A7N8X almost dead?

  • Thread starter Thread starter Mads Hansen
  • Start date Start date
M

Mads Hansen

Hi group,

I'm having bad problems with my A7N8X Deluxe.

The system shuts itself down a few seconds after you turn it on.
Up till now the system has been rock-solid.

I've been away on holiday for three weeks, but the computer ran fine
for several hours the day before it crashed. The day it crashed, it
had been on for a few hours, and then turned off for an hour or two.
When turning it on after that, it crashed.

I have tried some different things:

- Running the system with only gfx-card, CPU and one block of RAM
installed, and no drives - didn't help.

- Changing the PSU - didn't help.

- Taking everything out of the case and putting it back in, checking
for bad contact in sockets, loose plugs, you name it - didn't do any
difference.

The BIOS speech report doesn't say anything.

As a last try, I started up the motherboard with no GFX-card, CPU or
RAM - just the bare motherboard.

Then the voice has time to say that the CPU is missing - it says it
two full times, and the third time it starts, but dies by the second
or third word in the sentence. It doesn't die at the exact same spot
each time - there is a word more or less spoken from try to try.

It doesn't help to unplug the sound.

If anyone has any ideas what's wrong, I would be very glad to hear
them!

Mads Hansen
 
Hi group,

I'm having bad problems with my A7N8X Deluxe.

The system shuts itself down a few seconds after you turn it on.
Up till now the system has been rock-solid.

I've been away on holiday for three weeks, but the computer ran fine
for several hours the day before it crashed. The day it crashed, it
had been on for a few hours, and then turned off for an hour or two.
When turning it on after that, it crashed.

I have tried some different things:

- Running the system with only gfx-card, CPU and one block of RAM
installed, and no drives - didn't help.

- Changing the PSU - didn't help.

- Taking everything out of the case and putting it back in, checking
for bad contact in sockets, loose plugs, you name it - didn't do any
difference.

The BIOS speech report doesn't say anything.

As a last try, I started up the motherboard with no GFX-card, CPU or
RAM - just the bare motherboard.

Then the voice has time to say that the CPU is missing - it says it
two full times, and the third time it starts, but dies by the second
or third word in the sentence. It doesn't die at the exact same spot
each time - there is a word more or less spoken from try to try.

It doesn't help to unplug the sound.

If anyone has any ideas what's wrong, I would be very glad to hear
them!

Mads Hansen
Click to expand...

That almost sounds like some onboard regulated voltage
isn't working properly. I mean, you did have crashing before
taking the system apart, implying that something was out of
spec.

It could be a protection circuit that is shutting off the computer.
In your test without the CPU, there is no CPU to shut the board
down, so only dedicated hardware circuits could be responsible.

If you have a stuck power switch, that might give you four seconds
before there is a power state change. The chip that interfaces
to the power switch, looks for the switch to be asserted for
four seconds, and perhaps that is what you are seeing. Try
disconnecting the case power switch. I've tested motherboards
by using a screwdriver tip to momentarily short together the
two pins where the power switch connects. You should drain any
static charge off the screwdriver tip, just before connecting
the screwdriver for a moment to the two pins.

The processor probably has an eight pin chip that senses CPU
diode temperature. If that chip has a problem, maybe it is
shutting down the board.

Similarly, there is probably an "AGP Warn" circuit, which can
kill the power to the board. Maybe it is malfunctioning.

Neither of those two circuits have time constants consistent
with your symptoms.

Do you see any visible damage to the circuitry around the
processor socket ? This would be the Vcore regulator circuit,
consisting of MOSFETs (three pins plus tab, soldered down to
board), toroidal inductors, and electrolytic capacitors. If
any of those show signs of physical damage, that might account
for the voltage being out of spec to the processor, causing
it to crash. Asus hasn't had a lot of trouble with
bulging or leaking capacitors, but take a look for them too.

Based on the testing you've already done, I'd be preparing to
RMA. A stuck power switch is the only other thing worth testing
for (by removing it, and using another switch, like the
momentary contact of a screwdriver tip).

HTH,
Paul
 
Hi group,

I'm having bad problems with my A7N8X Deluxe.

The system shuts itself down a few seconds after you turn it on.
Up till now the system has been rock-solid.

I've been away on holiday for three weeks, but the computer ran fine
for several hours the day before it crashed. The day it crashed, it
had been on for a few hours, and then turned off for an hour or two.
When turning it on after that, it crashed.

I have tried some different things:

- Running the system with only gfx-card, CPU and one block of RAM
installed, and no drives - didn't help.

- Changing the PSU - didn't help.

- Taking everything out of the case and putting it back in, checking
for bad contact in sockets, loose plugs, you name it - didn't do any
difference.

The BIOS speech report doesn't say anything.

As a last try, I started up the motherboard with no GFX-card, CPU or
RAM - just the bare motherboard.

Then the voice has time to say that the CPU is missing - it says it
two full times, and the third time it starts, but dies by the second
or third word in the sentence. It doesn't die at the exact same spot
each time - there is a word more or less spoken from try to try.

It doesn't help to unplug the sound.

If anyone has any ideas what's wrong, I would be very glad to hear
them!

Mads Hansen
Click to expand...

About two years ago there was a lot of problems with motherboards that
used power supply capacitors from one particular manufacturer in
Taiwan. The symptoms that you are describing are similar to the
problems that others were seeing. If one of the filter capacitors on
your motherboard is beginning to go, it would explain what you are
describing. You can do a visual check and look for leakage around the
caps or bulging and swelling. If that is the case, then you can order
a replacement kit from Homie. Look up Capman on the Abit newsgroup.
He's repaired hundreds of Abit boards.

Another possibility is that your fan tachometer, or the circuit that
reads it, is dying. You could try replacing the fan.

arnie
 
Based on the testing you've already done, I'd be preparing to
RMA. A stuck power switch is the only other thing worth testing
for (by removing it, and using another switch, like the
momentary contact of a screwdriver tip).

HTH,
Paul
Click to expand...

Thanks for your suggestions.
I tried shorting the power connectors, and the system starts up, but
shuts off again, as before.

I have also tried removing the battery and clearing CMOS, didn't help.

So I'm off to buy a new MB now - will deliver this one back, if I can
find the invoice, but can't wait for a replacement to arrive.


Thanks again,

Mads Hansen
 
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