Thursday, December 29, 2011

Dell Inspiron 14R Spill


This Dell 14R had a water/coffee spill and blew some parts and pads
from the laptop 
motherboard.
This image shows the resistor PR12 after removed from board. Shown here
before cleaning


This image shows how it should look, and the original view.
This image shows how the repair had to be done.  Part of the pad was still visible, and the hole pad had enamel
removed to allow connectivity to the pad and trace.











DV7 Power On By Pass - TIP

The DV6000 and DV9000 series has a bypass jumper that you can short to turn on the unit without having to connect the power on button.

Now the DV7 also has a method also.  this way you don't have to disconnect from the frame and makes it prone to breakage or scratching the plastic.

Toshiba L455D - Powers On Then Off

Toshiba L455D Blink On then Off Light.
Power light functions normally. Charge light functions normally.
Does not run. Does not post.



Turns on then shuts off. The unit powers on then after a few seconds- shuts off.

This is was caused by a shorted MOSFET PQ10 that exhibited a full short 0Ω Since they were in a pair formation, both were replaced so the current level would be balanced.  The cost is so low, that it was not a consideration. Two AO4466 replaced with two AO4468 mosfets which were available.  AO4468 is out of production, but were found on an HP DV6000 near the Maxim [MAX8734/PU10] quad output power distribution chip.             (PQ31/PQ32 on DV6k)



The coil PL3 was cracked in half, was not exactly sure if the coil would be defective, but the nature of coils is to push current within the electromagnetic field, so if the field is open the electrons may not go forward, tools did not allow the ability to verify. So it was replaced. 


(When in doubt, replace)


Please No Questions regarding this repair- They won't be answered
It was simply found by finding the shorted MOSFET. This is only a reporting blog for other to have an idea where to find the problem, not to fix it for them.  Use logic in following the electrical path.  You can not learn if you are always shown the answers.




Note: No Video issues on this model is caused by the nVidia GPU, not this area. This is the power-in section. Do not reflow the whole GPU at one time, because it not anchored by epoxy. Do half, allow time to cool, then other half.

Monday, December 19, 2011

DV5-2155dx - No Video, Blinking lights on topside

I will only report how I fixed it, not answer specifics related to why/how/what or "where can I get parts" questions, because I simply don't have the time to reply to the requests.

This DV5 came in with no video display.

The problem was a coil L6002 to the right of the GPU shield.

The coil and/or pad cannot handle the 'bounce' current that flows through. Taking the coil out of the circuit path eliminates that problem.  Small inset image shows where the coil was and the old path of the circuit.
Larger View Shows coil location 

Sunday, June 12, 2011

Up Late

Up late trying to make sure everything works, buttons, answering questions that may have been missed. And printing postal addresses. After that last hectic week...

Wednesday, June 1, 2011

Sometimes it's something else

Earlier today I got my hands on an older Compaq M2000.  It was dead, no lights no anything. So checking the board (which is the same as the V2000 and the DV1000) . The front end MOSFET next to the power jack had bubbling on the surface (probably from overheating) And it was the wrong chip!? It was a SI4425 which has a lower current rating.  So I replaced it with the AO4413/FDS6679 series and tested again.  This time the charge light was on when the battery inserted. This told me that at least the unit was getting power. Then I remembered the common problem with caps on those models, so I started checking the caps. Sure enough I found the shorted cap on the bottom side near the rear of the DVD drive connector. OK replace that and turn on.

Everything lights up, except the screen. No display on external. Hmmm - checking the GPU accidentally by touching it was !!HOT!! Used the crayon test, it made a small wax puddle on the chip. This GPU was definitely shorted.  When angling the board and viewing, I noticed the GPU was not level. Rear solderballs were not touching board, but the front solderball were. There was no level gap around the GPU.  So this came to a decision to set it aside and work on it later, or attempt leveling GPU.

I placed it aside and chose to make that a project because it would need a jig to level the GPU while hot, and not contact (nor slide) resistors on the top side. As well as raising the smashed side.While holding the GPU down onto the jig. Strange device it would be. But to fix a $66 mobo? Reballing is an option but not worth the money, time and effort right now.

Thursday, May 19, 2011

Toshiba A75 - No picture on screen.

TOSHIBA A75 series are workhorses they will run and run.  The only problems I have experienced with this model  that is fairly common is the DC Jack fails, Overheating and onboard memory failure.

Since onboard memory can cause the above symptom, that was on of the first things I tested. The memory turns out to be fine. Opening the unit I see that there had been a previous spill that had dried and and was on some important VLSI chips. The next step was to closely inspect the spots where the spill was and visually determine if it could be the cause of failure.  This depends on whether it was on any PCI or video subsystems.  As it turns out it was on the PCI subsystem.

Tuesday, May 10, 2011

Explanation of Terms

Some of the terms used by techs and myself:


Dead:
Means No Power, No Lights, No Charge Light.

  Check DC Jack, test with known good battery


No Power/No Lights:
The unit will work from charged battery, but not from AC. Some light may be on.

  Check DC Jack.
When you move the charge plug with battery installed, the charge light may come on intermittently. This is caused by a cold solder joint on the DC Jack, or bad contact inside the jack. 


No Power/With Lights:
If you hold the plug at an angle, the unit will come on, but letting go of plug it shuts down.
  Check DC Jack


Will Not Charge Battery:
Unit runs when plugged in, but will not charge battery. Or the battery only last 15min after charging all day.
   Check Adapter - Generic or Wrong Amperage
Example -If you are using a 65w charger and trying to charge a DV9000 the battery will never fill up to it's maximum.
Volts x Amps = Watts   18.5v x 3.47a = 64w  and  18.5v  x 4.47a = 90w


Loops:
Posts and starts to run, then reboots.
   Suspect CMOS battery
   BIOS settings.


Lights Flash:
Lights on panel flash when I press the power button:
   Suspect dead/near dead battery.
      Check DC Jack
      Check Charge Adapter


Blue Screen of Death [BSOD]
Very common issue with hardware changes or failure, wrong drivers
   Start laptop, continue to press F8 until you get a Start Up Menu
      Disable Auto Restart 
         Restart in Safe Mode - Disable all items in Startup until you take to shop
            Or uncheck all unknown/unverified software
You can also remove or disable unused items in System Hardware, modem, network cards and reboot until culprit is found.
        
Those are just some of the symptoms that you may read on this site.











Some questions that were asked.

A few individuals have asked questions direct, and I wish to clarify some items.  It is best when you post on the blog that way it can also answer several hundred other readers questions.


Question  1: 
How do you check the (brown) ceramic caps.
Answer: 
Simple, I use a standard Ohm meter in the Resistance mode.  Since the biggest problems with caps when they fail is the become either a direct short, or they will never store capacitance (open).  The meter reads in the ohm mode by sending a small amount of electricity through resistors and report the difference in Ohms. Test with leads RED on one side and Black on the other.  One direction will give you a high resistance ~2000Ω and then reverse the leads on the meter and the other direction should give you Infinity. This is an OK capacitor. If you have a very low resistance or 0 (zero) Ohms, the cap is shorted.


Why?:  I started small just repairing for friends and family, after a number of common repairs I saw the need for a shop, so when I opened the shop I was looking at the prices of equipment (oscilloscopes, digital probes, professional hot air guns, and all the high tech test hardware) and the prices were too high for the amount of work I was doing. So as I grew, I got comfortable with what I had, and never changed.  If it works why change it?.  The success rate would could not be improved enough to justify the high dollar purchases.



Question 2: What are the soldering tools you use.Answer:  Ordinary hobby tools for the most part.  The soldering pencil is a 40w medium tip Weller type with base.

Then there is a soldering station that was purchased from Radio Shack with a small pencil tip, for the very small parts.
The key to a good solder joint is heat management, and flux.  When you are soldering large items, you should have a larger tip. Flux also assists in distributing heat as well as removing oxidation from the solder pads.  



The desoldering iron is a simple Radio Shack that cost about $12. Though it should be cleaned often, unplugged when not used. (the tips don't last long)




A scope would be nice (any donations?)  just kidding.


Other Tools do include a combination Hot Air and Soldering station (collecting dust) I just use it when I get into tight situations or the need for speed or controlled heat arises.

Monday, May 9, 2011

DV9000- Turns on- Shuts off

Symptom 1:  Unit runs for a while then turns off
Symptom 2:  Unit turns on, turns off immediately


This unit arrives after another tech had attempted repairs.  Numerous screws missing from base and incorrect screws used in reassembly.  Complete tear-down and disassembly.


After powering the unit up, I noticed that the heat sink copper was discolored [darkened] which is a sign of high heat.  Upon close inspection I noticed a kink in the heatshrink material covering the wires for the fan wires, so I strip back a portion of the insulation and the red wire was broken, and the black wire was only 2 strands. Yellow and White wires were OK.  Rather than replacing the fan (which is in short supply, and costly) I repaired the broken wires with solder and insulating them so that they would not short each other or the frame of the HS fan, which is negative ground.


Screw also missing on the exterior frame that holds the heatsink downward onto the base, this screw is important because it also keeps the heatsink pressed against the GPU allowing for the heat to be pulled away from the chip to be vented out from the unit.  This unit was also upgraded to the modified custom copper shim to further assist in heat reduction.


Reason of varying symptoms:
This model may not require the fan to reply back to P.O.S.T. -so it would run, until it got too hot to continue. The ground (fans black wire) did not complete the circuit for the 'non-working' temp sensor to report that it was overheating.  The CPU core thermal sensor eventually reported overheating before the fan could, or CPU thermal sensor would shut it down to protect the CPU. Then when the unit was immediately turn back on (while still over temp) it would shut off, since no correction was made, the info was reported to CMOS and would shut off.


This test should also be in your diagnostic 'toolkit' so that you also test the fans when you have an immediate shutdown, or runs & shutdown problems in this series [DV6000/9000/F700].  Also see the specs on MAX8734 power chip so you can identify this cause, since it do have a SHUTDOWN circuit [pin 6].  


Cause: The screw had gone through the base and was smashing/pressing the wires again metal post, effecting shorting positive terminal of Fan lead coming from motherboard connector,  and broken, no power reached the fan.  The black wire [GND] was nearly broken so the fan circuit was not complete, as well as the speed (YEL) and temp sensor (WHI) circuit because there was no power reaching the fan.


The Max8734 is one of the major players in distributing voltages to sections of the motherboard. 


MAX8734AEEI+ product name
High-Efficiency, Quad-Output, Main Power-Supply Controllers for Notebook Computers

Saturday, April 23, 2011

Compaq C500 - LED's Flash Rapidly, and never posts or starts


Unit arrives with following symptoms:
Flashing LED's on the power panel, and the power LED on the front edge flashes continuously. [See video]


When I connected the DC source with the battery inserted, I thought the charge light would come on as it should regularly. Since it didn't and flashed at the same rate as the other LED's this told me what area to check. When checking the MOSFETs PQ5, PQ49, and PQ4 all of them were of the same type [FDS4435] but PQ49 had a short in both directions with meter set to DIODE mode.  This indicates the FET is shorted. So that was the first thing to replace and test again. 


When I replaced the PQ49 FET and plugged in the charger (with battery inserted) the charge light came on, as it normally should.  Upon powering the unit, it posted normally on external monitor. 


Since it was a power in/charge circuit I assumed everything else was fine and reassembled the unit.  All items work. USB/Wifi and other peripherals.  So the unit was tested with OS loaded and everything fine there, and allowed the battery to fully charge. 



Friday, April 22, 2011

Gateway laptop M-Series - Shuts off immediately [M-6750]

This Gateway M- Series  6750 arrived with the following symptoms: 

Turns on, but shuts off after about 5 sec.  The lights would flash, then shut down. Counting seven (7) flashes before shutting off. Attempting a cold reset of the BIOS/CMOS it would not complete the reset, and continue to do the same thing. 



Because it would not write the CMOS, that shows me the first area to check.  Under close inspection of the board, I notice a coil is burnt, and the number is not visible/readable. [PL20]



The burnt coil had also burned the motherboard layer under itself and would require cleaning and insulating the second layer. This was done with a small piece of mylar tape that was placed under the coil before soldering it in place. This repair was a quick repair and not making a complete mask and copper pad for the exit contact of the coil. Works and sufficiently insulates the second layer of the groundplane.


MOSFET PQ54 was also replaced simply because the cost is negligible and would be easier to replace while the unit was open rather than to reassemble and possibly have to replace anyway. The FET was  a Fairchild FDS6900AS  which is a 30V Dual N-Channel PowerTrench® SyncFET™


After replacing the coil, I partially reassembled the laptop simply enough to get power and connect the screen.  (Image blurred while holding camera)  It Works!  Reassemble and test rest of peripherals, USB, Webcam, etc...

Compaq C500 - Bad Video Memory

Compaq C500 Arrives with bad video. 


The information is displayed just not properly. External LCD also displays same thing. This is related to the video memory of the unit and not the GPU in this case. 


This will require a low temp reflow. Because video memory is often not glued to the mother board, low heat has to be used so that the chips become separated from the motherboard. If that happens it will require special equipment and higher cost to the customer.


If you unit does not have dedicated memory for video, then it would be the chip that addresses (provides the row and column information for the GPU) the video memory.   This is usually a large chip directly to the side or near the GPU. Typically on Intel models rather than AMD. 


Middle picture shown after reflow.




 Link Video showing screen issue at Youtube 
if you have issues displaying from blog.

Tuesday, April 19, 2011

Acer 17.3" Shuts off when moved or touched

Newer Acer 17" Model [7736Z-4809] laptop arrives after being repaired.  



The initial repair was a DC jack. Seems that the jack didn't last long and was sold to a reseller. Physically broken and replaced.  

After replacement, the unit would charge and run.  Minor tests completed based upon user diagnosis.  However, if the laptop was moved when on/running, it would shut off immediately, and the lights would go off. (Charge and Run lights).




 When the unit was moved or tapped at the area on the right where logo stickers are, it would shut off -everytime. Thinking it may have been a ground issue with the case, I tapped the motherboard after it was removed, and still presented the same problem.  Repeated on/off testing located the area where the open circuit was occuring.  The PCI controller chip (indicated in square).  Since this model did not use high temp glue to hold the chip to the motherboard, the best reflow method for this model would be Low Temp reflow with liquid flux instead of the petroleum based flux.



Why? Because if the chip is having issues with the solderballs too much heat would separate the chip from the board, requiring reball or motherboard replacement. A High Temp reflow would cause that problem. And there would be no way to rescue it at this shop. So that is why low-temp reflow method was used. 



A low temp reflow involves liquid flux, and heating only half the chip at one time. First the lower half, then allowing it to cool a little, then the top half.  This method assures that the chip does not become unseated, as well as preventing solder balls pooling together and shorting out. The liquid flux aids in bonding the solderballs to the motherboard as well as removing oxidation (not much at low temp).

Saturday, April 16, 2011

Dell 1545 - No Power & Shorting Power Supply

Dell Inspiron 1545 arrives with No Power, No Lights and short Power Supply.


This unit arrived with because the customer thought it was a DC Jack repair because it was shorting out the power supply everytime it was plugged in. So it did not matter which power supply was used it would still short out. 


My way was to simply separate the power panel board from the laptop and see if it was the laptop having a short or the small power board. When the small board was removed, the power supply would still short out.  Looking into the jack itself, and testing from POS to NEG shows no short on meter. So tracing the path from the POS terminal on the back through the on board diode showed continuity.  



Reversing the meter's leads it shows 1 Ohm. So this tells me that the diode was shorting the unit. 


Extracting the power board only took 3 screws, and not having to remove the whole motherboard made things simpler and a quick repair. Then lifting the power board and replacing the diode.
Boots after replacing diode


After power board diode was replaced. To test, I simply plugged in the power supply before putting it back into the base. This would show me if the power supply was still shorting.  It did not short again, so I re-installed the power board and turned on the unit.  It works!  


Starting the OS everything appears to be OK, except for the message that Windows did not shut down correctly the last time.  This was to be expected, but everything works fine now.  


Sunday, March 20, 2011

RE: HP GPU Video information

TARGET DATE: APR 15 ~ MAY 1st


I just came up with a solution to those that are in dire need of the video. So instead of making a 'Hollywood' masterpiece, with fancy labels and jewel cases etc.  I will be doing a single Step By Step instructional video from start to finish. 


This will  make the overall cost lower, and faster completion, as well as provide list of items needed and source for US customers. (Not many countries outside USA use 120v so the heat gun here would not work there) but the other items are readily available in most places. 


So the contents will be a simple Instructional DVD by US Mail available through Paypal so that there will be no questions about me having your credit card info and such, or the complete kit, with all the parts for a D-I-Y project. The contents will be for 1 repair, but the rest of the items (*secret stuff) will be available for multiple repairs incase someone wants to do this at a shop on a regular basis.  


If you want to pre-order the   DVD ($20USD) or the repair kit $89USD (DVD and tools included) let me know and I will create an new email address, so that all that mail will go to one place, and not confuse me with blog questions, music questions, software questions and other projects mixed in. (Yes, I am doing several projects). It will be a complete solution, not just a video of me doing it, but why I do each step.  Knowing the nature of some people it will copied and re-packaged by someone that is too lazy to come up with a better solution. So I have a limited window to sell the item.  


For HP DV series, TX series, Compaq F series Hann-Star motherboards. As well as for some Gateway, Acer, Dell and others.  After you do this once, you will be surprised at the results when all the correct steps are taken, and what to watch for that kills these motherboards. Hopefully this will correct many of the defects that are on shelves somewhere sitting.


Do not send cash or Paypal until I have it all together.


* there will be no markup on the kits- what the parts cost me will be your cost

Friday, February 18, 2011

Dell Precision M290 - Lines in Video

Currently in video preparation for posting solution of the Dell Precision M290 with lines in video. Which will be added this weekend 20 Feb.  This will be a Step-by-Step video.



  1. Diagnosis
  2. Removal
  3. Preparation
  4. Repair
  5. Cleaning
  6. Test
  7. Reinstallation



The problem is the same for nVidia. Solderballs not making contact. In this case the solderballs are located in the video memory. See other video for similar problem. 


This is a screenshot from the video.

Wednesday, February 16, 2011

Dell XPS No Video (2)

This is unit #2
Dark Blue cover
This unit arrives with a request for DC Jack repair.
the jack repaired and unit plugged in to test and shuts off immediately.  So I had to inspect inside.


Opening the unit to get to the GPU portion to begin diagnosis or repair. Because you have to remove the heatsink before the motherboard, and after removing it what I see is the 'Worst Case' scenario of how a GPU should look.  


In an effort to get video working someone put balls of solder under the heatsink to apply pressure on the manufacturers solderballs under the GPU making contact with the motherboard. Along with way too much thermal compound. Though the idea was good in principle material used does more damage. The solder not only contacted/shorted resistors and jumpers on the top of the GPU but removed a number of them (probably inside a ball of solder).  Those extra small resistors and jumper sets, clock speed and memory size information for nVidia. 
But the unit was said to have worked!?  Or so I thought.


The root cause of most XPS having no video and (using the nVidia chip) is contact oxidation. One or both, motherboard or GPU. Since the number of various manufacturers use this video chip, my guess would point to the GPU.  Could it be the time it takes from nVidia to the computer factories allow for oxidation to develop on chips not shipped in Nitrogen sealed packages to save a few dollars?


I have seen the same issue with Gateway, Dell, HP and others.


Also appears to have a dead short between layers of the motherboard.  Usually caused by forcing upside down harddrive into slot or screw or another part inside laptop.


DIAGNOSIS: Not Repairable



Dell XPS No Video

This Dell XPS comes in with 2 others, so after months of none, now three in one day. Various issues and  different problems.


Shift-Click to see larger image
The first one has a pink shell. Exact model number not copied yet. It has no video but starts like it will go into P.O.S.T. but never does.  The LCD don't not light, or flash briefly (which indicates the inverter works). Removing the keyboard and top I noticed this burnt plastic mark next to one of the connectors for the LCD.  


With motherboard removed, the plastic cover was slowly removed and noticed a coil with pads damaged so there was no electrical path completed. Removing the damaged coil and cleaning the area, required me to also remove a few mm of laquer from the mobo.  This exposes copper which will become the 'new' pad completing the circuit.


Test and backlight and video appears on LCD. So the problem was an open path by blown coil.  

Sunday, February 13, 2011

Tips on Testing MOSFETs

Imagine the flow direction
Source to Drain

This is how I test FETS 
What I will try to do here is to provide a little insight on how to test MOSFET's in circuit the easiest way I can think of. Essentially the FET acts as a switch, and the GATE either opens or closes the switch. When power is supplied to Pin 4 (usually the GATE) it will either open or close depending on the type of MOSFET it is. The arrows shows the direction for reference when using a meter to test.  

Setting the meter in DIODE mode.
On the N-Channel FET place the NEG lead on Pin 6/7 and the POS lead on Pin 2/3. You should get a reading of some value ~100 to 500 or higher.

Imagine the flow direction
Drain to Source
On the P-Channel FET place the POS lead on Pin 6/7 and the NEG lead on Pin 2/3. Again you should get a reading of some value ~100 to 500 or higher.
The reason I say pins 2/3 and 6/7 is because they are common, and it's less of a shorting risk than saying pin 3, which could slip and give you the wrong reading if pin 4 is touched or blow it if it has power on it (from battery or charger).

Most companies make it fairly easy to identify P-Channel from N-Channel parts by part number.  This is usually the case with U.S. companies.  National Semiconductor, Fairchild and others. But it is not a hard and fast rule with some Chinese manufacturers, and may need to check the datasheet before assuming they will be the same.

ODD number MOSFETs are considered to be P-Channel
EVEN numbered MOSFETS are usually N-Channel. 
Example: FDS6679 would be a P-Channel and FDS6690 would be a N-Channel MOSFET
FDS stands for Fairchild part
SI stands for Siliconix/Vishay part
AO stands for Alpha and Omega Semiconductors part
IOR  stands for International Rectifier part (Their numbering system may not adhere to above numbering system)

Saturday, February 12, 2011

DV5-1124 Motherboard replaces -1125

Insistent Customers and Laptop Repairs -Arrrrg!!!
What I had to do to get  a laptop back to the customer before factory heat-sink is replaced.


DV5-1124 motherboard without heat-sink
This customer was without their laptop for a couple of weeks [from another shop] waiting on the correct motherboard  to arrive. When the new motherboard arrived, it did not come with video memory management unit (mmu) heat-sink. After running a few minutes, the mmu would overheat and the unit would shutdown to protect the chip. An irate customer could not do without for another 3-5 days waiting on the factory heat-sink. So a minor custom heat sink was made to 'hold-off' the customer until it arrived.


It consists of a copper pad, plastic sheeting (on underside of pad) with a cut out hole. The copper bridge soldered to the pad was to act as a heat bridge to transfer heat to the original heat-sink.  This is not a recommended repair, only a temporary fix.  There were no guarantees presented with this method, and only allowed the customer time to use the important files until the correct part arrived.  There were no temperature measurements taken after the 'fix' only run-tests. 


DV5-1124 motherboard with
temporary heat-sink
Previously the unit would run about 2 minutes before shutting down due to heat. After the 'fix' the unit was stable enough to run without shutting down. So problem solved* until replacement arrived.


With the various model numbers of the DV5 series, it is wise to pay attention to the dash numbers of motherboard replacements. DV5-xxxx - 


In this case: the original board was DV5-1125 and replaced with DV5-1124.  The minor difference in the model number had larger implications. The original used shared video memory and the replacement uses on-board memory. Though more ram memory available is for Windows/applications/programs, an additional part (MMU heat-sink) was needed.  I hate to do mods but had to in this case.


Note: plastic sheeting with cut-out for MMU ceramic was done because the chip has resistors on top, if there was no insulation it would present an opportunity for the copper pad to short the resistors,If laptop grabbed from bottom or picked up in an unusual manner. This would either blow the MMU chip, or cause improper memory addressing, depending on what section is shorted.  MMU heat is transferred across bridge to larger mass of the main heat-sink. Engineering students may need to know thermal dynamics well to understand how heat travels.

Note: High Temperature hot glue was used on corners to hold copper pad to chip after thermal compound was applied to copper pad. The glue is easily removable when cooled, without pulling parts from motherboard.


Note: The 2cm rubber blocks were used to press the copper pad down when reassembled into case.

Shift-click (Shift-Tick) to see larger images without being redirected.


Do Not Copy this method since it is a temporary repair!~

Friday, February 4, 2011

DV6000 Powers On/Powers Off [Intel]

DV6500/DV600 SE series


Unit arrived with a common issue among INTEL Dual Core units.  Powers on then shuts off immediately.  Though there can be several causes of this symptom, usually the case is 'cheap'/bargain  ceramic capacitors. When shorted they can also short the AO4914 chip shown in the center of the Zoom-Out picture. In this case the cap marked with the red X is shorted. When removing it split in two horizontally. The two caps on the on the other side has also been known to short previously.  This can also lead to NO Charge, or never reaching 100% charge, or Working on AC but not on battery.  So on the Intel models I check all the ceramic caps in the Power In section first. (well at least after a visual of USB ports and other obvious problems- power plug/charger etc...)




Steps Taken:


Check Ceramic caps in power in section
Locate shorted parts (also checking AO4914 Dual Channel MOSFET)
Replace capacitor
Test
Reassemble
Test Again (also with battery in)
Start Windows (XP or Win7) check battery levels in Control Panel or BIOS
Allow battery to charge.

DV 2500/DV2000 SE Will not P.O.S.T./No Power

Click to Enlarge
HP DV 2500 14.1"
Intel Dual Core - Dead



DV2500 model number  and of the DV2000 Special Edition series that exhibits power problems. The indication of power problems were shown by the ring-light on the DC Jack. Since the LED uses the +5v line this points to a problem in the low power section of the unit. There were no other symptoms other than not powering on, or rapidly shutting down.


Sections also controlled by the +5v

  •  Power ON Button
  •  LED's and panels
  •  DC Jack Power indicator (ring light)



After close examination, found that the USB port was shorted.  This was a clear visual short. PIN 1 is +5v for the USB which is Vcc or 5v for powering device that is plugged into port.  With a dead short the power controller (usually a MAXIM IC) will not allow the rest of the unit to turn on. Though making troubleshooting a little more challenging, it protects the motherboard from additional damage as well as other parts.


Steps taken:
Remove damaged USB port
Clean solder holes
Replace USB port
Test
Reassemble
Test Again.

Sunday, January 30, 2011

For Advanced Techs

Click to Read QRCode
After answering questions from average users it appears that things may need to change to better serve techs.  Though previously stated, this is a help site for techs, I have been inundated with questions from users.  Stay tuned.

Sunday, January 16, 2011

Toshiba X305 - Powers On, Charge Light but Dead no Video

(Pic 1) bare motherboard on bench
This comes from a cousin via UPS from Indianapolis and promised him I'd take a look at it.  The Toshiba X305 is a nice looking machine but still has the flawed nVidia chip design. Disassembling the unit to be able to work on the motherboard without having to have all the connections was a challenge, but eventually I got the unit to work on the bench. Using the Power Jack and external video, it powered on with external video. 


This tells me two things. One the GPU is OK but the video memory is defective or not addressing all the lines of the GPU properly. 


Picture 2 with the stripes definitely tells me that it is the video memory! Now attempting to repair this issue is similar to the reflow heat process used on an earlier DV series video issue 
(with video).  


Picture 3 shows the second screen attempting to boot from network adapter but the characters are incorrect and pixelated. 


Picture 4 shows the video daughterboard. 
(Pic 2) Lines on external display


(Pic 3) Post screen attempting to boot to network
(no hardrive installed)
After attempting repair using the reflow process the video still has lines, varying from one pattern to another, but still lines are displayed. What's next?
  
The choices are:
Attempt to downgrade the video memory from 
512mb to 256mb by removing the memory from the
bottom side of the daughterboard.  If the defective ram is in the second bank of ram the problem would be solved.  If not the card will have to be replaced. And cost becomes an issue since most of the cards on eBay are overpriced. Even noticed a 
dead video card for this model selling for $149~!!!
(Pic 4) The culprit nVidia daughterboard


Replace the daughterboard to have a working laptop.  So this week I will have to do some selecting from the various items available.


Note: Video shown on external monitor, but not on laptop LCD.


Updates to follow.


Update 1
Preparing to reball the video card since the card itself is hard to find, and expensive.  A real time consuming test process because the laptop has to be partially assembled to test each repair/reball attempt.

Update 2
Reballing is not an option. Since the solder balls are smaller than equipment available.