Latitude C400

Question

I have recently seen four C400 laptops with the same fault.

When a battery is inserted into the laptop the unit will not work. The power led on the power supply slowly drains away. With the battery removed, the laptop works fine. Insert the battery again and off it goes. It's not until the battery has been depleated that we notice this has happened as it runs fine on its own power.

I have called Dell and they say this is not a common problem with this model. I have a nasty feeling this will keep coming up!

Dell advise that the power regulator may be faulty and that a new motherboard is required to repair the fault.

Has anyone else had this problem?

Jonathan Ilott · Answer

And now another, this makes 5 now? Are we alone?

Jonathan Ilott · Answer

Now 6 - come on fellow dell community folk, shorly we are not the only ones affected by this?

Karell · Answer

Jonathan, Thank you for using the Dell Community Forum. Have you tried upgrading the systems to the latest bios revision?

Jonathan Ilott · Answer

We have not tried to update the bios, did not see how this would affect the pc as it is hardware related and happenes long beofre the pc has loaded its bios. Do you know of a particular fix in a newer bios revision that may help?

Delboy 352 · Answer

I also have the same problem with one of our Dell Latitude C400's. We have a number of these laptops in the company and have not come across this problem before. I have tried 3 x different power adapters with the same result. I am off to try a different battery, but will be ringing Dell to get the problem fixed if it is not the battery.

Karell · Answer

Jonathan,

The latest bios A11 fixes an issue with the battery gauge and some power management issues.
So, it is definitely worth a try to upgrade the bios.
If that does not work I would try another battery to see if you still have the same problem.
If another battery still causes the problem, then try getting the motherboard replaced on one of those
systems to see if it helps.

Jonathan Ilott · Answer

It's not the battery. Something goes on the motherboard. We now have replaced 4 motherboards and all are now ok. One thing we have noticed is that some (NOT SURE IF ALL) were running 90 watt psu's, same as the c640's use. Dunno if this has caused a problem? You can tell um by the grey connector.

Delboy 352 · Answer

Agree it is probably the Motherboard, but from previous experiences with Dell, they will always exhaust every option, and in this case would invariably say 'Have you tried another battery?' They would finally come to the same conclusion as we both know, that the Motherboard needs changing!! Cheers for the feedback.

Delboy 352 · Answer

Tried the A11 upgrade with same result. Will try battery tomorrow, but probably have to ring Dell.

Karell · Answer

Jonathan,

Yes, using the 90W power adapter could more then likely cause a problem.
Here is some information from the system docks.
---------------------------------------------------------------------
The Latitude C400 requires less system power for functionality. Because of this, the C400 ships with a new style of AC adapter. While the Latitude C400 is backwards compatible with existing Latitude C-series AC adapters, the new C400 AC adapter is not compatible with other system. The following are a few changes that make the adapter unique:

Changes to adapter tip to prevent usage on other Dell systems
55W output on the C400 AC adapter vs. 70W output of existing Latitude power supplies
New wraparound plastics with a Velcro strap for more compact & convenient storage
---------------------------------------------------------------------

The above info states that the system is backward compatible with a 70W adapters.
But, I could not find any information on what would happen if you used a 90W adapter.
I wonder if the additional 20W is what is causing the problem?

enine · Answer

Without going into a long post about Ohms law a 90w adapter will not feed 90 into a laptop that was designed to use a 55w adapter. The current (and therefore wattage) are dependant upong the load when the voltage is held constant. The wattage rateing on a power supply is the maximum amount it is capable of supplying. Basically the C400 will draw a max of 55w and a higher wattage p.s. can't 'push' more watts to a device.
I have used my c400 on over a dozen different dell supplies both for the c400 and the bigger lat's and haven't had a problem.
I can say there is slight difference between the two supplies. I have a laptop safe invertor and three different Compaqs, an IBM and my C400 have all worked fine from it buy my wife's Inspiron 1100 will not. I'm guessing the higher wattage power supplies do not filter the power as much as the smaller one and the compaq's and IBM's so maybe the C400, being designed for cleaner power, was more vulnerable to a surge/spike that made if through the bigger supply.

Jonathan Ilott · Answer

Thanks everyone.

So Dell, what is your verdict ?

We now have had a further two more failurers. Only one of these was using a 90w psu. the other being a 70 watt.

I will advise my company to use 55wat psu's on C400's in future to be safe.

Karell · Answer

Jonathan,

I recently asked an engineer a question along the same line.
A D600 includes both a 65W and 95W adapter, one for the system, and one for the docking station.
The engineer stated the system would work fine with the 95W adapter and it actually charged the battery faster.

The C400 is fully compatible with the C-dock docking station which uses the 90W adapter,
so it should also work with the 90W adapter.
As to whether the 90W adapter is not filtering the power correctly as it comes in, that
is something that would need a lot of testing to demonstrate.
Another thing to considered is maybe there was a bad batch of motherboards.
Were all the systems purchased around the same time frame?
Power spikes could definitely be a problem.
Do you have any way of testing to see if that facility is creating power spikes?
There has got to be a common thread between all the systems that are failing.
Have all the systems that have failed been used in the same area or facility?
Were all the system that failed purchased around the same time?
Is there certain hardware or a device that all these systems have been attached to?

Locked Topics – Laptops General

Latitude C400

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