Notebook Power System Introduction & Troubleshooting-Part2

2. Power plan introduction :
By now we have learned how NB power is generated and
why it must be done in a specific sequence. You might start
o wonder, “What is other Power application?” In the
ollowing section, I will show you the power consumption of
all devices in a NB. You will learn:

 

2.1 Power budget block diagram
2.2 NB power application
2.3 Multi–power device

 

2. Power plan introduction :(cont’d)

Create a NB power system with fixed procedure, so
we can know the power budget of all devices from the
power plan procedure .
Design

a. Power budget :

We must first know the power category and
consumption of all devices, and then we can start to
define the SPEC of power.

b. Power application :

After power SPEC was defined, we need to confirm the
timing & sequence when power is turned on. And
separate them with S5,S3,S0, etc. for the purpose
of power saving.

2.1 NB (Yuhina) Power Budget Block Diagram

 

2.2 NB power application :
2.2.1 3D3V Device :

3. No power troubleshooting
No power define :
No power means when the power button is pressed, the power
LED is not turned on, and the system is not booted. We can
separate no power in four kinds of states :

3.1 No power debug notice & sequence
3.2 No DCBATOUT or short to GND
3.3 S5 Power No Good
3.4 Power on logic No Good

If power system is good & power LED turned on, but the system
still N.G., it means the system is “No work”.
You must follow the “No work debugging” process to troubleshoot
the problems.

3.1.1 debug Notice :
3.1 No power debug notice & sequence:

For safety’s sake, please use adapter to supply the
Notebook power when you execute the debug process .
• This debug procedure can only cover about 90% no power
Problems.

3.1.2 debug Sequence :



3.2.1 Symptoms:
3.2 DCBATOUT short to GND :

• There is no any response when the power button was pressed and
adaptor was already inserted .
• Adaptor power LED flashes or shuts down .

Solution: Open the system case and use the multi-meter 200V scale to
check AD+ or DCBATOUT between GND as below . If the voltage is
less than 5V,we can make sure it is short to GND .


3.2.2 Debugging :

• There are 6 kinds of power sources in the Yuhina system, so we must check all
of the power output to see if there is any short to GND.

Solution: Check the 5V_S3,3D3V_S5,2D5V_S3,1D5V_S0,VCC_CORE and
charger power one by one .

3.2.2 Debugging : (cont’d)
Following is an example of the 2D5V power source.
1: Use multi-meter 200scale to check TC32. The impedance must bigger
than 200
. If not,it means something short to GND, and we need to find out why.
2: Usually we would remove hi & low side MOS (U65 & U69) and MAX1715.If it’s
stillshort to GND, it means some output devices are damaged, and we must try to
remove them one by one .

 

3.3.1 Symptoms:
3.3 S5 Power No Good :

• There is no any response when the power button
was pressed and adaptor has already plugged-in.
•Adaptor power LED is normal .


3.3.2 Debugging :

• Open the case, use multi-meter to check if MAX1999
pin18 5V_S5 power is good.
• If not, it means MAX1999 or some 5V_S5 devices are
damaged. Remove all powers, use multi-meter to checkMAX1999 pin18 Impedance .


• If the impedance is smaller than 200, it means some
5V_S5 devices are damaged, and we must try to
remove the component one by one.
• If the impedance is more than 200
, it means the
MAX1999 have some problem, and it must be changed.

 

3.3.2 Debugging : (cont’d)

• Next we must check 3D3V_S5. If 3D3V_DC_S5 is N.G, we could use multi
meter to check MAX1999 pin20 (19V), pin17, 28, 3 (5V) if powers are all
good. If N.G, please check the source component.


 

3.4 Power on logic N.G :
• If the previous two symptoms are checked ok, but the system still
has no power on, then we should check the power on logic circuit as
below .

1: When power button was pressed, PWRBTN# will be pulled low.
2: After a series of logic actions, the SHUTDOWN_S5 will also be
pulled low.

 

3.4.1 Symptom :

• If the power on logic circuit is correct, we can track the south
bridge trigger logic .

1: When the power button is pressed, PWRBTN# will be pulled low ,
2: After the logic action, the
PWRBTN#_ICH will also be pulled low.
It will trigger south bridge to send
PM_SLP_S4 & S3 signal to turn
3: on S3 & S0 power .


3. No Power Debug

3.4.2 Debugging :

• If SHUTDOWN_S5 is not pulled low, it means some logic ICs or
components during this path are N.G.. If it is the case, then just
follow the circuit to find out the problems, and replace them.
• If the
PWRBTN#_ICH is not pulled low, it means some logic ICs
or components during this path are N.G. If it is the case, then just
follow the circuit to find out the problems, and replace them.
• If the
PM_SLP_S4 & S3 is not pulled hi, maybe the south bridge
is damaged


To Sum up :

Above-mentioned are power system & no power debug
All of the circuit diagram are references from Yuhina .



 

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