HOW TO CHECK 3V, 5V (RT8206b) SYSTEM ON LAPTOP MOTHERBOARD

Laptop Motherboard need 3V and 5V power system. This 3V_ALW supply VSB (voltage switch
button)-EC Bios IC-EC (embedded controller)-SB (South bridge) and more other important
component. 5V supply power Source for any switching transistor and device. (USB-HDD-Optical etc).

Without this 3V and 5V Power circuit board will totally death.RT8206A/B dual step-down, switch-
mode power supply (SMPS)controller generates logic-supply voltages in battery-powered systems.
The RT8206A/B includes two pulse-width modulation (PWM) controllers fixed at 5V/3.3V or
adjustable from 2V to 5.5V. An optional external charge pump can be monitored through SECFB
(RT8206A).This device also features a linear regulator providing a fixed 5V output.

Checking this IC need to know how they work and knowing important input and output Voltage .

Checking the problem by the Symtom:

Service log is made by technicians to make a record of faulty motherboard electricity and signal
system , every single voltage and signal measurement are notice in this log.To narrow the search of
missing voltage and signal.

1.Dead motherboard:

no led indicator at all, no fan moving ,no power .This mother board require an adapter voltage
(12V_15V_16V_18.5V_19V_20V) also 3V and 5V to completely VALW power supply need. without
this impossible motherboard to a life.

Starting with checking power jack to ensure adapter continuity supply P channel mosfet transistor
ended to P channel mosfet transistor for battery fet.This line power contribution called Main circuit
line of VALW power supply.Open schematic (ensure match motherboard and schematic code)for
charger IC page and trace started from DC jack to adp P channel mosfet (or same motherboard using
Inductor or Diodes to replace transistor on circuit) make sure continuity supply for charger IC
VCC,DC/DC main supply IC VCC and each Upper N channel SOURCE to produced 3V and 5VALW.Signal
confirmation EC Bios working name is RSMRST# for 3.3V

2.No display motherboard:

led indicator on, switch on but no internal or external display.There are 3 boot strap device
supported to make motherboard load to display of course after Bios system working properly :

A.Processor:

Without this motherboard will not be able to display. power name by VCCORE and enable signal
called VR_ON or V_RON as a trigger from Embedded controler(EC) to enable or disable VCCORE IC.
Processor need power supply greater than 1.05V but some AMD processor only need power greater
than 0.9V.

B.SODIM:

Sodim power called VCCRAM.There are 2 VCCRAM need to make sodim working :1.5V and 0.9VTT for
DDRIII and 1.8V_0,75VTT for DDRII.

C.CHIP's(SB/NB/VGA):

Chip Power called VCCP. There are very complex power supply system. Chip need 19VALW-5/3VALW-
5/3VS-1.2VS-1.05VS.Chip also have they own RAM and need power supply to working. Signal
confirmation chip was ok on chip PWRGOOD for 3.3V or tolerance 10%

Note every missing power and replace damage component.

3.Power Drop:
Led Indicator on ,switching on, on for few second after that back off. This symptom happen because
power spike or there is shortage on VS line. Processor and Chip are most which can cause power
spike, look at VCORE and VCCP circuit line ,circuit has provide stockpile empty pad to add some more
capacitor to anticipate power spike during boot up process. The other problem of power drop are
some shorted on VS line ,so after switch on VS active 1 or more VS line got a feed back caused power
down and shutdown the system.

4.VALW SHORTED:

Adapter led Blinking or drop, Current high Voltage down, no movement at all(Dead shorted
motherboard).This feed back comes from VALW main power supply line. Checking this by traceing
any sorted component on VIN and VBAT+line. Finding shorted by checking all component having
Cathode and anode.

5.No switch/Can not Switch on:

There are few system switch found for different circuit manufacture, measuring switch voltage on
one of switch button pin, before switch standby power available for 17~19V comes from 51_ON#and
after switch on power switching vcc 3.3V replace 51_ON# supply than EC_ON# one of pin Embedded
controller reacted for on/off mode.

Switching system shorted power switch to the ground, while shorted vcc become zero volt than
3.3V_vcc replace 51_ON# 17-19V become 3.3V.this signal read by Embedded controller to switch on
or switch off the system. The other system used 3 or 5V switch button VCC. when 3or5V shorted to
the ground by switching button ,3V will drop to zero volt(for 1 second) EC will reacted to power on
the system and when 3or5V shorted for more than 3 second ,EC will reacted to power off the system.

HOW TO CHECK NO DISPLAY PROBLEM ON CIRCUIT PROCEDURE

1a.Check device : processor , memory / SODIM , webcam , modem , wifi , card reader etc.

1b.processor/SODIM tested , SWITCH on again .

1c. physical analysis components : memory sockets loose , component crashes , burns , cracked ,
broken or any form of physical damage .(Make a replacement if any)
1d.check procesor vccore voltage ( schema apply ) INDUCTACE ( R36 , R45 , R56 ) / capacitor ( 330uf
- 220uF - Tokin NEC super capacitor ) range 1.0VS~1.5VS to normal operate.

example ic / chip For cpu power is : ( VCCORE / CORE CPU / CPU DC / POWER processors )

Example Vccore IC/VRM controller :

(ADP3166 ADP3170 ADP3421 AIC1567 CS5322 FAN5056 ITC1709 MAX1710/MAX1711/MAXl712

HIP6004 , ADP3212'MAX8760 , MAX8770 , MAX8771 , ISL6260 , ISL6265A , ISL6266A , ISL62882 ,
ISL6262A,ISL6218CV - T , ISL6269CCR .. etc )

1e : check for memory and power voltage conductors and ground socket interface memory. VCCRAM
normal operational voltage 1.8 V and 0.9VTT for (DDRII) and 1.5V/0,9VTT for (DDR3)

examples of memory / power SODIM ( schema languages : VDDR / POWER MEMORY / VTERM / DDR
PWR ) ic examples : (MAX8794 NCP5201 SC1486/SCl486A SC2616 TPS51020 ISL6520 ISL6537 CM8501
, ISL6224 ISL6225 , TPS51116EGR , RT8207A ... etc ) .

1f.cek voltage on S.I.O /EMBEDDED CONTROLLER chip:

S.I.O managed a lot of signal, start from pwr button signal, switching VALW to VS power and steeping
process signal sleep state. We can detected normal ic and firmware bios from confirmation signal of
RSMRST#3.3V .If SPI setting, IC bios and firmware not working, this S.I.O will not working. This S.I.O
programme by microcontroler .(download example S.I.O datasheet to get more information)

S.I.O chip samples are :

(WINBON/ENE/ITC/NOUVOTON/ PC97338 , PC87392 , FDC7N869 , FDC37N958 , LPC47N227 ,

LPC47N267 PC87591S / PC 87591L / PC 97317IBW/PC 87 393 VGJ PC87591E , WPC8768L , KB926D
etc ) .

1.g.check voltage and ground at the thermal sensor IC

Thermal sensors ( heat sensor ) is a sensor chip that detects heat safe limits to maintain security
motherboard chips. almost all laptops have a thermal sensor to microprocessor and some
motherboards have a thermal Graphic chip to chip .Thermal sensor will give orders to the bios if it
detects a maximum heat limit to disconnect power to the processor or VGA or just turn off
bootstrapping ( command to boot ) and stop the interface between components that aims to keep
the excessive heat damage the chip ( protect error ) .
Detect due to frequent excessive heat can cause thermal sensor or faulty memory detection and
sensor commands do not get along (False alarm). Thus the chip detects heat temperature maximum
continuous conditions, although they are not.

To reconcile the sensor detection is by lifting the chip from the motherboard and put back to give the
induction . if the sensor is already damaged and could not be reset we will have to replace the sensor
chip that is still accurate .

ic examples :

ADMI032 , EMC1402 , EMC4402 , EMC4401 , GMT781 , G768B , MAX6642 , MAX6657 , SMC1423 ..

etc

1.h.cek voltage or frequency of the clock generator:

sample clock generator chip :

ALPRS355B MLF64PIN, CK505, CK408, K410M, CY2854LVX , ICS9LPRS387 , ICS9LPR600

ICS951412 , ICS954213 , ICS9LPR363DGLF - T , ICS950810 , SLG8SP626 , SLG8SP513V ,

SLG8LP465VTR,SLG8SP553V , SLG8LP55VTR , SLG8SP513VTR ... etc.

2.a.Check Chip power

2.b.Check chip signal and state trigger.

2.c.Check Bios microcontroller system(including check for S.I.O or embedded controler)

2.d.SB/NB/Chip analyses .

2.e Reflow~reball~replace the chip . ( Fixing ball lead / tin loose chip due to heat )

note : Chip -level is not described in detail on the basis of the material .

sample chips :

SB/NB/ CHIP : - ( PC97338, PC87392, FDC7N869, FDC37N958, LPC47N227, LPC47N267 PC87591S / PC

87591L / PC 97317IBW/PC 87 393 VGJ PC87591E etc ).

- Graphics Brand : -

( ATI , NVIDIA , S3 , NEOMAGIC , TRIDENT , SMI , INTEL , FW82807 , and CH7001A , etc. .

GPUCORE / GFXCORE / VCVOD / GRAPHIC POWER

MAX8792ETD + T , MAX8792ETD , ISL6263 .. etc

There are few system switch found for different circuit manufacture. measuring switch voltage on
one of switch button pin, before switch standby power available for 17~19V comes from 51_ON#and
after switch on power switching (VSB) 3.3V replace 51_ON# supply than EC_ON# one of pin
Embedded controller reacted for on/off mode. Switching system shorted power switch to the
ground, while shorted VSB (Voltage Switch Button) become zero volt.

FIRST RESET SIGNAL ON COMPUTER CIRCUIT

RSMRST#

When the Power, Bios,Ec are OK, the RSMRST# will go high. In the other word, this pin go Low only
when the system reset.If BIOSdata is error, RSMRST# won’t go high.

Here PCH(platform controller host) is the combination of north and south bridge.

Laptop Troubleshooting – Symptoms of PCH CPU and SIO Failure!

For any computer to work properly, there are several circuits and microchips that must cooperate on
the motherboard. These include the all-important processing unit (CPU), the Platform Controller Hub
(PCH) and the Serial Input/Output (SIO). All these units have individual functions that collaborate to
make one interconnected system.

How the CPU, PCH, and SIO Work Together in a Laptop Motherboard

The PCH (Platform Controller Hub) can be referred to as a family or set of Intel Microchips. As the
name suggests, the PCH controls various data paths and functions that work with the Central
Processing Unit.

The SIO, on the other hand, is an integrated circuit located on a computer’s motherboard that
handles the slower, less demanding input/output devices. In conjunction with the CPU and the PCH,
the Serial Input/Output has control over floppy disk controller, infrared, parallel ports, serial
ports(DB9) and mouse as well as temperature and fan speed in your computer.

Symptoms of Damaged or Failing PCH, CPU, and SIO

–Computer turns on without any display or sound.

-Computer fans run at much higher speeds even when computer is idle

-Operating system freezes unexpectedly

-temperature rises unusually/suddenlly

-All serial and parallel ports do not work

-Frequent, unexpected system shut down