HP Compaq Presario f700 Laptop died

My sister has the above mentioned laptop. Last month she brought it to me because the dvd quit working, I removed and reseated the dvd unit which then started working again. All is well until Monday this week, now you push the power button, the lights blink on, then right off again. No beep, no blip on the screen, nothing powers up.
No fans, HDD, nothing on the screen. I did try battery only vs. plugged in only combos. It does the same thing each way.

My question then is how to trouble shoot the power supply inside the laptop?
From where the power supply cord goes into the computer, then through the board that I assume differentiates between the battery and being plugged in, to the mother board? I can check the power brick with a multi-meter, but I really don’t know how to inspect a pcb Other than a visual inspection for corrosion or scorch marks.

I assume the power supply board inside of the computer simply because most problems with my desktop pc’s wind up being related to the power supply.

I did an online check, and the part is around $50.00, so I won’t be buying one to troubleshoot with. I have plenty of power supplies for desk top units.

Any online places to help me go through the steps to trouble shoot the laptop power supply from the input jack to the mother board pins??

Thanks.

If I can’t find a problem with the psu then I will assume it is indeed the mother board, but I didn’t find any obvious problems there either.

FWIW my HP laptop did the same thing. I took it to a PC repair place and it turns out the the problem was the port that the charger plugged into on the laptop. It had become either loose or cracked where it connected to the power supply from years of plugging the charger in.
It seems that the repair would be simple enough, crack open the case and soder the port where the connection is cracked or loose. I asked the guy how much to fix, as I really liked this laptop and he quoted me $200! I just stared at him for about a minute shocked that he thought anyone would pay that in this era of new $300 laptops.
I suspect that the shop owner was trying to pull a fast one. I really can’t see a repair like that costing more than $40 or so dollars. I might try to take it somewhere else. I was going to repair it myself, but can’t seem to get the case apart.
Also, it seems that if I could find a way to charge the battery independent of the laptop I could run on battery power alone.
Oh and one more thing. The way we determined that was the problem was pretty simple. When you plug in the charger a light on the laptop confirms that the unit is charging. We plugged it in and then wiggled the plug. The light went on and off. So, when the battery was dead and I plugged in the charger it would give just enough of a charge to start boot up. But any minor movement moved the plug in such a way that the connection was broken, so the computer would attempt to start, lose power and shut off. No beeps or anything.

Try the following:

-Remove the RAM memory (should be located through a little door on the bottom of the laptop that you open after unscrewing a screw or two)
-Try to powerup without the memory in place - it won’t boot.
-Reinstall the memory, taking care that it is properly seated.
-Try to power on again.

Lemme know how it works out. Yes, it’s really simple, but I give it around 75% chance of fully fixing your problem.

laptop power receptacles often break on the motherboard because of stress. You could test that with a volt meter with the back off the unit.

voltaire: Did all that, had the unit pulled completely apart so I could check the motherboard for any obvious problems,

obbn: Did check this, the plug goes in easy, and is a little loose, but the light stays on. My multi-meter needs a new battery so it will be another day or so before I can do any checks on whether the battery is charged or not.

Magiver: this is kinda what I am looking for, any practical how too diy checks to test the components of the receiving jack and the electronics on the board. I did find a site that showed me a fuse, but that was the only part they covered. As above, I need to get a psu (battery) for my meter, then get my sister to bring her expensive paperweight over again for me to test everything.

Over all, I have found no blown or swollen caps, no scorch, no broken wires, solder connections, loose connections, or cracked boards. The receiving jack board is separate from the mother board and has a pigtail leading to the mother board .

So I have to delve into the checking of individual components.