HP G72 Laptop Won't Turn On

eww34445 · Apr 10, 2016

I have a HP G72-B62US Laptop that won't turn on. When plugged into the wall, the power button light will come on, but not the charging light on the DC Jack. And that's all it will do. The fan doesn't run, I don't hear the harddrive running, etc.

So, I have so far:

- Replaced the DC jack. Afterward, I have tested the AC adapter and the DC Jack with a multimeter, and am getting the correct output voltage.

- Replaced the motherboard. Purchased from reputable ebay seller, and looks as if they tested it.
(Note that this motherboard has a removable CPU)

- Hooked the HDD up to another computer. Works fine.

- Tried reseating RAM, booting with only 1 stick, and none at all.

- Checked CMOS battery. It is fine.

- Hooked up external monitor. No ouput

The only things that I can think of are that maybe the heatsink fan, CPU or LCD could be bad, but I have tested or replaced everything else I can think of.

Any help would be greatly appreciated.
Eric

Laptop_Nerd · Apr 10, 2016

Hi,

It seems like you've pretty much done all the possible troubleshooting steps that should have solved the issue. When the motherboard was replaced it should have already solve the issue. If it was the CPU chances are yes it may not boot up as well. Did you replaced the CPU as well when you replaced the motherboard? Also do try swapping the places of the RAM's or use 1 RAM stick from one slot to the other. And lastly, disconnect the ribbon cable that connects the LCD to the motherboard then connect the external monitor again and see if you'll get any display from it because this way the laptop thinks that the external monitor is the default display since the built in display is disconnected.

eww34445 · Apr 11, 2016

Laptop_Nerd :

I have already tried your RAM suggestions.

I tried what you suggest about the LCD cable, and it didn't do anything. The fan and hard drive don't even spin when you try to turn it on. Well, the power light is already on automatically when you plug it in, so hitting the power button doesn't do anything. Even holding it down for a period of time doesn't make the light go off.

No I did not replace the CPU or the heatsink/fan. I transferred them from my old board.

I guess I will get a CPU and try that. Do you think that if the heatsink fan was broken, would that keep it from booting?

eww34445 · Apr 22, 2016

So, I got the new CPU and a new fan for the heatsink, but the problem is still the same.

Currently, I am trying to just run a setup of only the motherboard, cpu, heatsink, 1 RAM stick, CMOS battery, and then the DC port and power button are plugged in. And I have an external monitor plugged into the VGA port.

The only part here that has not been replaced so far is the power button board, so I ordered one of those to see if that could be it.

tman1 · Apr 22, 2016

Internal monitor, external monitor - doesn't matter. A laptop can still power/boot up without any monitor and since yours isn't turning on, connecting an external monitor is a waste of time as a troubleshooting step.

While you wait for the power button board, if you can tone out the pins that go to the power button, you can short the two pins on the board to test. If it turns on, then it was indeed that board. If not, replacing it won't matter.

eww34445 · Apr 27, 2016

tman1 :

I got the power button board and the issue is still the same (power light comes on solid blue as soon as you plug in the adapter, without pushing the power button).

At this point, I have replaced everything, I think. I had replaced the DC power jack in January, but not since it broke this time, but that is the only thing left to replace. So I ordered one of those, and we will see.

If that doesn't work, I have no idea what to try next.

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HP G72 Laptop Won't Turn On

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