laptop motherboard remain power on

  • Thread starter Thread starter LS
  • Start date Start date
L

LS

Hi,
In a HP NX9010 when I plug in the power the LCD lamp is ignited without I
push the power button.
After when I power on, the laptop work fine.
When I press the power button to shutdown, the lcd lamp remain ignite and a
sound-stop led remain on.
Wher is the problem ?
I think the cause of the problem is one of the this chip:
MAX3243C
LM339M
MAX1632EAI
Someone can help me ?
thanks
 
"LS" said:
Hi,
In a HP NX9010 when I plug in the power the LCD lamp is ignited without I
push the power button.
After when I power on, the laptop work fine.
When I press the power button to shutdown, the lcd lamp remain ignite and a
sound-stop led remain on.
Wher is the problem ?
I think the cause of the problem is one of the this chip:
MAX3243C
LM339M
MAX1632EAI
Someone can help me ?
thanks
Click to expand...

MAX3243C = RS-232 interface chip
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1069

LM339 = Quad analog comparator
http://www.national.com/ds/LM/LM139.pdf

MAX1632EAI = Multi Output, Low-Noise Power Supply Controllers
for Notebook Computers .
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1660

I suspect none of those chips are involved.

The power for the backlight comes from the backlight
inverter. It must be switched on and off somehow, but
the three chips listed above don't necessarily have
anything to do with it.

This is an example of a controller chip for an inverter.
The SH pin can be used to switch the inverter on and off.
The inverter would likely be powered directly from the
battery, as the control chip has a very wide input
voltage operating range. I would try and trace the
control signals from the inverter, to get some idea
of what is at fault. It could even be a faulty
inverter for that matter.

http://pdfserv.maxim-ic.com/en/ds/MAX1895-MAX1995.pdf

Paul
 
Thanks for the information,
I test the parts on motherboard that remain on:
after a shutdown with XP or with power button pressed for some sencond
1 - the CPU fan stop
2 - the HD and CD activity stop
3 - I insert a postcard in the mini-pci slot and it show FFFF continuously
(this is the normal situation after the bios control it's ok)
4 - the power button led and leds next it are off
5 - one led next sound connector it's on
6 - the LCD lamp remin on (what's the chip that control the power to
inverter ? )

There is one or more than one chip to switch on/off the power on motherboard
?

Thanks in advance
 
"LS" said:
Thanks for the information,
I test the parts on motherboard that remain on:
after a shutdown with XP or with power button pressed for some sencond
1 - the CPU fan stop
2 - the HD and CD activity stop
3 - I insert a postcard in the mini-pci slot and it show FFFF continuously
(this is the normal situation after the bios control it's ok)
4 - the power button led and leds next it are off
5 - one led next sound connector it's on
6 - the LCD lamp remin on (what's the chip that control the power to
inverter ? )

There is one or more than one chip to switch on/off the power on motherboard
?

Thanks in advance
Click to expand...

I would suggest to you, that the Inverter board has a chip on it.
A single logic signal to that chip, controls the on-off state.
That is what the example Maxim controller chip has as its
feature - the SH signal shuts it off. You will have to examine the
Inverter, which should be packaged very close to the LCD.

The Inverter on your broken machine could be different from that,
and I am not an expert. I do not know all the mechanisms for
controlling inverters. It is always possible a MOSFET somewhere
on the notebook, controls the flow of power to the Inverter.

The Inverter connects to the LCD lamp. The Inverter converts
battery voltage (maybe 12VDC or slightly more), to 1000VAC or more
to drive the CCFL lamp. Either the DC voltage to the Inverter
is switched on and off by a power supplying circuit on the laptop,
or if a fairly smart chip lives on the Inverter circuit board,
like the example Maxim chip I showed you, then all that is needed
is a logic signal feeding the Inverter, to turn it on and off.

The Inverter may have a multi-pin connector on it, and that could
be where all the low voltage control signals reside. That is where
I would look for the control signal if it is present. There may
also be an analog signal on the same connector, to control the
intensity of the backlight. Of course, that intensity control
signal will not turn the lamp off completely, and the separate
logic level signal for on-off is what you are looking for.

Paul
 
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