Archive for February, 2011



 Notebook repair can be dangerous. The circuitry in your laptop is small and delicate. To the untrained eye, it can be hard to distinguish between one component and the next.

Small square shaped items of roughly the same perimeter are fixed into your laptop in so many places, how are you expected to know what chip performs what job?

If you are afraid of trying to solve the mystery of your broken laptop but do not want to send it in to a shop—or cannot afford the price tag, there is no reason to worry.

You do not have to turn it over to the professionals. While it may be tricky business unscrewing the cover and looking beneath the skin of your laptop to perform notebook repair, learning how to address any number of problems is only a matter of receiving the education you need.

And the surprising truth is: you do not need to shell out hundreds of dollars to get a tech degree in order to fix yours and other people’s laptops. You only need to be directed to the right resources to learn the trade for yourself.

The laptop repair videos at http://www.laptoprepairvideos.com can teach you the necessary skills to work on your own laptop. They have an astounding ten hours of laptop repair videos that address issues from motherboards, to broken keyboards.

They show you step by step repair processes for battery repair, CD/DVD repair and of course, the right way to take your laptop apart. But what is more comforting is that the videos are in depth and cover even the most challenging problems you will face when engaged in notebook repair.

Even the most difficult tasks like soldering and repair work on your motherboard are addressed in the videos. The “how to” videos for these tasks are straightforward. The instructor does not use highbrow language that confuses you as you follow along and he moves at a speed that is easy to keep up with.

You will need a soldering iron and a few tools to follow along, but compared to turning your laptop over to a stranger who will try to wrangle as much money out of you as he can, the tools and the cost of the tutorial videos does not even scratch the surface.

Learning to repair your notebook can save you money and, if you become proficient enough, even make you money. For the whole ten hour program, you will only spend fifty-five dollars.

That is five and a half dollars an hour. Compare that to a college class and you are looking at a minimum of two hundred dollars saved an hour. You can come back to the videos over and over again until the process is so second nature to you that you can do it without assistance.

When that day comes, you will have acquired a skill that very few people have. From there, you could utilize the skills to help others fix their laptops and even make a career out of it.


With so many DELL laptops with the message “DELL AC Power adapter could not be determined” on the screen, it’s time to look into this with a bit more detail.

As already noted in breakdowns section, the DELL AC power adapter used for the DELL Latitude D610 has an Identification wire, which is the tiny center pin in the power plug.

Trying to figure it’s function from the outside proves to be futile. When detached from the laptop it carries no signal, voltage, capacity or resistance. It seems like a dead wire leading no where.

So it’s time to figure out where this AC Adapter Identification wire is going. After cracking the case of the DELL AC power adapter, brings about a mystery electronic component. It’s a transistor shaped component with 3 pins. The middle pin is connected to the AC Adapter Identification wire, the other pin to V- of the power plug. The 3rd wire is not connected. Pretty strange for a transistor, where all 3 pins are usually all connected.

DELL AC Power Adapter Identification Device
DALLAS 2501 component – connected to the 3rd wire in the AC power adapter cord

The casing of the transistor shaped mystery component has markings; “DALLAS – 2501 – 0613D2 – +571AA”. Not the typical markings on a transistor. Weird!!

At least there is DALLAS as the manufacturer ID. This is synonym for MAXIM semiconductor.

After a few searches in the MAXIM component database, the transistor shaped device is a UniqueWare™ Add-Only Memory, known under type DS2501, DS2502, DS2505 or DS2506. The difference is the size of the memory. The DS2501 seems to be 512 byte memory.  The memory is accessed using a 1 wire communication protocol known as “1-wire”.

So the DS2501 in the DELL AC Power Adapter contains the identification info of the power adapter. The DELL laptop reads the identification info during startup of when it’s connected while started. Power for the memory device comes from the laptop which is the same AC Adapter Identification wire, indicated as a “parasite power circuit”.

Pretty nifty solution – however, it proved to be a vulnerable one, with many victims. When communication with the UniqueWare™ Add-Only Memory fails, the laptop shuts battery charging down.

Causes why communication can fail and battery charging stops:

Broken  Identification wire in AC adapter lead

DC adapter plug center pin problem (bend or broken)

Motherboard DC jack contact problem

DC jack soldering loose on the motherboard

Dead UniqueWare™ Add-Only Memory (DS2501 etc)

Dead master / host controller chip on the motherboard

There is no “off the shelf” replacement for a DS2501 UniqueWare™ Add-Only Memory. The read-only (EPROM) memories are programmed in the factory with the AC power adapter identifier. Afterwards memory *can* be permanently locked, with only the possibility to add information in unused memory space.

A quick test to see if wiring, jack or plug is causing intermittent connections is to boot the laptop into setup mode. (Press F2 during startup) Go to the information item “Device Info” and watch the “Adapter type” field. Plug the AC Power adapter, the field is updated INSTANTLY if the laptop can communicate with the AC Power Adapter. If not the field doesn’t change for a few seconds and then reports “unknown AC adapter”.

  DELL Latitide D610 BIOS Boot Setup Screen - AC Adapter type
BIOS setup – testing the AC power adapter   
 
 

 

Move the cable, plug, jack if possible and see if the field is updated or intermittent. In this case it’s likely a loose contact.

If the field just says “Unknown Device Installed” all the time, try the adapter with a different DELL laptop – if it works in that case, it’s most likely the host controller chip on the mother boards or the power adapter adapter jack that needs re-soldering. In case the adapter doesn’t work for either laptop, it’s more likely the DS2501 UniqueWare™ Add-Only Memory is dead.

A new DS2501 can be soldered and programmed, with a “1-wire” programming kit and a PC with an ole RS232 jack. This is described in the Dallas Semiconductor application note 177. For electronics enthusiasts that’s just a bit of fun with a soldering iron and a few low cost components.

When the programming kit is ready, next is to read the identification data from a working DELL AC Power adapter and clone it into a new DS2501 chip, already soldered into the DELL AC Power adapter.

 
DELL AC Adapter not recognisedDELL ID chip diedDELL design failureInside a DELL battery

 

For most this kind of tampering is out of reach, and from the cost and time point of view, it would be quicker to just buy a replacement adapter in case the problem is the DS2501 UniqueWare™ Add-Only Memory.

In any case, with the technology for AC Adapter identification revealed, it boggles the mind why so many DELL laptops report the same message. It can’t be all wiring problems or a bad power plug / jack. Most laptop owners do not bash their equipment around like mad – like overland travel with a 4×4 truck is.

More likely, it could be a failure pattern that relates to the UniqueWare™ Add-Only Memory, the DS250X range from DALLAS / MAXIM Semiconductor. It could be so the memory looses it’s contents over time or static discharges ruins the circuitry of the memory chip.

After all the center pin of the AC power plug of the PA-1900-02D2 with revision number REV A04 is directly connected to the DATA pin of the DS2501. The center pin is like an antenna, it can pick up static electricity easily directly fed into the circuitry of the memory chip. From an electronics engineering perspective this is weird. Knowing it’s for mobile use and most likely should operate in rogue electrical conditions. The DS2501 in the DELL AC Adapter has no protective circuitry designed around it…..For a power-supply, I’d call this a design flaw…… 


Sony Vaio VGN-CR Series

Sony Vaio VGN-CR Series

Sony VGN-CR series laptops develop a common problem of abnormal shutdown.It seems to be heating problem but after cleaning or changing the heatsink,CPU and fan problem remains the same.

Affected models are:

VGN-CR11GH

VGN-CR12GH

VGN-CR14GN

VGN-CR22G

VGN-CR23G

VGN-CR24G

VGN-CR26GN

VGN-CR32G

VGN-CR34GN

VGN-CR35G

VGN-CR36G

VGN-CR37GN

VGN-CR313H

VGN-CR323

VGN-CR343N

VGN-CR353

VGN-CR363

This problem is related to motherboard and needs a chip level repairing.Some times laptop can work for full day but it shuts off without warning and time is not fixed when machine will shut off.

We have 100% solution for this problem and repaired atleast 50 Sony VGN-CR series laptops.