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- compaq pc computer PW 505AA ,
November 7, 2013, 2:18 am
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Re: compaq pc computer PW 505AA ,
PW 505AA = Compaq Presario SR1410NX Desktop PC ???
The motherboard is P4GV-LA (OEMed by Asus). This particular
motherboard for sale on Ebay, has bulging capacitors around
the CPU socket, and won't last much longer. Symptoms
from this motherboard, could be crashing in the OS or in
the BIOS. Based on the vintage of motherboard and the
number of years it has been in usage, this is
probably a stress failure, rather than bad electrolyte.
Bad electrolyte eats through the capacitor tops quite rapidly
(takes around two years or less).
Check that you have not removed the ATX12V 2x2 cable,
with the two yellow wires and two black wires. That
must be plugged in, for the motherboard to work.
This connector is fitted next to the CPU socket and
just across from the string of aluminum electrolytic
capacitors. The connector has a lock latch, that
prevents accidental removal by bumping it. Make sure
the latch is engaged when reinstalling it.
The small square aluminum heatsink on the motherboard Northbridge,
is held down with wires. Some OEM motherboards (Dells ?) have current
flowing through the wires, and do a continuity check, to verify
the wires holding the heatsink are still in place. But you
might not hear any fans spinning, if the wires there were
open circuit. The "hook" hold down points on the four
corners of the Northbridge, those are known to not solder
well into the motherboard, The wrong metal is used for the
hold down, and they end up pulling out of the motherboard.
So you can check for that as well. That the Northbridge
heatsink is still properly attached. If the Northbridge
heatsink were to detach, and power was still available
to the motherboard, the Northbridge could overheat and
A test to indicate the CPU is powered and working, is to
remove the sticks of RAM, then power the system, and listen
for a pattern of beeps from the onboard piezo speaker. There
is a black disc speaker, near the front panel wiring header,
in the lower right corner of the motherboard. The BIOS
chip is right next to the speaker as well.
The procedure would be:
1) Power off the computer. *Unplug* the computer. Use
ESD precautions (wrist strap), remove the sticks of RAM
from their sockets. Store the RAM in an antistatic bag.
2) Plug in the computer. Power on at the back. Push the
power button on the front. Listen for a repeating error
code. Perhaps three beeps, a long silence, three beeps,
a long silence. If you hear any sort of beep pattern,
that tells you the CPU is running BIOS code successfully.
It actually proves a significant portion of the motherboard
works. Of course, it doesn't test RAM, because no RAM is
3) Push the button on the front of the computer, until it
shuts off. Switch off at the back. *Unplug* the computer.
Using ESD precautions, re-install the sticks of RAM. The
sticks of RAM are keyed, and only fit the RAM slots one
way. Make sure the RAM is fully seated, and the lock latches
end up in the upright position. Yiu usually hear a click
when the RAM is seated. You should not be able to see
the glint of the gold contacts on the DIMM, if it is all
the way down in the RAM socket.
4) The computer is now ready to use again. Plug in the power
cord again, and do your next test, whatever that is.
In situations where a RAM DIMM is shorting out the DIMM socket,
the motherboard will beep with the RAM removed, but not make
any beep noise when the RAM is installed. In which case,
you would substitute your spare RAM in the RAM slot for
For further help, tell us whether there are any beep patterns,
and when the beeps happen. A "happy computer" should beep
just a single time at startup. The beep in that case, is a
means of testing the piezo speaker, and proving the speaker
still works. If you hear no beeps, that is significant.
On home-built computers, the user probably hasn't hooked
up the speaker...
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