how annoying.. [IBM thinkpad]

[carl0s]

So I bought the replacement motherboard from eBay, and all seemed well with
the machine running for around 10 minutes.
I closed the machine and left it to recharge its battery. When I came to
switch on, it wouldn't fire up, and I could hear funny noises which I
suspect was the hard drive beign powered on/off at something like 2hz.

After a bit of playing, it seems that this board is now dead also, except
that on this one the power and activity (hdd) lights are flickering very
quickly, and about one-third brightness.

Could there be a logical explanation for what might be damaged? Perhaps some
kind of capacitor which is needed to hold a charge and allow it to power-up?
What can I test with just a multimeter?

I have since noticed that the PSU is over-rated, at 4.5amps instead of the
machines stated 3.5A, but I thought that the additional current was simply
not used. Could this have been the cause of the problem?

I have now tried a more closely matched thinkpad PSU (3.36A), and it does
the same.

thanks for any help.

 

[UncaJJ]

If you unplug the PS and take out the battery and then replace will it
turn on? I had something similar to that happen to my thinkpad (390X)

never got it fixed though

 

[carl0s]

If you unplug the PS and take out the battery and then replace will it
turn on? I had something similar to that happen to my thinkpad (390X)

never got it fixed though

nope, I've tried all permutations of that sort of thing.

 

[Dave D]

I have since noticed that the PSU is over-rated, at 4.5amps instead of the
machines stated 3.5A, but I thought that the additional current was simply
not used. Could this have been the cause of the problem?

No. As long as the voltage is identical and the current capacity is equal or
greater, it will be fine. The laptop will draw whatever current it needs,
and a larger capacity power supply is in fact a bonus- it *should* run
cooler and last longer.

I have now tried a more closely matched thinkpad PSU (3.36A), and it does
the same.

thanks for any help.

Laptops generally slow-charge the battery when powered up, and fast charge
the battery when powered off. This is because of the limitations of the
small power supplies. It sounds like something on the motherboard was
damaged while charging the battery, possibly the battery itself has an
issue- maybe that damaged your old motherboard? It's impossible to say
without proper diagnostic procedures.

You'll need some considerable experience with SMT rework, the necessary
tools and access to what are often specialist components if you are to be
able to sort this out yourself, a multimeter and a soldering iron aren't
enough.

Is there a light on the power supply? Does it dim when the laptop is
misbehaving? It sounds like the laptop is drawing too much current, or the
power supply voltage is too low.

Dave

 

[carl0s]

You'll need some considerable experience with SMT rework, the necessary
tools and access to what are often specialist components if you are to be
able to sort this out yourself, a multimeter and a soldering iron aren't
enough.

Is there a light on the power supply? Does it dim when the laptop is
misbehaving? It sounds like the laptop is drawing too much current, or the
power supply voltage is too low.

Thanks for taking the time to reply Dave. I have been considering buying one
of those SMT rework stations from eBay for some time.. but even so, I don't
know enough about circuits and transistors to really get anywhere. I don't
even know how to identify what most of these SMT components are. I'd love to
have a clue though..

There isn't a light on the PSU, no.

oh well. I've gone back to the eBay selling saying it's faulty, but perhaps
as you say it is the battery which has killed it

Wouldn't be so bad if I wasn't doing this for someone else!!

 

[Dave D]

There isn't a light on the PSU, no.

Perhaps you could come up with a way of monitoring the power supply's output
voltage while trying to power up the laptop? The voltage shouldn't vary by
more than a fraction of a volt.

oh well. I've gone back to the eBay selling saying it's faulty, but
perhaps as you say it is the battery which has killed it

Wouldn't be so bad if I wasn't doing this for someone else!!

Oh, it's always worse when it's someone else's appliance! Good luck.

Dave

 

[Mike Berger]

It sounds like there's a good chance that it was fine until you
messed with it. I hope you explain that to the Ebay seller too.

People complain if you sell something as-is when you insist that
it works, but then they want you to warrant their mistakes.

 

[carl0s]

It sounds like there's a good chance that it was fine until you
messed with it.

Well you could be right, but it seems at least a little unlikely. The PSU
is, or appears to be good, and everything else is onboard, including the CPU
and RAM. The only other possibility might be the battery, but I've never
heard of a battery pack having some kind of intermittant short through all
the cells (the battery, and everything else, was running ok for the ten
minutes.)

I hope you explain that to the Ebay seller too.

I told him it ran for 10 minutes, pretty much like I said here.

People complain if you sell something as-is when you insist that
it works, but then they want you to warrant their mistakes.

Sure, and it is an auction at the end of the day, but it's sold as working
and I'm not exactly trying to have him over. I have asked if I can meet him
half-way on a replacement, since he does have a few more up for sale.

 

[Dave D]

Sure, and it is an auction at the end of the day, but it's sold as working
and I'm not exactly trying to have him over. I have asked if I can meet
him half-way on a replacement, since he does have a few more up for sale.

Did you wear an antistatic wristband while installing it? Was it supplied in
an antistatic bag?

Dave

 

[carl0s]

Did you wear an antistatic wristband while installing it? Was it supplied
in an antistatic bag?

Dave

Yes and yes.