Re: A7V266-E slow to boot, (display something)?

In article <1147198830.268451.198120@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
saturnlee@xxxxxxxxx wrote:

My friend gave me a dead Asus A7V266E that has 2 leaky OST 6.3V 1000UF
capacitors. ( Instead of bulging at the top like many bad caps, the OST
leak the white stuff at the edge with no sign of bulging(hard to
see!!!). I check it using *** smith ESR meter, both are 0.08, still
within the acceptable range)

The board is also missing one of the ant-like capacitor next the ICS
94228bf chip(bule arrow). I just randomly pick any junk capacitor from
dead board and solder it( Though i know it is not the correct way to
fix it)

I replace OST(Red arrows) with 2 G-luxon 10V 1000uF just to see if the
caps are the cause of problem.

Now the mobo can boot, but it take about 18 second( From pressing the
switch to actually seeing something from the screen)

Before i replace all the OST cap, i would like to know
What cause the mobo to take 18-19 seconds to display something on the
screen? Because the ant-like capacitor or many OST bad cap or crappy
caps i installed or buggy BIOS version or jumper setting??
Is 18-19s normal for this board?

http://www.geocities.com/saturnlee/Asus/A7V266E/1.JPG
http://www.geocities.com/saturnlee/Asus/A7V266E/2.JPG
http://www.geocities.com/saturnlee/Asus/A7V266E/3.JPG

The ICS 94228 is the clock generator chip for the board.
http://www.icst.com/pdf/ics94228.pdf

When I saw the parts configuration around that chip, I
couldn't believe my eyes. But maybe people do stuff like
that.

The two tiny capacitors are part of some low pass filters. Their
purpose is to help the motherboard meet FCC emission standards.
(Some people, when they design a circuit board, make room for
the capacitors, by placing pads on the board to solder the
capacitor, but in manufacturing, the location remains blank.
If the FCC testing fails, the capacitors can be added at the
last minute.)

This document shows a typical implementation. The series damping
resistors (quad resistor pack) are 33 ohms. The series
damping helps maintain the signal quality at the very end of
the track. If a 10pF capacitor is populated after the resistor,
the low pass filter is at 1/(2*PI*R*C) or about 500MHz. It filters
the harmonics off the 33MHz PCI clock signals. If the capacitor
went missing, there might be a slight timing shift of the clock
signal, and a PCI slot, or a PCI peripheral chip on the
motherboard might experience a timing change.

http://www.intel.com/design/chipsets/schematics/252812.htm

PDF page 21 of the document, shows filtering on PCI clocks.
The CK_409 is a clock generator chip. The tiny caps you see damaged
on your board, could be equivalent to the ones shown on the
right hand edge of the schematic page. In the Intel schematic
page, they are labelled "10pF EMPTY", implying they are only
for emergencies, like failing the FCC testing. And 10pF is
a tiny value, something you aren't likely to find in your
spare parts bin. (Probably the smallest one I've got is about
22pF.)

That shouldn't slow down the motherboard POST. Those PCI
clock signals could well go to the PCI slots, and if you
find a particular PCI slot or slots don't work, then remove
the SMT caps you soldered in. If the caps you used are 0.1uF,
they would make an awful mess of the clock signals. If
you don't have any 10pF caps, or whatever value you get
by measuring an adjacent cap, I'd leave them blank.

Just a guess,
Paul
.

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