I really appreciate your persistance in trying to help with this problem,
but you must realize that I am fixing this computer as a friend (no pay!)
and hiring a competent electrical engineer doesn't come into the budget.
The person I am using has a degree in Avionics so I have to asssume he knows
what he is talking about, and I don't have the qualifications to question
his judgement. His multimeter was analog so it would be difficult to get a
2 decimal place accurate reading anyway.
There are two computers at their house. One is connected directly to the
modem. Everything works.
The other boots properly if there is no wireless NIC or modem in the PCI
slots on the motherboard. It does not boot if they are installed. I did not
bring a network cable to test if the onboard NIC worked. However, this
computer works properly at my house with the PCI cards installed, using
wireless or the LAN cable.
The only thing that seems different is their vs our router. Theirs was on,
ie powered up therefore broadcasting, but not connected to their modem. I
did not turn it off because I didn't think about it while I was there. I am
waiting on their decision as to what they want me to try next. My thinking
is to replace the router.
At my house both the wireless card and onboard NIC worked 100% of the
time.
The electrical guy who came with me tested the power to the motherboard
with
a multimeter and found approriate values according to the motherboard
schematics though did not test under load as he thought it unnecessary
since
the machine worked for two years,
Without a load, then multimeter numbers are inconclusive. An
informed electronics guy would know that. I said, "not provided are
multimeter numbers especially when computer is under maximum load."
If your electrical guy did not understand that, then he had
insufficient electronics knowledge. A load is essential. Otherwise
testing was time wasted. Also noted: “multimeter numbers contain
information that I would grasp and that you might not.”
eMachines does not provide schematics. Schematics do not provide
useful measurement numbers. "Good" means nothing. Any advantage from
the multimeter was lost without a full load and without posting those
numbers here so that hidden information is identified.
But again, I am repeating myself. I needed those numbers to be
helpful. A power supply that was defective 2 years ago can start
causing strange failures today AND would not be apparent without
measuring under load. Many assume a 5% variation. Assume 3.15 is
sufficient for 3.3 volts. However due to information I have provided
and how multimeters work, 3.15 means a defective supply. The minimum
number was 3.23. No schematic provides that number. Furthermore, a
number above that could still indicate another problem. But to learn
that, you must post all four numbers.
I am still not sure what you have posted. It does not work in their
house with NIC installed and no ethernet connection? Or it does work
only when ethernet cable is disconnected? Or they are using a USB
connection; not ethernet? Or it does not work unless both NIC and
wireless card are removed? Or it does work if NIC and wireless cards
are installed and connected, but disabled in the Network Connection
panel? Or it works except when ethernet cable is connected?
Continuing on that last assumption -
Ethernet cables have galvanic isolation at both ends. If
electricity from the router is causing computer failure, then, 1)
router has a power supply failure, 2) galvanic isolation in the router
has failed, and 3) galvanic isolation in the computer has failed. All
three must be defective. If you replaced the router and it worked,
you still have another failure - the NIC. Not likely.
Or NIC only causes problems when the wireless card also makes a
wireless connection?
Well, NIC operation is not in a list that can cause an OS lockup.
Did you mean network access locked (stopped) - OS still works?
If not asked in a first post, then I was remiss. What did system
(event) logs report?
Apparently you suspect an NIC. It is an eMachine. Therefore
download that diagnostic from the NIC manufacturer. What does the NIC
diagnostic report with ethernet cable connected, with cable
disconnected, and in both locations? If the NIC is onboard, then
locate the NIC's manufacturer name and chip number. Then find that
diagnostic.
If the router did fail on its ethernet cable, then so did the
computer's NIC. Two extremely unlikely failures? Either both have
failed and must be replaced, or neither creates a computer freeze.
So what do system (event) logs report? Again, text is important.
But numbers are essential. Those error messages without numbers may
be useless. And the most important messages are often only ones that
mean zero to you.
Computer has classic symptoms of a defective supply system. Yes, a
system which is more than a supply. Supply may be only just starting
to cause computer failures, and identified using a multimeter with
computer under full load. If problem is traceable to the NIC, then
NIC diagnostic will confirm that (with and without cable connected) or
provide information that identified what makes the NIC look defective.
