POST CODE Repair Guide

Lecture

POST : Power On Self Test
 The tag thrown out by BIOS
– Usually, BIOS would output some number through
80ports. Using I/O access card (debug card), user could
read those number.
– The POST codes used by Award, Phoenix, and AMI are
different.
– These numbers mean something was executing in the
system.

POST Code as BIOS executing process
 Standard POST Code
– These numbers were used as standard process.
 BIOS Debug Code
– These numbers depend on various project.

POST Code “00”,”FF” or Debug card shows all dots(……) / all 00
(1)Check Voltage:
a.) Vcore ,if no Vcore check from power block circuit diagram
b.) 1.5v,if no 1.5v check from power block circuit diagram
c.) 2.5v,if no 2.5v check from power block circuit diagram
d.) 3.3v,if no 3.3v check from power block circuit diagram
e.) check for N/B,S/B voltage is ok or not
(2)Check CLK:
a.) CPU CLK,if no CPU CLK check from CLK gen. circuit diagram
b.) N/B CLK,if no N/B CLK check from CLK gen. circuit diagram
c.) S/B CLK,if no S/B CLK check from CLK gen. circuit diagram
d.) 14.318MHz,if no 14.318MHz check from CLK gen. circuit diagram
e.) CLK generator.if all no CLK,change 14.318MHz,and then change CLK
gen. Before must check any open or short

(3)Check Power ok & Reset
a.) H/W reset,if low voltage check circuit diagram, normal is capacitor bad
b.) power supply power ok,if low voltage,normal is capacitor bad
c.) CPU power ok,if low voltage check circuit diagram,and above signal
d.) PCI reset,if low voltage check above signal and for S/B CLK,voltage
e.) CPU reset,if low voltage check above signal and for N/B CLK,voltage
f.) Check boot up sequence.
(4)Check control signal:
a.) Check CPU control signal(ADS#,BRDY#…) is ok or not
b.) Check PCI control signal(FRAME#,IRDY#,TRDY#…) is ok or not
c.) Check others control signal is ok or not

00(no data)
(1)Change BIOS
(2)Check bios voltage
(3)Check BIOS CLK
(4)Check LAD0~3
(5)Check BIOS control signal
(6)Check CPU control signal
00(Have address & data)
(1)CPU N/B:HD0~63,HA3~HA31,control signal open or short
(2)N/BS/B:PCI BUS(AD0~AD31,CBE0~CBE3) or HUB
Link(HL0~HL10) or V_link or LDT BUS open or short
(3)S/BBIOS:ISA BIOS(SA0~SA19,SD0~SD7) or LPC BUS
(LAD0~LAD3) open or short

C0 (Award)
D0 (AMI)
(1)Change BIOS
(2)Check HD0~63 signal open or short
(3)Check HA3~31 signal open or short
(4)Check AD0~31 signal open or short
(5)Check SM BUS is ok or not
(6)Check all Voltage is ok or not ,especially 2.5V,3VS
(7)Check all CLK is ok or not
(9)Check SB, especially for Intel ICH4

C1, E1, 9F, 99, Ad (Award)
D3, D4, E0, E5, A4 (AMI)
EF, EE, 28 (Phoenix)
(1)Change BIOS
(2)Check Memory voltage is ok or not, especially 3V, 2.5V, 1.8V ,
1.25Vtt , 0.9Vtt
(3)Check Memory CLK is ok or not
(4)Check SM BUS is ok or not
(5)Check MA,MD,CAS,RAS,CKE… signal is Open or Short
(6)DIMM socket not clean or bad
(7)Check HA,AD,CPU control signal is open or Short

C3 (Award)
(1)Change BIOS
(2)Check memory problem
(3)Check frequency problem
C5 (Award)
(1)Change BIOS
(2)Check memory problem
(3)Check HA3~31 is open or short
05 (Award)
(1)Check KBC CLK is ok or not
(2)Check KBC voltage is ok or not
(3)Check KBC address,data,control signal is open or short
(4)Change KBC

0B (Award)
(1)Change BIOS
(2)Check battery is ok or not
(3)Check all CLK signal(14.318MHz,25MHz,40MHz….)
(4)Check all voltage is ok or not
(5)Check INIT,TRDY#,RADY signal… is open or short
(6) Check C/BE0~3 is short or not
(7)Check all control signal(CPU,PCI,AGP) is open or short
13 (AMI)
(1) Check 1.5V to NB
20 (AMI)
(1) Check 2.5V , 1.25Vtt or 1.8V ,0.9Vtt
(2) Check Memory problems
(3) Check AGP signals

31,3D (Award)
(1)Check KBC CLK is ok or not
(2)Check K/B problem
(3)Check CPU control signal(HITM#,ITIN,ITNK#…)is
open or short
(4)Check N/B control signal… is open or short
41 (Award)
(1)Change BIOS
(2)Check SA0~SA16 is Open or short
(3)Check MEMR#,MEMW# is open or short
(4)Check HA3~31 is open or short

4E (Award)
(1)Check TRDY#,DEVSEL# is open or short
(2)Check K/B problem
61 (Award)
(1)Check Cache problem
(2)Check CPU control signal is ok or not
(3)Check N/B control signal is ok or not
85 (AMI)
(1) Check Bios
(2) Check NB (No display problem)

 AMI POST Code definition
 AWARD POST Code definition
 Phoenix POST Code definition

AMI Bios Code

POST CODE Repair Guide