and then found the next mosfet conected with the first mosfet , when you conect AC you need this 2 mosfet open , 19volts at DRAIN SOURCE , and about 8-10volts at GATE to open , usually is controled by the IC charger circuit , maybe have a short in AC circuit side or IC charger not recognize the adaptar and no open mosfets .

Having problems whit dell xps M1530
Dont do nothing when press power button , ACAV_IN is present at Q5 Q6 (3.2V) i have DCBATOUT but 3v and 5v not present , i check DCBATOUT for U69 TPS51120 and is OK , then check VREG3 VREG5 and also work fine , but i dont have 3V/5V_EN to activate outputs , Q17 is not in mobo only pads , D16 have 0.06v at 3V/5V_EN and 3.3v at PURE_HW_SHUTDOWN# , maybe need S5_ENABLE to activate 3v and 5v ? what you think about the next step to check ? maybe some signals in KBC WPC8763L .

Solution At the moment the TPS51120 is working , use power supply to put 2.5V in D16 3V/5V_EN and the 3V 5V outputs go enable . find why S5_ENABLE and 3V/5V_EN are low .

My D505 may power on boot OK or may have following condition.
a)LED flash

b)"da.da.da....." sound.

Solution If you know the bios manufacturer, the beep code will tell you where the failure is.
So the number of beeps and the duration of each beep is a specific code from the bios to let you know what it couldn't start – like video, memory, cpu etc.
The north bridge dry joint, it is common fault of this model. BGA reworking on north bridge, and replace the north bridge if bga reworking doesn't work.

It's a Toshiba Satellite A205-SP4077, Core 2 Duo. While replacing cracked LCD tried several panels with no success.
Then noticed LVDS RX2- signal from motherboard is missing.

Solution The north bridge dry joint, it is common fault of this model. BGA reworking on north bridge, and replace the north bridge if bga reworking doesn't work.

A friend has an Acer, one of the alphabetic keytops has come off. It doesn't appear to be broken, but I'm having trouble clipping it back on. It's a weird double hinge, something like a Thinkpad, which I've fixed before (easily). Any insight into mechanical aspects of keyboards?
Solution First, put the retainer(or what you said "hinge") onto the keyboard base, then put the key on the top, slightly press down and lock the key on the retainer.

I currently have a HP DV6000 sitting in front of me with several rows of black/grey lines over the screen. Is it worth trying to fix yourself or should I just send it in for a warranty repair
Solution Send for warranty if it is still in warranty. To complete solve this problem, you need to replace Nvidia chip which was made after 30th week of 08.

A friend opened up his notebook to give it a clean but when he put it back together the bios is not finding the hard drive Solution Make sure you plug hard disk firmly.

It could be the problem of south bridge, the south bridge controls hdd. I have seen many times that clean cpu fan and end up with non working laptop.

I have a problem with a toshiba tecra M9 I bought the notebook on ebay. The seller said it was dropped, worked for a few days and then died.
Solution The common problem of this model is vga chip dry joint. check the hdd light flashing or not, it should be the vga if it flashes.

Note: The hardest repair laptop is dropped one, even harder than watering. The south bridge, north bridge and vga chip all could be dry joint. To fix such machine, I always resolder those big chips, sometimes it works and sometimes it is not. There is no good way to fix such machines, just simply take the chance.

Laptop has crashed and when you boot, the screen is split so there are 2 identicle screens vertically (1 above the other). It wont boot normally or last good config but will boot safely with networking but if it boots like this, wouldnt that suggest a hardware/bios issue.

Do you think if I heat up the VGA chip (or SB or NB) then the solder will melt and get fixed?

If so, what should I use to heat it up?
Solution I am not suggest you do that unless you have bga rework station. The temperature control must be very strickly. But if you want to take the chance, I suggest you use 2 hot air guns, one from top, one from buttom. Set the top temperature to 350, set the buttom to 300 and blow it about 10 min.

In the case you want to go ahead with such project. you must firmly fix both air guns and motherboard, not let them move when you blow the hot air. Use a little stick to touch the capacitors or resistors around the big chips, keep blowing about 5 min when the solder on small components reflowed. Don't forget to apply flux between big chips and pcb board. don't set buttom temperature too high, otherwise the components on the buttom may fall off. Good luck.

To be honest with you, I have less than 10% successful rate for dropped machines even I have a bga rework station. The watering boards I have more than 70% successful rate.

I have an issues with my girlfriend's old Acer Travelmate 3260 (bought 2007), the power input pin has broken and it no longer gets any power to the system. This gradually happened over time with it getting looser and not charging properly.
Do you have the schematic for this model and also do you have instruction on how to replace the power socket, plus where to buy the component from?

Solution You don't really need schematic for such repair job. The DC jack you can find on ebay, I think someone in uk sell all type of jack. you also can attach a cable if you couldn't find such jack, and such connector can be easily found in online.

Dual screen problems
Solution First, I don't think it is a good idea to use dual screens on laptop, you put extra loading onto the vga chip.

Second, the external monitor flicking means vga card try to setup the display mode and resolution on the monitor. It will be stable once it set the display mode and resolution.

Vga overheating
Solution There is overload to vga chip.

I still remember that back about 3 years ago I saw people modified their IBM Thinkpad, they use QXGA(resolution is 2048x1536) to replace original sxga(1400x900). The result of doing this is vga chip get overheat and kill machine fast, usually not over one year. But for the people can do such modify is no problem to fix their motherboard – resolder the vga chip, or replace vga chip.

The more calculation of vga chip carried, the more heat it generated. Think about how many calculation jobs that vga chip has to do in your situation, not only the internal lcd, but also the external lcd. Much more than those people change lcd from sxga to qxga.

DV6000 laptop power switch problem
Solution The power switch from DV9000 is same as DV6000. There is other way to switch on your machine and you will know if is ribbon cable problem or m/b problem. It is handy if you have a multimeter. The switches of most laptop ( include dv6000) are just pull a voltage to the ground and send a signal to EC (most people call it keyboard controller). So check your ribbon cable connector on the motherboard, on the 3rd pin( can't remember from left or right, but it doesn't matter you can try both) it should have 3.3V, short this pin to the ground and your machine should power up. Don't worry you wouldn't damage anything even you short every pin on the connector to the ground.

Q. I have a Gateway P-6825 Laptop that has no backlight on LCD. I have bought 2 inverters 2 LCD cables I have tons of screens no matter what I get no backlight. It works perfect on external monitor and you can see it come on the LCD but the screen will not light up.
Also what is the normal input power to the inverter as well.

A. Inverter board input power sometimes is Vin or B+, close to AC adapter voltage. You may check if is there a fuse in the LCD connector path. I'd suggest you search for the inverter IC datasheet. For inverters using OZ960 there is an input called ENA which must be 3.3V for enable inverter and another called DIM which is 3V for full brightness. Hope this helps.

Q.I have a Toshiba Satellite Pro A300, just tried to use the dvd rom and it's not working, it won't acknowledge any dvd's, It won't even open, last time I used the dvd rom several months ago everything worked fine and the notebook has not been moved,

A. If the dvd drive it's ok (u should test it in another laptop), it's for sure a chipset problem (the chip that controlls the drive also, it's the intel ICH8M the U33A on the schematic/board).I will exclude a connection port problem if the laptop hasn't fallen or something like that.If drive is ok, try a reflow of that chip, should solve your problem.

Q.Is a Toshiba Satellite L355-D-S7901, motherboard 6050A2175001-MB-A02, after POST starts to beep continously like a stuck key. I've tried even with bare motherboard (no keyboard connected). Will appreciate any idea.

A. check capcitors that keyboard connected, or check keyboard controller.

How to check sony protection circuits

SONY VGN-NS11S MBX-195 M790 Rev 1.1 1P-0087J04-8011 PCG-7141M ,

Sony's protection circuits are hard to troubleshoot. It is involed too many components. About mbx-165 protection circuits:

1. Power pass PF1 becomes DC_IN, at this point, Max1909 start to work. ACIN, DCIN high, LDO 5V, REF 2V(must have, can't remember exactly voltage). Max1909_PDS low to drive PQ25 (don't know exactly voltage, but lower than DC_IN).

2. PQ25 convert DC_IN to DC_IN_MOS. Here comes the hardest to troubleshoot of sony protection circuit.

PQ26's gate must be low and it was a signal call DC_IN_G1. So where this DC_IN_G1 from? In normal situation, it max1909_pds through a resistor. Now, you have 19V of this signal that is abnormal.

we check it by few steps:

1. check pc3, is it short?

2. ac_off_3# is high? if it is high, check check PQ31, PQ20, PR116, PR119, PR120.

3. ac_off_3# is low? check the ac_off_3# signal, many components involved: DC_IN part from PD2 to AC_OFF_3#. From input of PU13 (2nd pin, max1909_LDO) to PQ24A, PQ59, PQ24B.

I hate sony's protection circuit, too many troubles. Last time I fix one of such problem on sony mobo is PD2 leaking, spend me almost 5-6 hours. And solution of it? Just remove the PD2, which means it does not matter if there is PD2 or not the mobo still working. Extra protection means extra troubles and faults.

Q. uSb power problem

A. The following solution only apply that usb no power, if the usb device get power but can't be detected or can't be recognised by system, that indicates south bridge problem.

To get power for usb is very simple. use multimeter to find out which usb pin is ground, the pin on the other side will be the power. for example say pin 4 is ground so pin 1 will be the power.

connect power pin to 5v you can find on motherboard, usually a big inductor(be careful, when you measure the voltage, put battery in as well, some mobo the inductor for charging circut give you 5v if you don't put battery in but jump to battery voltage once you put in the battery, such high voltage will burn your usb devices). connect it on the different side of inductor that mosfet connect to(or should I say power out side?) so you can get smooth waveform, don't connect to the same side of mosfet(this is power in side).

Q. My Lenovo SL400 screen went dark (image there, just very hard to see, a torch will show it is there though).

A. When we fix such problem, usually we do the following:

1. find an known good lamp or screen, plug into inverter see if its light up. if it lights up so you need to change your screen's lamp.

2. if it not light up, do following:

a. check power(either 5V or 19V), enable signal(3V), brightness control(3V) are presented. (all testing be done with adaptar plug in).

b. if all those presented, then change inverter otherwise
c. need to find out which wire is power, which is enable, which is brightness. people find hard in here because they don't know how to find out which is which.

Power always connect to fuse (also need to check fuse is ok). for the other two, you need to check inverter pwm's datasheet to make decision. Just start from pwm's EN and Brightness pin, trace back to connector. After you find out, make sure all these wires has normal resistance to ground, otherwise you have to cut off the wire that abnormal. Then try to find exact voltage from mobo and connect to inverter, by doing this you are not really fix the problem but bypass it. It is a easy to work around it rather than fix problem.

Q.
1. Is there a popular model of power supply that you can recommend?

2. Do you use mini-grabbers to attach power supply to laptop or do you have a collection of common dc plugs?

3. How do you use with Dell laptops that have a third wire to identify the power supply?

A.
I just burn one power supply today, this is 4th one I have burnt in last 3 years. Lucky it was not connected to any laptop when it was burnt. It's output voltage was jump from 19V to 50V, at this voltage all laptop's power circuits will burn throuhg, I have 3 laptops burnt before.

There is no popular model as I know, but at least 5A/30V. Get a industrial grade if it possible, becuase non-industrial grade power supply can't even run a laptop for more than one hour, or you face the risk to burn your power supply – in turn it will burn the laptop. It is sufficent for repairing job but not enough for machine testing. It must have MA reading, because sometimes the reading is less than 0.01A.

I have all the collection of DC plugs, made from faulty chargers.

Ignor the 3rd pin of dell charger, it is only for PS_ID, only use for charging battery. Without this PS_ID machine still run but just can't charge. But some old dell like 5150 will not work our power supply, lucky we don't have any such machines to fix.

Q.
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?

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

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

sympton: 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.

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

A.
This is what we called protection circuit 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 sametime. 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 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.

CPU kills motherboard happen on me once, and that motherboard in turn to kill another good CPU, and this is p3 cpu.

Don't worry about cpu, 99% chance it is good.

Try to do this, find a current meter, cut off the wire of power adaptor, connect current meter to the wire. The meter must be able to read at least 0.01A.


Power Drain: A simple solution to fix Laptop problems

Ever had to wait for several minutes for your laptop to boot up?
Wish you can fix it in a few seconds, well maybe this would be helpful for you.

It can be really irritating when your laptop/netbook is slow or has choppy sound, or a noisy harddisk, or touchpad problems. There is a way to fix it easily and very safely, the best part is you dont have to spend a cent or install any software.

This simple fix is called a power drain.
It will release all the excess power that gets stored in the laptop which may have caused your computer’s hardware to malfunction. Simple hardware problems caused by excessive power supply can be solved by performing a power drain.

Just follow these steps:
Shutdown the laptop/netbook.
Unplug the AC power cord (charger) from the laptop and remove the battery. Be careful and make sure you dont break anything.
Now with the battery and charger unplugged, just press and hold the power button of your computer for 20-30 seconds.
Now release the power button, plug in the battery and turn on the computer. It should perform much better now.

Tips to increase the battery life:
Avoid charging the battery for too long.
Also avoid using the computer while the battery is being charged.
Turn off the computer when you dont use it.

This can be helpful for a Desktop computer too:
For desktop computers,take a note of the cords and where they plug into. If you dont know about this ask an experienced friend to try this.

Unplug all the cords from behind the cpu, press & hold the power button for 30 seconds. Replug all the cords and turn on the computer.

Problem: Scratched screen

Cost: 30 PESOS
Time: 5 minutes
Materials: Toothpaste, cloth, window cleaner

Replacing a screen and its inverter electronics is a tough job that can cost several hundred dollars and take hours. For an old system, it's likely not worth it. But if the display is only slightly scratched, it's a no-brainer to fix it.

After a trip to the beach on a windy day last summer, I noticed a bunch of small scratches and one big one on the display of my Intel Classmate PC netbook. The scratches annoyingly obstructed the screen's image.



My netbook had one big scratch and several small ones.

These types of scratches can be smoothed out with a dab of toothpaste (and I do mean toothpaste -- the gel varieties usually don't have the necessary abrasives) and a little elbow grease.



Gently rub toothpaste into the scratches.

Rub the toothpaste between your thumb and forefinger and it should feel slightly sandy and gritty. It's these mild abrasives that will fix the screen's problem.

Gently rub the toothpaste in a circular motion over the scratches for a few seconds (not too hard -- you could rub off the screen's surface coating).

Then wipe the screen clean with a soft cloth.



While the large scratch isn't gone completely, the smaller ones are.

Finish up by cleaning the screen with a non-ammonia-based window cleaner. My favorite is Sprayway, but there are grocery store shelves filled with these products. Look it over and if the scratches aren't gone, repeat the process.

This strategy isn't perfect. With my netbook, the toothpaste only partially removed the big scratch, but it did get rid of all the minor scratches. Plus my netbook now has a minty fresh aroma.

What do I do if my battery will not charge to 100%?

There is a common Windows bug that does not recognize a newly installed battery. To fix this problem, RIGHT click on My Computer, then click on Properties. Click on the Hardware tab, then click on Device Manager. Click the plus sign next to Batteries and delete the Microsoft AC Adapter and Microsoft ACPI-Compliant Control Method Battery items. Shut down the system. Unplug it for a minute, then plug it back in and reboot. When Windows starts, it will identify the battery and start charging it fully. If this does not fix the problem, you probably have a defective battery or a battery with incompatible firmware.
What is the best way to charge my new battery?

There are two schools of thought on this. First, charge the battery to full for about 8 hours before you use it, then discharge it fully. Do this about three times. Second, use the battery in its current state and drain fully. Then recharge for 8 hours and discharge fully again. Do this about three times
How can batteries be connected


When interconnecting batteries (cells), they must be identical in voltage and amp rating!

Batteries may be connected in series. the positive terminal of the first battery is connected to the negative terminal of the second battery; the positive terminal of the second is connected to the negative of the third, and so on. the voltage of the assembled battery is the sum of the individual batteries. The batteries are connected: + to - to + to - to + to -, etc. The capacity of the battery is unchanged.

Batteries may also be connected in parallel. The positive terminal of the first battery is connected to the positive terminal of the second battery, the positive terminal of the second is connected to the positive of the third; the negative terminal of the first battery is connected to the negative terminal of the second battery, the negative terminal of the second is connected to the negative of the third and so on. The batteries are connected: + to + to + and - to - to -. In this configuration, the capacity is the sum of the individual batteries and voltage is unchanged.

For example, (5) 6V 10AH batteries connected in series produces a battery array that is 30 Volts and 10AH. Connecting the batteries in parallel produces a battery array that is 6 Volts and 50AH. Ordinary auto batteries are designed in the same fashion. Six 2-volt cells are arranged in series to produce a 12v battery. Many Ni-Cd batteries are arranged in the
Problem de******ion:
Basic de******ion of the design:

18volts + ground comes into the dc power jack - 2 wires carry the current about 4 inches and a plastic connector splits it into 2 18volt wires and 2 ground wires - they attach to the motherboard (where I have all good connections).

Ac input has somehow fused with the battery input - and in turn disconnected itself so that the laptop believes that both the battery - and the ac input are BOTH battery.

Notes:

1 When a fully charged battery is installed laptop works perfectly

2 When battery is removed – and ac cord plugged in – laptop gives fast blinking lightening bolt (warning that the battery is too weak to be used ) – of course the battery is NOT INSTALLED – so this blink error should not be happening.

Tested:

Ac power adapter. = Good
Battery = Good
Correct voltage reaching the motherboard through the cables.

The laptop seems to think that a weak battery is attached (when NO battery is attached and the ac adaptor is plugged in)

Solution: Change the capacitor chip on the motherboard that is causing the problem.

Testing Battery Terminals
There are SIX terminals on the battery; with the battery removed the power throughput on each motherboard battery connection should change.

Battery removed on a good laptop=
1: negative
2: +3.31 volts
3: negative
4: +5.0 volts
5: +5.0 volts
6: +1.44 volts

Battery removed on DAMAGED laptop=
1: negative
2: +.77 to +.89 constantly changing voltage
3: negative
4: +1.2 to 1.30 constantly changing voltage
5: +1.15 to 1.30 constantly changing voltage
6: +4 to +7 constantly changing volts

It is obvious to me that with varying power outputs like this - all at such low numbers I can not expect this laptop to start up - So one of the parts between the ac input and where the battery input goes must have gone bad - because with the battery installed the voltages go back to normal; and of course the battery will never charge...

Battery Installed on a good laptop (same readings on damaged laptop)

1: negative
2: +2.0 volts
3: negative
4: +5.0 volts
5: +5.0 volts
6: +16.0 volts (probably changes slightly depending on the strength of the battery)

Why does the laptop battery power reduced even if i don't use it

Because of the humidity and non-insulated environment. All the batteries will be discharged naturally. It depends on the quality and newness grade. It is normal to reduce 1% power in 3-4 days.
The New Battery Isn’t Charging. What’s the Deal


1). New batteries are shipped in a discharged condition and must be charged before use. We generally recommend an overnight charge (approximately twelve hours). Refer to the user's manual for charging instructions. Rechargeable batteries should be cycled - fully charged and then fully discharged two to four times initially to allow them to reach their full capacity. (Note: it is normal for a battery to become warm to the touch during charging and discharging).

2). New batteries are hard for the device to charge; they have never been fully charged and are therefore "unformed". Sometimes the device's charger will stop charging a new battery before it is fully charged. If this happens, remove the battery from the device and then reinsert it. The charge cycle should begin again. This may happen several times during the first battery charge. Don't worry; it's perfectly normal.
The Don’ts and Do’s of Battery Use


Battery Don'ts

1. Do not short-circuit. A short-circuit may cause severe damage to the battery.


2. Do not drop, hit or otherwise abuse the batery as this may result in the exposure of the cell contents, which are corrosive.

3. Do not expose the battery to moisture or rain.

4. Keep battery away from fire or other sources of extreme heat. Do not incinerate. Exposure of battery to extreme heat may result in an explosion.


Battery Do's

1. Fully charge/discharge battery up to 4 cycles before achieving full capacity of a new battery.


2. Fully discharge and then fully charge the battery every two to three weeks for battery conditions.

3. Run the device under the battery's power until it shuts down or until you get a low battery warning. Then recharge the battery as instructed in the user's manual.

4. Remove from the device and stored in a cool, dry, clean place if the battery will not be in use for a month or longer.

5. Recharge the battery after a storage period.

6. Ensure maximum performance of the battery by optimizing the device's power management features. Refer to the manual for further instructions.


SANA NAKA TULONG SA INYO ITONG MGA TO

MGA BOSS PAKI UP NA LANG PARA MABASA NG IBA NA GUSTONG MA22

MARAMING SALAMAT PO

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Re: TIPS on repairing LAPTOP......

Post by ultrasonic™ on Mon Feb 20, 2012 5:28 pm



+1 ka sa akin to open up this kind of thread (^_^

dagdag lng aku ng kunti.. pg hardware issues ang problem kailngan maingat sa pagbaklas ng unit... if di kabisado ang pgbabaklas hanap muna ng free service manual sa internet...

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Re: TIPS on repairing LAPTOP......

Post by Hertz on Mon Jun 04, 2012 12:39 pm


lagi ka bang nakakasira sir ? Razz

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Re: TIPS on repairing LAPTOP......

Post by ultrasonic™ on Sat Sep 15, 2012 7:26 pm


nyahahaha bueng (^_^

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Re: TIPS on repairing LAPTOP......

Post by DJFEL on Sun Dec 02, 2012 2:59 pm

nice one...

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Re: TIPS on repairing LAPTOP......

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