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Inspiron 8100 no power

Posted: Fri Oct 12, 2007 7:27 pm
by ibleet
A friend of mine brought me her dead Inspiron 8100. She said it worked the night before and that the battery was fully charged. The next morning she took it to work and it wouldn't start, even when plugged in. She said the power light was lit, but as soon as she hit the power button, the light would go out, but no start. Then the light would not come on at all, whether it was plugged in or not.

First, I got another AC adapter to make sure that wasn't the problem. No help there. Then I took the laptop apart and reseated all the components...removed display, keyboard, ram, drives, video card, cleaned it and put it all back together. Still no power.

I'm thinking the motherboard is either bad, or somehow is not getting power from either the battery or the AC adapter to the motherboard. Possibly power button board or DC power board.

Any ideas on whats wrong, or ways to diagnose it?


Re: Inspiron 8100 no power

Posted: Sat Oct 13, 2007 3:49 am
by DMB2000uk
More than likely the motherboard went.

I know with my inspiron 5150, though it might only be a design flaw in this particular laptop, after so long of taking the laptop everywhere there is a pressure point on the motherboard that when pressed will cause the machine to not turn on at all. So maybe try smacking all over the base of the laptop while trying to turn it on? :rolleyes:


Re: Inspiron 8100 no power

Posted: Sat Oct 13, 2007 10:13 am
by ibleet
Thanks for the input Dan, I appreciate the help. Most laptops do get bounced around a lot, but not this one. I can count the number of times it has left my house on one hand, so thats not likely what happened to this one. And my friend only had it for a week when this happened.

I'm thinking more along the lines of a power surge maybe, which fried either the power button board, the DC power board, or the motherboard itself, or maybe all 3.

I'm gonna grab my voltmeter and begin testing today. I was hoping it would be easier, but it never is. :mrgreen:

Thanks Again Dan! 8)

Re: Inspiron 8100 no power

Posted: Sun Oct 14, 2007 1:09 pm
by ibleet
I took the laptop apart again, all the way down to the motherboard. Checking from the input jack, through the power button board, to the DC power board. No signs of a power surge anywhere. Reseated everything once again. This time I also reseated the power button and DC power boards. Checked for cracks in the boards...didn't find any. Tried your suggestion of bending the board a bit, and also jiggling the power cable at the sign of power whatsoever.

I checked both batteries...they have a button you push and 5 lights. The 1st battery showed fully charged at 5 lights. The 2nd battery showed 4 lights, so that one has a decent charge also.

So what I have so far is an AC adapter that works. I have 2 charged batteries. Yet I have no power to the motherboard. Not a single light comes on. I tried removing the drives and Ram and plugging it in, and there is still no sign of power.

My voltmeter mysteriously disappeared, so I'm waiting to borrow one from a friend. So now I just have to test to see where the power stops. I'm pretty sure the DC power board works, but I suspect that either the motherboard has a bad AC jack, blew a circuit, or maybe its something as easy as the power button board is bad.

Any insight or observations would be appreciated. I hope that someone has experience with laptops because mine is severely limited. I hate to put any money into this laptop when the max its worth is $300, but having traded it to a friend just a week ago, I feel obligated to get it working.

I did see a few deals on ebay for used motherboards, but I'm skeptical to use ebay and get burned.

Thanks for the help.

Re: Inspiron 8100 no power

Posted: Sun Oct 14, 2007 4:54 pm
by ibleet
I wish I weren't dominating this thread...

Ok, here are the readings so far...

input jack - 20v
power button board - 5v at the power button
DC power board - 20v

So, I'm getting power which eliminates the AC adapter as the culprit. Power thru the jack eliminates a bad jack or loose plug-in connection. I'm not sure if 5v at the button board is sufficient. I don't have schematics so I don't know what voltage values I should be getting at all points, but I'm going to check that next.

I just can't figure out why I have no lights at all when I have power, both from the input jack and the batteries. Anyone have any ideas? If you know anyone, or anywhere I can get some help with this issue, please let me know. Thanks.

Re: Inspiron 8100 no power

Posted: Sun Oct 14, 2007 7:00 pm
by ibleet
Fixed! Thanks! :)

Re: Inspiron 8100 no power

Posted: Mon Oct 15, 2007 6:03 am
by DMB2000uk
lol, sorry I couldn't be more help, but it isn't my field.

What was the problem then?


Re: Inspiron 8100 no power

Posted: Mon Oct 15, 2007 12:28 pm
by ibleet
Nps Dan, the most important thing is that you tried to help and I appreciate it!

After tearing it down one more time, I decided to completely remove the top plastics, aka the palm rest assembly. I needed to do that anyway to get access to test the DC power board with the multimeter. Removing this revealed that the DC power board was seating on a slight angle, and therefore wasn't completely tight or secure in the slot. I had reseated it twice previously, but without removing the assembly, it wasn't visible enough to see that the board wasn't going all the way down into the slot. So, I pushed the board down in straight and tight, followed by the video card, put it all back together, plugged it in and immediately saw power lights. I had to go into the bios and reset the time, then it booted up perfectly.

The big lesson to be learned is to make sure you tear the laptop down completely so you have good visibility. Its amazing the difference that can make in the end. It was nice having the multimeter to confirm that I was actually getting power to all the components and boards. All in all it was a good education for me.

Re: Inspiron 8100 no power

Posted: Wed Oct 24, 2007 6:15 pm
by orlandofl

I owe you a huge thank you. I have been w/o my 8100 for a couple of months. "Dead to the World". I have a new desktop, and wasn't "needing" my laptop until a few days ago. I have torn my laptop down in the past, but not as much as you recommened in your post. I found my problem, which happened to be the same as yours.

I was debating buying a new laptop 2 days ago, and actually had already paid Dell to fix my problem. The box was on the way when I found your post and tried looking for problems one last time. I realized exactly what you where trying to say while I was rebulding it - not looking for the problem. The dc power card had a very noticable snug fit, which wasn't there when I took it apart. After getting it all back together, i crossed my fingers and plugged it in. Sure enough, my power and battery lights came on.

You saved me at least $199, and if dell would have said my main board is bad, they would have charged and additional $299. If you live in the US, please send me your address as I would like to send you a gift card of some kind. Let me know what you like (stores, shopping, food, etc).

Thanks again

Re: Inspiron 8100 no power

Posted: Wed Oct 24, 2007 6:33 pm
by ibleet
I am smiling from ear to ear just knowing that this information was so helpful. That is all the thanks required. :)