On 2011-07-12 17:06:09 +0200, mike said:

Kripton wrote:
On 2011-07-12 13:51:41 +0200, "Allen" said:


Hi all


It possible testing, with a multimeter, electronic components, resistor,
integrated circuits, on a laptop motherboard?


Thanks

Regards

main failure on a motherboard is the capacitors leaking
you need an esr meter to test them
a multimeter cannot do that

you can get esr meter schematics free and commercials here :
http://kripton2035.free.fr/esr-repository.html

regards,

I think your heart's in the right place.
What you said isn't wrong.
BUT
In the spirit of educating the OP, it might lead to a less
efficient and more expensive solution.

Assuming that the OP has the expected senses for a primate,
"leaking" caps can be diagnosed with only one good eyeball.
Bad caps can also bulge. That too can be diagnosed by eye.
Bad caps with high ESR can get hot. That can be diagnosed
with a finger...being careful not to burn yourself.

I did a bunch of experiments with a TDR system measuring ESR.
I had mixed results in-circuit. There's just too much other
stuff affecting the reading...like other caps in parallel.
Getting the caps out without hurting them or the board is a
problem.
Anybody with the equipment to do it safely would not have
asked the question in the first place.

An easier test is to put an oscilloscope on the power bus
and look for spikes. So, I'd recommend a cheap used
oscilloscope LONG BEFORE recommending an ESR tester.

IN-circuit testing of any component is iffy unless you know
the circuit. NOT the typical circuit...the EXACT circuit.
That info is typically unavailable. I can't count the times
I chased my tail on a problem because I assumed that the
designer had done something reasonable.

I'll try to be respectful of the OP, but the way the question
was asked suggests that he hasn't much chance of fixing the
system. Given detailed symptoms, he might be led thru
some simple diagnostic procedures. He might get lucky.
Once you get past the broken solder connections on the power
supply socket and blown fuses and shorted diodes, there ain't
much to be done by the amateur with no (appropriate) test equipment.
Just accessing circuit nodes on both sides of a board that
has connections everywhere and heat sinks bolted to the infrastructure
is problematic.

Even if you find the bad part
there's the problem of acquiring one and replacing it without
breaking something else.

Given the complexity and throw-away nature of today's products, I've come to
the conclusion that it would take less time and effort to get a part-time job
slinging burgers and use the extra income to buy a new device.

I don't care for the advice to buy a new board on EBAY.
The most likely reason for ANY device to be sold is that it no
longer works properly. That goes triple for an anonymous market
like EBAY. Sure, there's lots of good stuff sold there...but the
stuff that's guaranteed good isn't gonna be cheap. The rest is
a crap shoot.

hello
on my web site I have collected a lot of schematics of esr meters (and
other testers)
most of them cost nothing using scopes as you describe
or using very easy to find and cheap components to adapt to a multimeter
take a look at the method described there
I also give links to commercial esr meters, for those who dont want to
make it themselves...

http://kripton2035.free.fr/esr-repository.html

best regards,

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Kripton