Dead motherboard restored

  • Thread starter Thread starter pjdd
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pjdd

Last week, in a thread started by someone else, I gave an
account of how I assembled my first PC entirely from scrap
parts, including dead CD-ROM drives and HDDs. It reminded me
of an idea that had been at the back of my mind for quite
some time. First chance I had, which was today, I tried out
the idea and restored a dead motherboard to life without too
much trouble. Just thought I'd share.

Two years ago, a customer was unfortunate enough to have his
computer struck by lightning less than 48 hours after I
assembled it for him. The computer wasn't even plugged in to
the mains, and lightning entered the ethernet port via a
neighborhood gaming network. The ethernet chip was literally
blown up and the mobo was dead. (I replaced the mobo at cost
price). Picture at
http://s48.photobucket.com/albums/f...rent=Blown_chip.jpg&refPage=&imgAnch=imgAnch1

I'd been wondering if the problem was localised at the chip,
and what would happen if I removed it. A quick probe with a
multimeter today showed that something was shorting the 3.3V
line to ground. I downloaded the datasheet of the Realtek
RTL8201BL chip and identified the three power supply pins.
Nothing changed when I desoldered pin No.48, one of the
digital supply pins, but The short on the 3.3V bus
disappeared when I desoldered pin No.36, the analog supply
pin.

I installed an Athlon XP 2000+ processor discarded by another
customer, inserted a 256MB stick, and plugged in a repaired
300W PSU. I briefly shorted the power-on pins with the tip of
a flat-blade screwdriver and voila ! the BIOS beeper beeped
and the CPU fan turned on.

I turned it off, connected an old 14-inch monitor and turned
it on again. Yes, I had a normal POST screen. The next step
was hooking up a spare 40GB hard disk with a basic Win98SE
already installed. It booted up beautifully and began
searching for drivers.

I now have a working Biostar M7NCG-400 motherboard minus the
onboard network interface. It uses the well-known nForce2
chipset with GeForce 4 MX graphics which is good enough
for most applications except serious gaming. I think I'll use
it to replace my daughter's 450MHz Pentium 3.
 
I downloaded the datasheet of the Realtek
RTL8201BL chip and identified the three power supply pins.
Nothing changed when I desoldered pin No.48, one of the
digital supply pins, but The short on the 3.3V bus
disappeared when I desoldered pin No.36, the analog supply
pin.
Click to expand...
I now have a working Biostar M7NCG-400 motherboard minus the
onboard network interface.
Click to expand...

You made a repair beyond the ability of 95% of the computer shops.
 
Norm De Plume said:
You made a repair beyond the ability of 95% of the computer shops.
Click to expand...


Ability? or efficiency?
This kind of repair is only feasable by home users. If I was the shop, I
should have to charge the customer for searching the defective part(s),
remove and/or replace it, testing. As a professional, I should have to find
and install a replacement part (customers do not accept the argument "it's
not worth to...). And on top, the customer will expect some kind of warranty
on my repair!
Now calculate the price and compare with the value of this (old)
motherboard, that you could buy on Ebay for 10 $ or less...
 
You made a repair beyond the ability of 95% of the computer shops.
Click to expand...


I doubt any significant portion of the remaining 5% that
"might" be able to find the fault, has actually done such
repairs.

As another poster pointed out, rightly so. A shop would
typically have more than one hour of bench fees for
something like that, multiple times the value of the board
already.

Fortunately for the OP, Realtek is better than some about
providing datasheets. The M7NCG-400 is a nice little mATX
board, especially considering how little it cost in it's era
but then that also weighs against the potential repair costs
at a shop.
 
I'd agree with everything said by EIJerid and Kony - if I
lived in a place like the US, but values and practices are
somewhat different where I live.

Here, I could build a system based on the old parts I
mentioned and sell it for a good price, but that's not the
point : I decided long ago to enjoy my work and not to
concentrate on getting rich or weigh everything against the
monetary returns they generate.

I could've been far richer than I am now, but I work at home,
have a very small staff and can truly call my time my own. I
enjoy sipping tea and chatting with a client for half an hour,
working out things to *their* best interest - we often become
good friends. (I generally avoid doing anything for the
government no matter how lucrative the financial rewards,
unless they specifically need my expertise).

I'm aware that I may not be able to survive this way in some
countries, but this is here, and not there. And I'm having a
lot of fun. And the satisfaction that comes from doing
something like this is priceless.
 
I'd agree with everything said by EIJerid and Kony - if I
lived in a place like the US, but values and practices are
somewhat different where I live.

Here, I could build a system based on the old parts I
mentioned and sell it for a good price, but that's not the
point : I decided long ago to enjoy my work and not to
concentrate on getting rich or weigh everything against the
monetary returns they generate.

I could've been far richer than I am now, but I work at home,
have a very small staff and can truly call my time my own. I
enjoy sipping tea and chatting with a client for half an hour,
working out things to *their* best interest - we often become
good friends. (I generally avoid doing anything for the
government no matter how lucrative the financial rewards,
unless they specifically need my expertise).

I'm aware that I may not be able to survive this way in some
countries, but this is here, and not there. And I'm having a
lot of fun. And the satisfaction that comes from doing
something like this is priceless.
Click to expand...

Fully agree!
I also like to repair "old stuff", whatever it might be, just for personal
satisfaction and maybe development.
But I understand that a company or businessman has other concerns, one of
them being financial return.
 
ElJerid said:
Fully agree!
I also like to repair "old stuff", whatever it might be, just for personal
satisfaction and maybe development.
But I understand that a company or businessman has other concerns, one of
them being financial return.
Click to expand...

Yes, I mentioned only personal satisfaction, but while I do
not at all disagree with the points you made about business
concerns regarding financial matters, the knowledge base and
diagnostic skills accumulated from such "indulgences" have
also proved invaluable many, many times when doing more
business-oriented work.

And not only in repair work, but also in developing new
designs, such experiences help with avoiding pitfalls and
reliability issues.

Anyway, my purpose in posting that bit of recent experience
was simply to share a rewarding moment. And if it serves in
some small way as an inspiration to a less experienced
enthusiast or entrepreneur, that would make it a time well
spent.
 
ElJerid said:
Ability? or efficiency?
This kind of repair is only feasable by home users. If I was the shop, I
should have to charge the customer for searching the defective part(s),
remove and/or replace it, testing.
Click to expand...

I can understrand the economic impracticality of this diagnosis/repair,
but I do mean it's beyond the skill level of 95% of the computer shops
in the U.S.
 
I can understrand the economic impracticality of this diagnosis/repair,
but I do mean it's beyond the skill level of 95% of the computer shops
in the U.S.
Click to expand...


Of course it is, computer shops aren't meant to handle this
kind of problem, as with most technicians in other fields
they are trained to replace entire subsystems rather than
discrete component level repair.
 
Yes, I mentioned only personal satisfaction, but while I do
not at all disagree with the points you made about business
concerns regarding financial matters, the knowledge base and
diagnostic skills accumulated from such "indulgences" have
also proved invaluable many, many times when doing more
business-oriented work.

And not only in repair work, but also in developing new
designs, such experiences help with avoiding pitfalls and
reliability issues.
Click to expand...

So true. And it comes full circle on the comment above about financial
concerns, in that such 'indulgences' can result in new businesses as
well as new methods and design ideas. Its an expensive luxury but can
be very productive for those that afford it.


NT
 
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