Tuesday, 29 September 2015

Troubleshooting Problems With Facebook

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The origin of Facebook, Initially known as thefacebook, Mark Zuckerberg founded Facebook while studying at Stanford University along with collage mates Eduardo Saverin, Dustin Moskovitz, and Chris Hughes on Feb 4, 2004.

The controversy around Facebook started quickly.  A week after he released the website in 2004, Zuckerberg was charged by three Stanford senior students, Cameron Winklevoss, Tyler Winklevoss, and Divya Narendra of having thieved the idea from them. Zuckerberg faced charges of violation of security, breaking copyrights, and breaking individual comfort for taking the university student images he used to promote the website. He also experienced expulsion from Harvard University for his activities. However, all charges were gradually dropped.

Facebook is the largest online social networking service on the web, Primarily focused on high school to college students. Within months, Facebook and its primary idea distribute across the dorms of Harvard  University where it was very well received. Soon enough, it was prolonged to Yale and Stanford Universities.

The network was quickly extended to other Boston universities and eventually all US colleges. It became Facebook.com in 2006 after the address was purchased for $200,000.
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Monday, 28 September 2015

Exchanging the System Board

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If possible, back up the contents of the systems hard drive to some other media before removing the system board. Also, record the CMOS configuration settings, along with the settings of all jumpers and switches, before exchanging the system board.

Remove the video and disk drive controller cards from the system boards expansion slots. Disconnect the system board from the power supply unit and the system board front panel connections. Take care to make any connection removed from the system board, and its connection point, to ensure proper reconnection. Exchange the system board with a known good one. Reconnect all the power supply and front panel connections to the system board. Reinstall the video and disk drive controller cards in the expansion slots and try to reboot the system.


Reconfigure the system board to operate with the installed peripherals. Reset the video and disk drive controller cards in the system unit. Reset the CMOS setup to match the installed peripherals and turn on the system.

When the system boots up, reinstall any options removed from the system and replace the system units outer cover. Return the system to full service and service the defective system board. If the system still does not boot-up. retest all the system components one at a time until you find a cause. Check the small things such as cable connections and key switches carefully.

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Motherboard Hardware Checks

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If the systems CMOS configuration setup appears to be correct and a system board hardware problem is suspected, you probably need to exchange the system board for working unit. However, a few items are worth checking before doing so.

Check the system board for signs of physical problems, such as loose cables and devices. If noting is apparently wrong, check the power supply voltage levels on the system board. Check for +5V and +12V (DC) on the system board. If these voltages are missing, turn off the system, disconnect power to all disk drives, and swap the power supply unit with a known good one.

On-board FRU Devices

Finally check the FRU devices present on the board. Normally, a few serviceable items on the system board might be checked by substitution before doing so. These include the RAM modules, the microprocessor (and its cooling fan), the ROM BIOS chips. and the system battery.



* RAM: These system boards memory is a very serviceable part of the system. RAM failures basically fall into two major categories and create two different types of failures. The first category of memory errors, glitches int he operation of applications and the system. You can clear these events just by restarting the system. However, the other category of RAM failures are referred to as hard memory errors. These are permanent physical failures that generate NMI errors int he system and require that the memory units be checked by substitution.

You can swap the RAM modules out in a one at a time manner, to isolate defective modules. These modules ae also swapped out when a system upgrade is being performed. The burn-in tests in most diagnostic packages can prove helpful in locating borderline RAM modules.

Take care when swapping RAM into a system for troubleshooting purpose to make sure that the new RAM is the correct type of RAM for the system and that it meets the systems bus speed rating. Also, make sure that the replacement RAM is consistent with the installed RAM. Mixing RAM types and speeds can cause the system to lock up and produce hard memory errors.

* MICROPROCESSOR: int he case of the microprocessor failure, the system may issue a slow, single beep, with no display or other I/O operation. This indicates that an internal error has disabled a portion of the processor's internal circuitry (usually the internal cache). Internal problems also may allow the microprocessor to begin processing, but then fall as it attempts operations, Such a problem results in the system continuously counting RAM during the boot up process. It also may lockup while counting RAM during the boot up process. It also may lockup while counting RAM. In either case, the only way to remedy the problem is to replace the microprocessor.

You can easily exchange the microprocessor on most system boards. Only the 80386SX is a soldered in device. However, the fact the most microprocessors, as well as the BIOS chips, are mounted in sockets brings up another point. These items should be pulled and reseated in their sockets. If they seem to be a possible cause of problems. Sockets are convenient for repair and upgrade purposes. But they also can attract corrosion between the pins of the device, and those of the socket. Over time, the corrosion may become so bad that the electrical connection becomes too poor for the device to operate properly.

* ROM: Like the microprocessor, a bad or damaged ROM BIOS typically stops the system dead. When you encounter a dead system board, examine the BIOS chips for physical damage. If these devices overheat, it is typical for them to crack or blow a large piece out of the top of the IC package. Another symptom of a damaged BIOS is indicated by the boot up moving into the CMOS configuration, but never returning to the boot up sequence. In any case, you must replace the defective BIOS with a version that matches the chip-set used by the system.

* Battery: Corrosion also can affect the system clock over time. If a system refuses to maintain time and date information after the backup battery has been replaced, check the contacts of the holder for corrosion. Two types of batteries are commonly used for CMOS backup: Nickel Cadmium (Ni-Cad) and lithium batteries. Of the two, Ni-Cads have historically been the most favored. Conversely, Lithium batteries are gaining respect due to their long life capabilities when installed in system designed to recharge lithium batteries. However, Lithium battery life is noticeably short when they are installed in systems designed for the higher current drain Ni-Cads. Therefore, you should always use the correct type of battery to replace a system board battery.

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Motherboard Software Checks

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Boot up the system and start the selected diagnostic program if possible. Try to use a diagnostic program that deals with the system board components. It should include memory, microprocessor, interrupt, and DMA tests.

Run the programs system board tests function and perform the equivalent of the all test function. These types of tests are particularly good for detecting memory errors, as well as interrupt and DMA conflicts. Note all the errors indicated by the tests. If a single type of error is indicated, you might be able to take some corrective actions, such as replacing a memory module or re-configuring interrupt/DMA settings, without replacing the system board. If more complex system board problems are indicated, however, exit the diagnostic program and use the following hardware checks and installation/removal procedure to troubleshoot and replace the system board.


You can use the DOS MEM command (MEM.EXE) to view the system's memory utilization scheme. It displays bothe the programs currently loaded into memory, and the systems free memory areas. You can use the /C switch with the MEM command as a valuable tool to sort out TSR conflicts in upper memory. Likewise, you can add a /D switch to the MEM command to view detailed information about memory usage. This switch gives very detailed information about all items stored in memory.

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Motherboard Configuration Checks

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Observe the boot-up RAM count to see that it is correct for the amount of physical RAM actually installed in the system. If not, swap RAM devices around to see whether the count changes. Use logical rotation of the RAM devices to locate the defective part.

Normally, the only time a configuration problem occurs is when the system is being set up for the first time, or when a new option is installed. The other condition that causes a configuration problem involves the system boards CMOS backup battery. If the battery fails, or has been changed, the contents of the CMOS setup will be lost. After replacing the battery, it is always necessary to run the CMOS setup utility to reconfigure they system.

The values stored in CMOS must accurately reflect the configuration of the system; otherwise, an error occurs. You can access these values for change by pressing a predetermined key combination during the boot-up procedure.

In Pentium-based systems, check the advanced CMOS configuration and enabling setting in the BIOS and chipset features screens. These settings, illustrated in figure 2.4, usually include the disk drive, keyboard, and video options, as well as on-board serial and parallel ports.

In addition, the user can turn on or off certain sections of the systems RAM for shadowing purpose and establish parity or non-parity memory operations.

Incorrectly set BIOS enabling parameters cause the corresponding hardware to fail. Therefore, check the enabling functions of the advanced CMOS settings as a part of every hardware configuration troubleshooting procedure.

In some BIOS, holding down the Del key throughout the startup erases the CMOS contents and starts from scratch. Jumpers that can be set to start the contents from a bare-essentials setting may also be placed on the system board. In either case, you must rebuild any advanced features in the CMOS configuration afterward.

Newer system boards have an auto-configuration mode that takes over most of the setup decisions. This option works well in the majority of applications. Its settings produce an efficient, basic level of operation for standard devices in the system. However, they do not optimize the performance of the system. To do that, you must turn off the auto-configuration feature and insert desired parameters into the configuration table. There are typically two options for the auto-configuration function.

* Auto-configure with Power-On Defaults
* Auto-configure with BIOS Defaults

Using power-on defaults for auto-configuration loads the most conservative options possible into the system from the BIOS. This is the most effective way.

Typically, if the boot-up process reaches the point where the system CMOS configuration information displays onscreen, you can safely assume that no hardware configuration conflicts exist in the systems basic components. After this point in the boot-up process, the system begins loading drivers for optional devices and additional memory. If the error occurs after the CMOS screen displays and before the boot-up tone, you must clean boot the system and single step through the remainder of the boot-up sequence.

The many configuration options available in a a modern BIOS requires the user to have a good deal of knowledge about the particular function being configured. Therefore, an extended discussion of the advanced CMOS setup options cannot be conducted at this point . However, such information is covered along with the system component it relates to as the course moves through various system components.

CMOS setup utilities may also offer a wide array of exit options. One common mistake in working with CMOS configuration settings is that of not saving the new settings before exiting. When this happens, the new settings are not stored, and so that old settings are still in place when the system reboots.

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Sunday, 27 September 2015

SYSTEM BOARD SYMPTOMS

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So much of the systems operation is based on the system board that it can have several different types of symptoms. Typically symptoms associated with system board hardware failures include the following:

* The On/Off indicator lights are visible, the display is visible on the monitor screen, but there is no disk drive action and the machine does not boot up.
* The On/Off indicator lights are visible, the hard drive spins up, but the system appears dead and there is no boot up.
* The system locks up during normal operation.
* The system produces a beep code with 1,2,3,5,7 or 9 beeps.
* The system produces a beep code of 1 long and 3 short beeps.
* The system will not hold date and time.
* An 8042 Gate A20 Error message displays error getting into protected mode.
* An Invalid Switch Memory Failure Message displays.
* A DMA ERROR message displays DMA controller failed page register test.
* A CMOS Battery Low message display, indicating failure of CMOS battery or CMOS checksum test.
* A CMOS System Option Not Set message displays, indicating failure of CMOS battery or CMOS checksum test.
* A CMOS Checksum Failure message dsiplays, indicating CMOS battery low or CMOS checksum test failure.
* A 201 error code displays, indicating a RAM failure.
* A parity check error message displays, indicating a RAM error.


Typical symptoms associated with system board setup failures include the following:

* A CMOS inoperational message displays, indicating failure of CMOS shutdown register.
* A Display Switch Setting Not Proper message displays failure to verify display type.
* A CMOS Display Mismatch message displays failure of display type verification.
* A CMOS Memory Size Mismatch message displays system configuration and setup failure.
* A CMOS Time & Date Not Set message displays System configuration and setup failure.
* An IBM compatible error code displays, indicating that a configuration problem has occurred.

Typical symptoms associated with system board I/O failure include the following:

* Speaker doesn't work during operation. The rest of the system works, but no sounds are produced through the speaker.
* Keyboard does not function after being replaced with a known good unit.

Most of the hardware problems that occur with computers, outside of those already described, involve the system board. Because the system board is the center of virtually all the computers operations, it is only natural that you must check it at some paint in most troubleshooting efforts. The system board normally marks the end of any of the various troubleshooting schemes given for different system components. It occupies this position for two reasons. Firs the system board supports most of the other system components, either directly or indirectly. Second, it is the system component that requires the most effort to replace and test.

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System Board Problems

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Problems related to the system board can be difficult to solve because of the system boards relative complexity. So many system functions rely at least partially on the system board that certain symptoms can be masked by other symptoms.














Begin by observing the symptoms produced by boot up and operation. Observe the steps that lead to the failure and determine under what conditions the system failed. Were anay unusual operations in progress? Note any error messages or beep codes. Retry the system several times to observe the symptoms clearly. Take time to document the problem write it down.

Refer to the user manuals for the system board and peripheral units to check for configuration problems. Examine the CMOS setup entries for configuration problems. In pentium system, also check the advanced CMOS setup parameters to make certain that all the appropriate system board enabliling settings have been made.

If possible, run a software diagnostics package to narrow the possible causes. There are many free diagnostic packages, PC Check is on such utility. Remember that the microprocessor, RAM modules, ROM BIOS, CMOS battery, and possibly cache ICs are replaceable units on the system board. If enough of the system is running to perform tests on these units, you can replace them. If sysmptoms suggest that one or more of these devices may be defective, you can exchange them with a known good unit of the same type.

If teh diagnostics program indicates a number of possible bad components, replace them one at a time until you isolate the bad unit. Then insert any possible good units back into the system and check them. You also should consider the possibility of bad software when multiple filed replaceable unit(FRU) problems are indicated

SYSTEM BOARD SYMPTOMS
CONFIGURATION CHECKS
SOFTWARE CHECKS
HARDWARE CHECKS
EXCHANGING THE SYSTEM BOARD
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Power Supply Problems

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If the front panel lights are on and the power supply fan is running, but no other system action is occurring, you should consider the power supply as one of the most likely sources of such a problem.


The presence of the lights and the fan operation indicate that power is reaching the system and that at least some portion of the power supply is functional. This type of symptom results from the following two likely possibilities:

1. A portion of the power supply has failed, or is being overloaded. One or more of the basic voltages supplied by the power supply is missing while the other are still present.

2. A key component on the system board has failed, preventing it from processing, even though the system has power. A defective capacitor across the power input of the system board can completely prevent it from operating.

Check the power supply by substitution. If the power supply is not the cause of the dead system, one of the other components must be overloading the portion of the power supply. You must sort out which component is causing the problem.
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Checking a Dead System

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Special consideration must be taken when a system is inoperable. In a totally inoperable system, there are no symptoms to give clues where to begin the isolated process. In addition, it is impossible to use troubleshooting software or other system aids to help isolated the problem.

The following discussion covers a standard method of troubleshooting dead microprocessor based equipment. The first step in troubleshooting any dead system is to visually inspect the system. Check for unseated cards, loose cables, or foreign objects within the system unit.


When the system exhibits no signs of life including the absence of lights the best place to start looking for the problem is at the power supply. The operation of this unit affects virtually every part of the system. Also , the absence of any lights working usually indicates that no power is being supplied to the system by the power supply.

1. Begin by checking the external connections of the power supply. This is the first step in checking any electrical equipment that shows no signs of life.
2. Confirm that the power supply cord is plugged into a functioning outlet.
3. Check the position of the ON/Off switch.
4. Examine the power cord for good connection at the rear of the unit.
5. Check the setting of the 110/220 switch setting on the outside of the power supply. The normal setting for equipment used in India is 22O.
6. Check the power at the commercial receptacle using a voltmeter, or by plugging in a lamp (or other 220v device) into the outlet.

If power is reaching the power supply and nothing is happening, the next step in isolating the cause of the problem is to determine which component is causing the problem. The most likely; cause of the problems is a totally dead system is the power supply itself. However, in a ATX system, if the cable that connects the system board to the power switch has become loose, the power supply will appear dead. Use a voltmeter to check for the proper voltages at one of the systems option power connectors. If any voltage is missing. check the power supply by substitution.

If the main power supply is not the reason the system is dead, one of the other components must be overloading the systems power supply. Under such conditions, it is normal for the system to trip the breaker, or to blow the fuse, in the commercial power system. You must sort out which components is affecting the power supply. Remove the peripheral devices so that only the basic system needs to be checked.

Divide the system into basic and optional sections for testing. Remove all external options from the system and restart the system. If the system begins to work, troubleshoot the optional portions of the system.

Finally, divide the basic system into optional and basic components. Remove all optional adapter cards from their expansion slots and restart the system. If the system begins to work, troubleshoot the various optional adapters by reinstalling them one at a time until the system fails again.

Note:
Before changing any board or connection, always turn the system off first. In an ATX style system, you should also disconnect the power cable from the power supply. This is necessary because even with the power switch off, there are still some levels of voltages applied to the system board in these units.
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Friday, 25 September 2015

Desktop Power Supply Problems

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Typical Symptoms associated with power-supply failures include the following:

* No indicator lights visible, with no disk drive action, and no display onscreen. Nothing works; the system is dead.
* The On/Off indicator lights are visible, but there is no disk drive action and no display on the monitor screen. The system fan may or may not run.
* The system produces a continuous beep tone.


The power-supply unit is one of the few components in the system that is connected to virtually every other component in the system. Therefore, it can affect all the other components if it fails.

While tracking down power-supply problems it must be kept in mind that in addition to the obvious power connections. The power supply also delivers power to other components through the system board. These include:

1. All the options adapter cards(through the expansion-slot connectors)
2. The keyboard (through the keyboard connector)

Power-supply problems can cause symptoms to occur in all of these areas, and problems in any of these areas can affect the operation of the power supply.

CHECKING A DEAD SYSTEM

OTHER POWER-SUPPLY PROBLEMS
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