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8890 AC Adapter Question

post #1 of 4
11/27/05 at 1:20pm
Thread Starter 
I'm having intermittant problems with my 8890 ac adapter. On rare occasions, it simply shuts off (green light goes out and no power goes to laptop). Typically if I pull the plug, let it cool down a little bit, it works fine again. I've sent it in for repair once, but it was sent back since the technician couldn't find a problem with it (as I said, it happens rarely and typically only after its on for a hour or two).

So, I'm now thinking of purchasing a new adapter. The one I have is labeled 130W, but the new ones that are for sale are 120W. I'm also considering adding a second hard drive and I always run with other accessories, including multiple monitors and am worried that 120W wouldn't be sufficient. I've also seen similar ac adapters for sale for other Sager models that have the same voltage and 4 Pin DIN connector with higher wattage (e.g. 7620/9860 with 180W and 9980 with 220W).

Will these higher wattage adapters work with the 8890 or would you recommend I just stick with the 120W adapter for the 8890?

Thanks!
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post #2 of 4
11/28/05 at 12:32am
You need to be concerned with how many Amps are provided by the AC Adapter as well. The 8890 motherboard uses a 7 Amp fuse. Although I use the 9 Amp 9860 AC Adapter, it requires soldering in a 10 Amp fuse.
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post #3 of 4
11/28/05 at 1:39am
120W is the correct spec for the 8890 dude.
The laptop draws about 95W with 25W going to the battery recharge.
I have a pair of fully spec'd 8890 an all my AC adaptors are 120W.

As to the shutdown, it sounds like the switching regulator is stuffed.
You can extend their life by following this procedure when powering them up:

To turn on:
make sure AC adaptor is NOT plugged into wall socket.
plug DC connector into laptop
plug AC cord into power brick
now plug AC plug into wall socket (and for those that have a wall socket switch like here in Australia, turn on the power switch).

To turn off (reverse the procedure):
(Turn off wall socket if you have such a switch)
Remove AC plug from wall socket
Remove AC plug from power brick
Remove DC cable from laptop.

The reason for doing the above is to minimise inrush current. Because of the way switching power supplies work and the high DC currents involved when you apply a load to a switch mode power supply the current feedback mechanism kicks in chopping more of the AC line into the DC output stage. Like all control systems you can never get a perfect response so overshoot/undershoot happen. This stresses the DC side of the switch mode power supply more than it has too. By having the load already present (ie. the laptop is plugged in before AC is applied) the stress is a lot less on the components.

Apply the AC after you plug in your laptop.
Remove AC before you unplug your laptop.
Your switch mode power supplies will thank you
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post #4 of 4
4/5/06 at 12:36am
Quote:
Originally Posted by aussie
As to the shutdown, it sounds like the switching regulator is stuffed.
You can extend their life by following this procedure when powering them up:
/snip
Your switch mode power supplies will thank you
Good tips! I thank you as well!
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