Saturday, January 23, 2010

Dell Inspiron 1501 - Dead, No Power, Won't Charge

Picture 1
This is a common problem with the Dell Inspiron 1501/E1705/6000 series. Most of the motherboards use the same general layout and design. You can tell by the white and silver cases used. From my guess, the solder on the leads of FL1 [filter] tend to lose contact after regular use. Perhaps eating away at the Filters pad, due to the current it is carrying.

Sometimes it may be years before it finally lose contact, other times only months pass. In this instance the laptop was a couple of years old before it failed.

How to fix it:
Picture 2
Remove FL1
Clean contact area

Replace FL1
Solder back onto clean surfaces.

Click picture to see larger image

Picture 2
Shows another failed NO Charge issue. FL1 cannot handel the surge when plugged in and eventually arcs then lose contact with the solder pad.  In this case if you cannot find a replacement, you can simply turn the coil [FL1] upside-down, and make sure you have positive voltage on  the circuit.  Try to test pad contact area and not just the coil. If you check the coil only, sometimes you may not have contact to the pad, which is the original problem.   The silver dots on the motherboard in a circuit are test points. The white dots are only Pin 1 indicators or orientation markers. In picture 2 voltage was checked at pins 1,2,3 to see if voltage reached the MOSFET. This FET sends power to the RUN circuit.

If you wiggle the jack with the adapter plugged in and the lights come on briefly it is a  failed POS circuit.  [Top side]

If you get no lights or anything with adapter plugged in- it is usually a failed negative circuit.  [Typically bottom side]

HP NX6220 -Intermittent power problem

This HP NX6220 exhibited a number of symptoms but would never show the same one twice in succession. So it was a challenge finding the weak/bad part. As it turns out it was a capacitor under the Wi-Fi card. [Same value as cap to the right]

Replace part and continue checking and checking and turn on. Dead, nothing, no lights, no charge no anything. the choice becomes - Replace or Return to customer since the number of hours are starting to add up with no additional progress.

Gateway MA7/MA3/MA2 - Dead, Won't Charge

Gateway MA7 - MX6958*
Centrino Duo

Dead, Battery will not charge
Works with good battery,
Will not work with Adapter

This unit arrived with a common problem that DC jacks presents. However when you continue to use with the defect, it eats the copper around the POS terminal of the jack. In this case the copper had been eaten away, as well as shorting between planes of the motherboards phenolic. So there is only one way to resolve it, by bypassing that section (if possible). The condition of this MA7 was too far gone to be able to bypass.

One picture shows the scorching under the copper, the other shows the current path of the DC In.
Will verify the model number when returning to shop

Saturday, January 16, 2010

Acer Aspire 3680 (Dead)

Click Image For Larger View
Click Image For Larger View
Click Image For Larger View
ACER Aspire 3680-xxxx

This unit comes in Wednesday with symptoms: DEAD
Will Not Charge
Will Not Work With Good Battery

Diagnosis begins by following the DC IN from the DC Jack. The voltage would drop to 3v and not enough to power laptop or close any gates on the MOSFETs.

Taking the MOSFET [FDS6675] source side out of circuit shows the direction of the shorted components. Since the power branches to the
charge section or the run section with the other MOSFET shown below it. Checking to voltage at the source shows +19v. When in soldered on the board, the MOSFET DRAIN voltage is +3v. After replacing the FDS6675 the DRAIN side is still shorted.

Further testing indicates larger capacitor shown (in circle picture 1) is also shorted, removing it from circuit voltage on Drain side is now +19v. But the laptop would not turn on.

Still further testing and following the circuit path leads to the top side (facing technician when opened) to a series of three capacitors. Removing one side of this bank and testing each capacitor finds the shorted capacitor. As it turn out it was the topmost cap (marked with X in image), and when removed it was horizontally spit into 2 pieces.

Replace Capacitor.

Unit lights up!
Sorry for the picture orientation, but it appears blogger puts them in reverse sequence

You can read up on how MOSFET works in WIKIPEDIA
But in simpler terms -
There are 3 basic parts of a MOSFET. Source, Gate and Drain.

It acts as a doorway. When power is supplied to the GATE current or voltage crosses to the other side. In most laptops, common MOSFETs are 8 pins.
Pins 1,2,3 are SOURCE (power or current in)
Pin 4 is the gate
Pins 5,6,7,8 is the DRAIN (power or current out)

There are more complex MOSFETs such as Dual Channel with 2 gates, 2 sources, or 2 drain it is large matrix of numbers and combinations. P-Channel, N-Channel and others. Knowing what is what requires a good memory, manual or cross reference index.

Dell Latitude D600

A relative common problem with Dell D600 is the right hinge failing, and the laptop screen will not stay in place. The inner bushing of the lid hinge becomes worn, or siezes and when the user forces the lid up to view the screen the bushing breaks. This is a simply a replace hinge repair.

Remove LCD Bezel
Remove screws holding right side of LCD
Remove screws on edge of LCD (4)
Remove 1 screw from top of LCD
Replace hinge

Sunday, January 10, 2010

What Kills HP DV series laptops?

The number one issue with DV Series is:
Blank or No Video displayed.

The number two issue is: (tied)
No Wi-fi or Continuous rebooting

After repairing a number of HP DV Series laptops. I wanted to isolate the problem and make it easier for me to fix, and have them stay fixed! So digging deep into them I can only come to a couple of conclusions of why they fail.

1: Manufacturing - Hann-Starr
Either the oxidation on motherboard or the Graphics Chips. Since the failure comes in both versions AMD and Intel lines. And in Intel and nVidia GPU's it seems it could be at the factory.

2: Distribution - nVidia
Could the transit time and shipping packaging be contributing to the oxidation on the GPU? On one unit after a number of reflow failures, I decided to remove the GPU and prepare to 'reball' the chip. Then and only then did I notice there was no solder on some pads. So that points the finger to nVidia. Oxidation is the culprit since the solder balls are put on a the the GPU plant.

3: Bad Solder
I have heard claims from HP techs that nVidia got a bad batch of solder. But I don't believe that because the problem exists on DV2000, DV6000, DV9000, V6000, F700, C500 lines. Too many fabrication points for the same solder issue. As well as the number of years that this problem has been known.

Can they be fixed reliably? Yes
But it would require a good knowledge of solder's metallurgic properties, heat and manufacturing processes. The training I received from my previous employers helped quite a bit. And now repair them from various shops in the area as well as California, Ohio, Illinois and whoever can find my address or contact me.

Will I post how to permanently fix them? Not just yet.
This information will be posted in a technical manual. And people that want to learn how to fix them will have the option of getting a complete kit. Because I don't want them to fail, then blame me for not following directions.

How much did the tools cost altogether?
The cost of all the tools and equipment to fix the DV series was about $100 max. And the would include custom items made.

Blanket tricks and gimmicks
They work (sometime) but the result is not permanent and usually used as a 'get it out' solution. These units sometime wind up on eBay, Craigslist and other venues as 'working' units. But fail in a couple of days or weeks. This does nothing for the corrosion/oxidation which is the ultimate issue.
Tricks seen posted: Wrap in blanket, placing a tea candle on GPU, put in oven and other silly methods that unskilled/untrained hobbyists use

What can happen when it is done wrong?
The board can be rendered useless, shorted and a total mess. requiring replacement or reballing which is a time consuming, expensive and painstaking process.

When overheated:
All the solder under the GPU will tend to collect forming a large blob under the chip. Shorting GPU.
Adjacent caps, resistors, coils will be dislodged.
Fan connector will be burnt.

When underheated:
Wastes time, and will not be repaired or work
Presents or create another problem that will be difficult to determine.

Number of units repaired since Jan 1, 2010

Total units repaired

(update 3/23/2010) Now averaging 7-10 a week

IBM Thinkpad R40 DC Jack

No matter how many times I stress that when the jacks start to fail, you should take it to the shop. With each delay and use the problem only gets worse and more expensive. Wiggling the DC Jack to make the positive side supply power to the board eats copper! Every time there is less surface pad left, and eventually you will totally eat all the surrounding copper making a 25 min job into a 1 hr job (or worse - unrepairable).

This jack nearly killed the motherboard which would require a replacement (expensive).

Saturday, January 9, 2010

Toshiba TECRA L2

Toshiba Tecra L2
Symptoms: DEAD, No Lights, No Charge Light, No response to power button.

This model has had it's issues with the DC Jack. And because the jack breaks at the elbow bend directly behind the IN lead, many techs will miss this and assume further or more complex problem. Then replace the motherboard.

It's simple, follow the power from the IN source. After checking the power supply and there is no power on the motherboard follow the IN lead for voltage. Start at the DC Jack and work you way forward. IF no power is on the rear of the DC jack, suspect the jack first. Visual inspection is the key. Because this model uses plastic clips to keep the lead straight it will often be missed.

*This jack is also used on GATEWAY MA2, MA3, MA6, and MA7 series laptops

DV9000 Freeze and Shut Off Issue

DV9000 arrived seemingly working well until touched. Upon inspection I noticed that when I would use the right palmrest the unit would shut off unexpectedly. Rebooting, I tapped the area mentioned above. Again it shut off. Reboot this time not touching the unit other than the power button. The Vista OS would load, but hang before completing start up.

Disassemble the laptop and visually inspect for short or open connections. During the removal of the hard drive I noticed that SATA1 connector was damaged. This would definitely cause the
freeze during boot. Upon further inspection I notice that USB1 was damaged. Pushed in and the pin 2 & 3 were touching the outer portion of the connector that is negative ground. This would cause the shut down.

Completely remove the motherboard and replace the USB and SATA1 connector. Not as easy as it seems because the small area to heat and desolder pins. I typically use a magnifying headband and plenty of light. With insufficient lighting many mistakes can happen, or be missed and/or cause further permanent damage.

*The DV9000 comes with 2 SATA connectors as opposed to the DV6000 or Compaq V6000, F700 which only has one connector.

After replacing the USB and SATA connectors, fired up the unit and all appeared to be working normally. The unit runs for 2 hours, turn on WIFI to connect to net and LCD goes milk white. No Video Data to LCD. This will require opening the bezel & lid to see if LCD is connected, or motherboard connector has failed. Should not be an issue but need to be resolved.

DV9000 Power Issue

This HP DV9000 arrived with power problems. Difficult to diagnose simply by looking at the bottom side of the board (which faces tech when opened). When the power cable was disconnected from the board an obvious scorched connector was noticed. This 4 pin plug supplies power to 2 sections.

Not wanting to be too verbose, I will simply say that all 4 connections to the motherboard are needed and when one pin is scorched and oxidized, it cannot provide adequate current or voltage. So the plug end was replaced, and the interior of the jack was cleaned of carbon residue from the scorching.

The number of issues with this unit, makes for a days work. Power issues, broken LCD issues, SATA connector, USB port all on one machine. Everytime I fix one issue another pops up. And the customer wants it fast, but at a cheap price. When does it end?

Friday, January 1, 2010

New Year Same Problems

Thinkpad T40 with NO CHARGE issue.

This also applies to: Run off Batteries, but will not work with AC adapter.

The power in section circuits are not completed and generally the MOSFETs are open, or the Fuse is open. Easy fix and not much diagnosis is needed.