Clevo M670SRU Part 2

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Some of you may recall my earlier post about the charging (or lack of)
on this laptop. Here's an update, and a question.

I don't have the original adapter (19v 4.74A), so I'm running the
laptop off a beefy HP 19v 7.1A adapter.

1. With no battery fitted the laptop won't run off the adapter.
Press the power switch and the power light blinks once and that's all.

2. With a charged battery fitted and no adapter the laptop will switch
on and runs normally until the battery goes flat.

3. With a charged battery fitted and the adapter plugged in the laptop
will switch on and runs normally for as long as you like.  The battery
does not discharge from day to day.

Tests with an Avo confirm that the laptop is running off the adapter,
and is drawing about 3A.

4. Unfortunately the laptop never charges the battery; the charge light
never comes on.  I'm using an external charger to top up the battery at
the moment.

Anecdotally the laptop should switch on and run from the adapter
alone, thus indicating that there is a fault in the laptop.

But before I rip it apart I've heard rumours that running a laptop off
the "wrong" adapter can cause strange behaviour.

I think that if an adapter is the right voltage and is capable of
supplying the maximum current required by the laptop and battery then it
should work just as well as the original.

Does anyone here know different?

Re: Clevo M670SRU Part 2

The part of your post I left below is generally correct for AC adapters
that connect to the laptop with only a 2-wire connection (usually a
coaxial barrel connector).  However, if the laptop has additional wires
in it's connection, then it's completely proprietary as to how it and
the laptop work (some of the power supply circuitry is in the AC
adapter) and no generalizations can be made.

Also, Dell and perhaps others have managed to incorporate some type of
"communication" between the laptop and the power supply (even when the
power supply is only a 2-wire supply) and the laptop won't fully work
properly with a non-OEM (Dell) adapter.

nick wrote:
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Re: Clevo M670SRU Part 2

Somewhere on teh intarwebs Barry Watzman wrote:
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Yup, and I think there is a good chance that this is the problem.... As long
as the battery is fitted the laptop thinks that it's got a source of power
so boots, then actually draws power from the non-original PSU... Perhaps.

"Give a man a fire and he's warm for the day. But set fire to him and he's
warm for the rest of his life." Terry Pratchet, 'Jingo'.
Nota bene: 'Return to' email is very rarely checked, if at all. It's spam
city but is a req. of my NNTP providor.

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Re: Clevo M670SRU Part 2

~misfit~ wrote:

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Thanks guys.  I've asked a friend who has the same model to
check his adapter connector for any sign of a 3rd wire.

I believe Dell use a 3rd wire.  See

Barry, do you know of any specific examples of where communication
between the adapter and laptop is enabled over only the two wires
which are carrying the power?

I'm not saying it's impossible, just unlikely!


Re: Clevo M670SRU Part 2

nick typed on Thu, 11 Feb 2010 13:16:35 +0000 (UTC):
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Hi Nick! I was thinking in another direction than Barry or Shaun was. As
I was thinking that at best, maybe a fuselink has blown going to the
battery charger circuit. At worse, a chip or two has failed.

As for what Barry was saying... well you can modulate small digital
signals on a power line without problems (even analog ones if you would
like). So this isn't a problem. As you do have some leeway as for input

Another way it could happen is that the laptop could survive a very
quick power outage (even without a battery installed). But easier yet,
when the laptop is first turned on, you have many milliseconds to have
the adapter and the laptop to communicate with each other before
supplying the full load. The user won't notice that a few milliseconds
of a delay anyway to do this check. And if the laptop didn't hear the
right secret code in the beginning, could refuse to accept power from

Gateway M465e ('06 era) - Windows XP SP3

Re: Clevo M670SRU Part 2

BillW50 wrote:

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My friend has got back to me re chargers.  He has used a couple of
different chargers, neither of them original, with no problems.  The
schematics in the service manual show no trace of a 3rd wire, so it
looks like the charger control chip has failed.

Thanks for all the helpful input guys.

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