Hardware Reference
In-Depth Information
Photo 13.4
Connectors can often be problematic and are a frequent cause of
intermittent hardware faults. In this case, the rightmost serial ATA (SATA)
connector is not correctly seated. Simply pushing the connector fully home
was sufficient to clear the fault!
procedures are completed an appropriate message is printed on the screen. Fur-
thermore, once the initial procedures have been completed, any disk drive fitted
to the system will normally become active as the system is 'booted'. If neither
of these indications is produced, the system motherboard must be suspected as
the fault will probably be attributable to failure of the CPU or one of the major
VLSI support devices present.
At this stage it may be worth replacing the system motherboard with a known
functional unit. If this is not possible, checks should be performed on each of
the VLSI devices starting with the CPU. Where a fault is intermittent (e.g. the
system runs for a time before stopping) it is worth checking connectors and also
investigating the cleanliness of the supply. It is also worth checking for devices
that may have become overheated after a period of operation. Check also, that
CPU voltages have been correctly set. Attempts to overclock a CPU will often
result in overheating - particularly if the CPU core voltage has been raised.
Connectors are often prone to failure and, if the principal chips are socketed
these, too, can sometimes cause problems. Intermittent faults can sometimes
be corrected simply by pressing each of the larger chips into its socket. In some
cases it may be necessary to carefully remove the chips before replacing them;
the action of removal and replacement can sometimes be instrumental in wiping
the contacts clean.
Where a fault is permanently present and one or more of the supply rail
voltages is lower than normal, chip failure may be suspected. In such an event,
the system should be left running for some time and the centre of each chip
should be touched in turn in order to ascertain its working temperature. If a chip
that is not fitted with a heat removal device is running distinctly hot (i.e. very
warm or too hot to comfortably touch) it should be considered a prime suspect.
