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SCENE OF THE CRIME *COMPUTERS* SUSPECTS RAM
MEMORY - If the POST displays less total memory than you have fitted, one of the
RAM modules has failed or worked loose. Remove and reseat all the chips. If this
works but the problem returns after a few weeks or months, check that you do not
have gold-edged SIMMs or DIMMs plugging into tin-coated sockets or viceversa. A
chemical reaction at the interface of these two metals slowly worsens electric
contact. If re-seating doesn’t help, remove each module in turn until you
locate the faulty unit, remembering not ot leave any SIMM banks half-empty.
aPost error messages in the 2xx range or parity check errors also indicate
faulty ram modules. POWER
SUPPLY – Press the On button. If the LED doesn’t come on, check the AC power
supply. Is the PC plugged in? Check the fuse. Now plug the PC’s power lead
into the monitor. If the monitor switches on OK, the problem lies with the DC
supply from the PSU in the PC. A flickering power LED, PSU fan spinning up and
down erratically, error messages beginning 01 or 02 on the POST or the PC
turning itself off abruptly after a successful startup are all also symptons of
a faulty DC supply. If removing expansion cards and/or disk drives helps, the
PSU needs to be replaced with a high-wattage unit. MOTHERBOARD
– If ram modules are not recognised in one particular socket or expansion
cards consistently appear dead in one of the expansion slots but work in all the
others, check that none of the metal fingers in the socket are bent or missing.
If the system time runs slow or you see POST error messages 102, 103, 161-164,
199 or anything beginning with 17, try replacing the CMOS battery. A hard disk
that is repeatedly not recognised until you run the autodetect sequence from the
BIOS setup program is also a symptom of a flat CMOS battery. If the system does
not reach the POST but all the power LEDs are on and fans spinning, the
motherboard is dead. CPU
– CPU failure is very rare – the motherboard normally blows first and
protects the processor, like a very expensive fuse. Overclocked processors can
cause system malfuncions, though; erratic lock-ups and reboots are the sysmpton
of this. Upgrading to a much faster processor can also put a strain on slower
components, particularly the RAM by forcing it to run faster. If the PC reboots
after prolonged periods of use and then fails the POST or does not start
windows, this indicates an overheating problem. If reboots occur when running
the same programs, regardless of how long the PC has been on, the CPU may be
drawing more power than the PSU can supply. This is a problem with the Athlon
systems. VIDEO
– Power LED on, fan spinning but nothing shows on the screen. If you hear one
long and two short beeps, this is a graphics card fault. If you don’t, blame
the monitor. Try removing the graphics card and re-inserting it. If you have a
graphics chip integrated on your motherboard and you are overriding it with an
expansion card, remove it. If the built-in graphics don’t work, the
motherboard has probably blown. If it’s just the expansion card that fails,
the check that the BIOS is overriding the built-in graphics correctly. A flat
CMOS battery can cause this setting to be lost. Monitor faults are usually
caused by a blown transformer. This is not user-serviceable. HARD
DISK – Error 1702 or ‘drive not ready’ messages indicate a failed hard
disk or drive controller. Test which by plugging the drive into the secondary
IDE connector and booting from a floppy disk. Make sure that the ribbon cable is
not damaged and that the red wire is aligned with pin 1 on the connector.
‘General failure reading drive C’ is normally caused by data corruption.
Boot and run scandisk from a windows recovery disk. Then back up your data and
replace the drive. Low groaning noises coming from the drive, accompanied by
erratic spinning up and down of the disk indicate a problem with the drive
motor. Try a different power cable. If that doesn’t help, replace the drive. TOOLS
OF THE TRADE BASIC
ADVANCED
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