Hp compaq nx7300, power problem.

Hi,

I have got an hp nx7300 notebook that does not start.
-If I power it with connected AC/DC and connected battery nothing happens.
-If I power it with connected AC/DC and disconnected battery nothing happens.
-If I power it with disconnected AC/DC and with connected battery - power
led turns green, charging led blinks 7 times orange, one time green and one time orange and then both (power and
charging) leds turns off.

I disassembly device.Tried to remove memory,hdd,dvd rom,wi-fi and modem module but same problem.
I visualy inspect motherboard ,everything looks non broken or burned.
I worked some measurements trying to find some short ciriut ,did not find anything unusually.
On the power jack on the device I have 19,85 volts beetwen plus and minus and have 6,5 volts on id (midle) pin.
I have same volts on power connector no matter if battery is inserted or not.
I also tried to run it with another AC/DC but it also didn`t work.

any suggesstion is welcome
best regards
cole

Take a closer look to charger and his power mosfets,but try reset bios first.

AC / DC adapter original?
voltage on pins 1-3 and pin2 of Jack1
voltage of L32 and L24

Hi

Here we go.
Tryed to reset bios with holding power button more then one min. with and without battery.
Tryed with pulling out bios battery.No changes.
AC/DC adapter is orginal (also tryed other one, also orginal)

Jack1
from left to right (gnd probe of instrument I attach on gnd housing of device)
at pin 1 = 19.8 V
at pin 2 = 6.5 V
at pin 3 = 19.8 V

at L24,L32 no voltage if instrument gnd probe is attached on gnd (housing)
if positive instrument probe is attached at pin 1 or 3 at jack1 I have this:
at L24 = 19.8 V
at L32 = also 19.8 V

cole2hr napisał(a):if positive instrument probe is attached at pin 1 or 3

Please measure all the voltage in reference to ground only.
If no voltage on L24 and L32, check the voltage on Q6 (gate pin 4 and drain pins 5-8).

ok, understand
to ground
-L24 and L32 no voltage
-Q6:
gate pin 4=6.5 V
drain pin 7,8=19.8
source pin1,2=19.8

cole2hr napisał(a):-Q6:
gate pin 4=6.5 V
drain pin 7,8=19.8
source pin1,2=19.8

It is good. Now, please check the voltage on Q10 (gate pin 4 and source pins 1-3).

ok,
-Q10:
source pin 1-3 = 19.8 V
gate pin 4 = 10.4 V

5-6-7-8 pin voltage of Q39
voltages on pins 19, pin21, pin 31 of U31

-Q39:
pin 5-6-7-8 = 19.8 V

-U31:
pin 19= 0V
pin 21= 5V
pin 31= 5V

you can also check, before,

adp_pres , on pin 1 u503

-U503

pin 1 = 5V

voltages pins 4 of U31

-U31
pin 4 = 5V

Did you checked the correct pins? Counterclock starting from the small dot near the number one pin?

If yes, it seems that 3volt linear regulator is out of service, and the reference 2 volt on pin 4 is at a wrong value, maybe for a defective u31

Hello,again

I´m pretty shure that I correctly count pins.
I take a photo (attach) please rename u31 tps51120.zip to jpg
It is little hard for me since I dont have any manual (missing few points) and for shure I´m not expert as you are guys.
Thanks

//Please attach pictures as shown below

No, you're wrong.

Pin must be counted in counterclockwise mode, starting from the white dot that is pin number one.

What you signed in the picture as pin 31, is in fact pin 2, and so on.

cole2hr napisał(a):I´m pretty sure that I correctly count pins.

No you are wrong. As @linears4 said

linears4 napisał(a):Pin must be counted in counterclockwise mode, starting from the white dot that is pin number one.

picture posted by gathor, is in bottom view. so pay attention.

I definitely messed up.To make matters worse I took tps data sheet and I saw a picture that gathor posted and inconsiderate I made mistake.Because of this mistake you should throw me out from the forum.Sorry
Now I made it again.