# Hp Compaq NX7300 problem



## raptornexus (Jul 12, 2009)

Hi up until recently my laptop has been working fine....the other day it would only start on battery and not on mains.I thought it was the power lead as its gone in the past and ive had to buy another one.Anyway laptop works fine on battery but not on mains lead.I cant use it now as battery is flat and i cant charge it...i know mains lead is ok as ive had it tested...ive tried removing battery to see if it will start up on lead only but to no vail...anyone have any ideas please? many thanks.


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## Madcatz (Apr 15, 2008)

if the ac adapter tested fine and is putting out the right amount of volts, then theres only two things that affect charging and power. First is it could be a bad dc-in jack, or it could be a bad motherboard. The only way to test that is to unplug the dc-in jack from the motherboard (if its not soldered on) plug the ac adapter into that and then test the voltage at the pins that plug into the motherboard.


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## raptornexus (Jul 12, 2009)

Madcatz said:


> if the ac adapter tested fine and is putting out the right amount of volts, then theres only two things that affect charging and power. First is it could be a bad dc-in jack, or it could be a bad motherboard. The only way to test that is to unplug the dc-in jack from the motherboard (if its not soldered on) plug the ac adapter into that and then test the voltage at the pins that plug into the motherboard.


its soldered in


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## Madcatz (Apr 15, 2008)

then next thing i would suggest to do is remove everything you can, hard drive, battery, dvd drive, unhook the mouse, any cables you see under the keyboard, leave only the ac adapter, cooling fan, and power button plugged in and try and power it on that way. 

That may not do anything considering it could run on battery but not ac power. How was the ac adapter tested? with a volt meter? if so was the volt output steady and not fluctuating and within 1/2 a volt of its rated volt ouput?


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## raptornexus (Jul 12, 2009)

Madcatz said:


> then next thing i would suggest to do is remove everything you can, hard drive, battery, dvd drive, unhook the mouse, any cables you see under the keyboard, leave only the ac adapter, cooling fan, and power button plugged in and try and power it on that way.
> 
> That may not do anything considering it could run on battery but not ac power. How was the ac adapter tested? with a volt meter? if so was the volt output steady and not fluctuating and within 1/2 a volt of its rated volt ouput?


ok ive tried all of the above....tested ok with multimeter,was within 1/2 volt of rated volt output,on adaptor and at the board but still wont power on


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## Madcatz (Apr 15, 2008)

sounds like your going to need a new motherboard then. You can get the part number from a sticker that is normally under the memory dimms. be something like 416030-001


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## raptornexus (Jul 12, 2009)

Madcatz said:


> sounds like your going to need a new motherboard then. You can get the part number from a sticker that is normally under the memory dimms. be something like 416030-001


why would that be when it works fine off battery?


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## Madcatz (Apr 15, 2008)

since you can't power it from the dc-in jack and the jack is soldered onto the motherboard. No power from the dc-in like yours is very simple, can be the ac adapter, dc-in jack, or motherboard. You had the adapter tested and it worked, the dc-in and motherboard are together.

Which means the only way to charge the battery and actually use the laptop is externally from your laptop. Could probably use a docking station if there is one available for your laptop. You could try and find someone to solder a new dc-in jack onto it, but most people won't do that anymore.


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## jankro (Aug 5, 2009)

I had a NX7000 that just come in for service with a similar problem.
1. would not start on battery
2. on AC, the charging light flickered, would not start
3. tested a HP 120W smart power, lights flickered and it would boot, but smelled like burnt.

I took it apart and on the bottom side of main PCB, right next to the DC jack, a SMD condenser had burnt on one end (C 12).

Both power supply's were tested on a working HP and both worked correctly and put out voltage within 0.05V of each other.
So, this would make me think that the condenser was bad, maybe shorted.

I have to try to find a replacement and see what happens.

-Jan


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## jankro (Aug 5, 2009)

I can now answer myself ;-)

I replaced the SMD capacitor and now the laptop charges and starts right up like it should. ray:

Hope this helps someone with a similar problem.

-J-


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## rzwajar (Sep 15, 2009)

jankro said:


> I can now answer myself ;-)
> 
> I replaced the SMD capacitor and now the laptop charges and starts right up like it should. ray:
> 
> ...


Funny enough I have the same problem described here.
However I would like to know which cap and what is the value.
Do you maybe have a circuit diagram and layout?


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## jankro (Aug 5, 2009)

No, sorry I do not have a diagram. Diagrams for laptop mobo's are as rare as a flying hippo ;-)

However, you have to remove the motherboard completely from the laptop housing, since this cap is located on the top side of the pcb.

It is located very close (less than one inch) from the DC jack.
In my case it was obvious which part was in question, sice the PCB was black from soot next to the cap. It is not a polarized cap and it is not critical about value. Physical size was 3.14mm x 1.7mm (approximate) .
If I remember correctly, I used a cap from another laptop mobo that I had and it was approximately .5 to 1 microfarad.
On my earlier post I mentioned that it was C12.

Hope this helped.

-Jan


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