案例1，TCL MS81L机芯数字板
故障现象，开机电源板输出电压正常，主板上各路供电也是正常的，但是主板不输出背光开关信号，屏供电控制信号。
维修步骤：接上串口升级版，配置好SECURECRT终端工具，通电开机，发现打印信息如下：
SPI BOOT
Console Initial OK
Maria10: BD_MST004B_20AVS_10306
MIU: DDR_400Mhz_2x
BIST_0 error.
07 07
[ ]
[ ]
07 07
MIU Initial OK
分析：BIST_0 error. 是典型的DDR检测错误。但这个并不能说明就是DDR坏，因为第一个括号内部没有来自于主芯片的通讯信息，于是在检测完DDR的供电，参考电压后，大致测一遍主芯片于DDR相关的供电，发现正常之后果断更换主芯片，开机故障排除。
案例2 TCL MT01C机芯
故障现象：主板各路供电正常，但是不开机，无背光开关信号，屏供电控制信号。
检修步骤：该现象是典型的CPU工作不正常，于是开机查看打印信息。发现打印信息如下：
Boot-
DRAM Channel A Calibration.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
DRAM Input DQS Calibration fail !
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Boot-
DRAM Channel A Calibration.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
DRAM Input DQS Calibration fail !
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
Byte 0 Cal Fail.
Byte 1 Cal Fail.
相信有过相关经验的朋友都知道，Byte 0 Cal Fail.
Byte 1 Cal Fail.
DRAM Input DQS Calibration fail !
同样是典型的DDR与主芯片通讯不良，由于该主板DDR为BGA封装更换和补焊难度较大，因此重点检测DDR的供电和参考电压正常后，对主芯片进行补焊，发现故障依旧。于是测量主芯片和DDR通讯的排阻，发现一个100欧的排阻变值为1K多，更换该排阻后故障排除。
机型TCL LE32C16 机芯 MST6M48 (MSJ5) 故 障现象指示灯红灯亮不开机
维修过程：将主板上机架通电试机，发现主板上个路基本供电均正常，但指示灯呈待机红色，按按键遥控均无反应。主板无背光开关信号，以及屏供电开启信号输出。根据现象，基本能够判断出该故障系CPU工作不正常所致。连接上串口升级板，打开ISP TOOL升级工具，发现点击连接后软件能够正常识别出FLASH芯片型号，这说明基本上可以确定主芯片MST6M48的基本工作条条件问题应该不大。于是关机配置好SECCURECRT 再开机获取打印信息如下：
BOOTR2AP
INNT
55
[][]
0055 很显然DDR部分工作异常，
于是检测DDR的基本工作条件，发现供电1.8V正常，再测VREF参考电压发9现仅有0.34V，这是显然错误的，该电压应为0.9V左右。电路也很简单如下抓图：
测量R198,R202阻值无异常，A-MVREF对地阻值也无明显异常，怀疑C148漏电，拆除后发现该电压升至0.9V正常。于是以为故障排除，通电试机发现依旧红灯亮不开机。。。郁闷！于是再次获取打印信息，如下：
BOOTR2AP
INNT
55
[3456789ABCD][23456789ABC]
0087
打印至此再无信息。很显然DDR部分通讯已无异常，那么为什么CPU内程序不再跑了呢？按说至此就该运行BOOT了啊，怀疑软件有问题。于是连上升级板对主板进行软件升级，升级完成后，开机故障排除。
案例二。
机芯。TCL MT01C机芯 故障现象，机器通电主板上各路DC-DC输出电压均正常，但是不开机无背光开关信号，屏供电控制信号输出。很显然又是一例CPU工作不正常的。连接升级板，配置好SECCURECRT通电获取打印信息如下：
Boot-
DRAM Channel A Calibration.
Byte 0 : DQS(4 ~ 38), Size 35, Set 19.
Byte 1 : DQS(0 ~ 37), Size 38, Set 16.
DRAM A Size = 128 Mbytes.
Boot
Start Pmain
0x000032a0
NID=0x1d00f1ad
LZHS addr:0x00100040
LZHS size:0x00067220
LZHS checksum:0x000000ff
Boot
Start Lmain
MT5365 Boot Loader v0.9
MUSB none SoftReset 0x29424 = 0x01030000.
MUSB pBase = 0xF0029000 init ok.
MUSB none SoftReset 0x29424 = 0x01030000.
MUSB pBase = 0xF002E000 init ok.
Boot reason: A/C power on!!
Load VGA internal EDID.................
DUMMY READ EDID DATA FROM EEPROM
Load HDMI internal EDID.................
SIF_Master0: new design
SIF_Master1: old design
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
### EEPROM read loader config failed!!!
Boot reason: A/C power on!!T8032 init A/C on case loader stage...
Load T8032 FW (addr: 0x d54d60, size: 24576)success!! [Page]
LDR_FlashCopy 0xf010 0x30b80 0x80
Switch NAND pinmux
Detect NAND flash ID: 0x1D00F1AD
Detect HY27U1G8F2BTR NAND flash(SLC): 128MB
NAND_BDM_Mount: Partid=0, offset=0x0, size=0x100000
[BDM] Partition: 0, Bad Block Count: 0
Do USB upgrade
USB: Vbus turn up time = 452 ms.
No USB device.
USB upgrade stop
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
eeprom write failed, return 1
Boot reason: A/C power on!!
---------test LYQ check eeprom boot-----------
Boot reason: A/C power on!!Org:0x00 Flags:0x10
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
---------test LYQ check eeprom boot-----------
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
Disable VGA wakeup
Standby !
DRAM Channel A Calibration.
Byte 0 : DQS(4 ~ 38), Size 35, Set 19.
Byte 1 : DQS(0 ~ 38), Size 39, Set 17.
DRAM A Size = 128 Mbytes.
Boot
Start Pmain
0x000032a0
NID=0x1d00f1ad
LZHS addr:0x00100040
LZHS size:0x00067220
LZHS checksum:0x000000ff
Boot
Start Lmain
MT5365 Boot Loader v0.9
MUSB none SoftReset 0x29424 = 0x01030000.
MUSB pBase = 0xF0029000 init ok.
MUSB none SoftReset 0x29424 = 0x01030000.
MUSB pBase = 0xF002E000 init ok.
SIF_Master0: new design
SIF_Master1: old design
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
### EEPROM read loader config failed!!!
T8032 change to loader stage...
LDR_FlashCopy 0xf010 0x30b80 0x80
Switch NAND pinmux
Detect NAND flash ID: 0x1D00F1AD
Detect HY27U1G8F2BTR NAND flash(SLC): 128MB
NAND_BDM_Mount: Partid=0, offset=0x0, size=0x100000
[BDM] Partition: 0, Bad Block Count: 0
Do USB upgrade
USB: Vbus turn up time = 433 ms.
No USB device.
USB upgrade stop
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
eeprom write failed, return 1
---------test LYQ check eeprom boot-----------
Org:0x00 Flags:0x10
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
---------test LYQ check eeprom boot-----------
------[_LdrCheckEepromBoot] power mode = standby,ir or button wakeup---------
A_Mute GPIO=326 release
AMP mute GPIO=ca release
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2 [Page]
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
Reset Demod GPIO=320, 0->1
NAND load lzhs header from 0x40000 to dram(0xfe0030), size=2048
Decompression uboot to 0x00f00000...
NAND load image from 0x40000 to dram(0xfe0030), size=0x35cbb
LZHS hardware decode start
LZHS hardware decode done
Starting image...
U-Boot starts...
NAND Flash: Detect NAND flash ID: 0x1D00F1AD
Detect HY27U1G8F2BTR NAND flash: 128MB
128 MiB
Booting sequence is from NAND Flash
In: serial
Out: serial
Err: serial
SIF_Master0: new design
SIF_Master1: old design
eeprom para:140(6ffc90) u4MemLen:0x00000009
EEPROM_Read() 0
eeprom para:140(6ffc90) u4MemLen:0x00000009
EEPROM_Read() 1
eeprom para:140(6ffc90) u4MemLen:0x00000009
EEPROM_Read() 2
eeprom para:140(6ffc90) u4MemLen:0x00000009
EEPROM_Read() 3
eeprom para:140(6ffc90) u4MemLen:0x00000009
EEPROM_Read() 4
eeprom para:140(6ffc90) u4MemLen:0x00000009
EEPROM_Read() 5
eeprom para:140(6ffc90) u4MemLen:0x00000009
EEPROM_Read() 6
eeprom para:140(6ffc90) u4MemLen:0x00000009
EEPROM_Read() 7
eeprom para:140(6ffc90) u4MemLen:0x00000009
EEPROM_Read() 8
eeprom para:140(6ffc90) u4MemLen:0x00000009
EEPROM_Read() 9
EEPROM_Read() failed
Hit any key to stop autoboot: 0
Partition rootfsA defined at mtdparts:
ID:6, Offset:0x00800000, Size:0x00500000
Loading from nand0, offset 0x600000
Automatic boot of image at addr 0x00008000 ...
## Booting kernel from Legacy Image at 00008000 ...
XIP Kernel Image ... OK
OK
Starting kernel ...
Uncompressing Linux....................................................................................... done, booting the kernel.
Linux version 2.6.27 (w.y@mtkvm) (gcc version 4.4.2 (GCC for MediaTek 4.4.2-20100324)) #1 PREEMPT Sun Jan 1 06:43:14 WET 2012
CPU: ARMv6-compatible processor [410fb764] revision 4 (ARMv7), cr=00c5387d
Machine: MT5365
Memory policy: ECC disabled, Data cache writeback
CPU0: D VIPT write-back cache
CPU0: I cache: 16384 bytes, associativity 4, 32 byte lines, 128 sets
CPU0: D cache: 16384 bytes, associativity 4, 32 byte lines, 128 sets
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 15494
Kernel command line: root=/dev/mtdblock7 lpj=3506176 console=ttyMT0,115200n1 mtdparts=mt53xx-nand:1M(uboot),1M(uboot_env),1M(sigA),1M(sigB),2M(kernelA),2M(kernelB),5M(rootfsA),5M(rootfsB),28M(basic),70M(rw_area),128k(perm),128k(reserved),2M(channelsA),2M(channelsB),1M(pq),1M(aq),2M(logo)
PID hash table entries: 256 (order: 8, 1024 bytes)
Console: colour dummy device 80x30
console [ttyMT0] enabled
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
Memory: 61MB = 61MB total
Memory: 59060KB available (2492K code, 147K data, 92K init)
Calibrating delay loop (skipped) preset value.. 1402.47 BogoMIPS (lpj=3506176)
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
net_namespace: 288 bytes
NET: Registered protocol family 16
NET: Registered protocol family 2
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 2048 (order: 2, 16384 bytes)
TCP bind hash table entries: 2048 (order: 1, 8192 bytes)
TCP: Hash tables configured (established 2048 bind 2048)
TCP reno registered
NET: Registered protocol family 1
NetWinder Floating Point Emulator V0.97 (double precision)
squashfs: version 3.4 (2008/08/26) Phillip Lougher
msgmni has been set to 115
io scheduler noop registered (default)
Serial: MT5365 driver $Revision: #2 $
ttyMT0 at MMIO 0xf000c000 (irq = 17) is a MT5365 Serial
ttyMT1 at MMIO 0xf000c000 (irq = 17) is a MT5365 Serial
ttyMT2 at MMIO 0xf0028800 (irq = 0) is a MT5365 Serial
ttyMT3 at MMIO 0xf000c000 (irq = 17) is a MT5365 Serial
brd: module loaded
compcache: compcache size not provided. Using default: (25% of Total RAM). [Page]
Use compcache_size_kbytes module param to specify custom size
compcache: Compressed swap size set to: 14780 KB
TLSF: pool: c4009000, init_size=16384, max_size=0, grow_size=16384
PPP generic driver version 2.4.2
PPP Deflate Compression module registered
PPP BSD Compression module registered
NET: Registered protocol family 24
Detect NAND flash ID: 0x1D00F1AD
Detect HY27U1G8F2BTR NAND flash: 128MB
NAND device: Manufacturer ID: 0xad, Chip ID: 0xf1 (Hynix NAND 128MiB 3,3V 8-bit)
17 cmdlinepart partitions found on MTD device mt53xx-nand
Creating 17 MTD partitions on "mt53xx-nand":
0x00000000-0x00100000 : "uboot"
0x00100000-0x00200000 : "uboot_env"
0x00200000-0x00300000 : "sigA"
0x00300000-0x00400000 : "sigB"
0x00400000-0x00600000 : "kernelA"
0x00600000-0x00800000 : "kernelB"
0x00800000-0x00d00000 : "rootfsA"
Squshfs - mtdblock6: block 26 is bad!
0x00d00000-0x01200000 : "rootfsB"
0x01200000-0x02e00000 : "basic"
0x02e00000-0x07400000 : "rw_area"
0x07400000-0x07420000 : "perm"
0x07420000-0x07440000 : "reserved"
0x07440000-0x07640000 : "channelsA"
0x07640000-0x07840000 : "channelsB"
0x07840000-0x07940000 : "pq"
0x07940000-0x07a40000 : "aq"
0x07a40000-0x07c40000 : "logo"
TCP cubic registered
NET: Registered protocol family 17
VFS: Mounted root (squashfs filesystem) readonly.
Freeing init memory: 92K
INIT: version 2.86 booting
Mounting local filesystems: mount mount: according to /proc/mounts, /dev/root is already mounted on /
Loading /etc/profile...
Running rc.local...
net.ipv4.tcp_window_scaling = 6
# mount basic
UBI device number 0, total 224 LEBs (28442624 bytes, 27.1 MiB), available 0 LEBs (0 bytes), LEB size 126976 bytes (124.0 KiB)
real 0m 0.09s
user 0m 0.00s
sys 0m 0.05s
UBIFS: recovery needed
UBIFS: recovery completed
real 0m 0.05s
user 0m 0.00s
sys 0m 0.03s
SIF_Master0: new design
SIF_Master1: old design
EEPROM_Read() 0
DTV>EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
[_read_project_id_from_eep] 1:32 fail!!
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
[_read_project_id_from_eep] 1:62 fail!!
EEPROM_Read() 0
EEPROM_Read() 1
EEPROM_Read() 2
EEPROM_Read() 3
EEPROM_Read() 4
EEPROM_Read() 5
EEPROM_Read() 6
EEPROM_Read() 7
EEPROM_Read() 8
EEPROM_Read() 9
EEPROM_Read() failed
[_read_project_id_from_eep] 2:172 fail!!
[_read_project_id_from_eep] eeror Three project id not all same
prj_id_array[0] = 32,prj_id_array[1] = 62,prj_id_array[2] = 172
EEPROM_Write() 0
EEPROM_Write() 1
EEPROM_Write() 2
EEPROM_Write() 3
EEPROM_Write() 4
EEPROM_Write() 5
EEPROM_Write() 6
EEPROM_Write() 7
EEPROM_Write() 8
EEPROM_Write() 9
EEPROM_Write() failed
[_write_project_id_to_eep] 1:0 fail!!
EEPROM_Write() 0
EEPROM_Write() 1
EEPROM_Write() 2
EEPROM_Write() 3
EEPROM_Write() 4
EEPROM_Write() 5
EEPROM_Write() 6
EEPROM_Write() 7
EEPROM_Write() 8
EEPROM_Write() 9
EEPROM_Write() failed
[_write_project_id_to_eep] 2:0 fail!!
EEPROM_Write() 0
EEPROM_Write() 1
EEPROM_Write() 2
EEPROM_Write() 3
EEPROM_Write() 4
EEPROM_Write() 5
EEPROM_Write() 6
EEPROM_Write() 7
EEPROM_Write() 8
EEPROM_Write() 9
EEPROM_Write() failed
[_write_project_id_to_eep] 3:0 fail!!
[PrjAttributeInit] Read project id fail!!
EEPROM_Write() 0
EEPROM_Write() 1
EEPROM_Write() 2
EEPROM_Write() 3
EEPROM_Write() 4
EEPROM_Write() 5
EEPROM_Write() 6
EEPROM_Write() 7
EEPROM_Write() 8
EEPROM_Write() 9
EEPROM_Write() failed
[_write_project_id_to_eep] 1:0 fail!!
EEPROM_Write() 0
EEPROM_Write() 1
EEPROM_Write() 2
EEPROM_Write() 3
EEPROM_Write() 4
EEPROM_Write() 5
EEPROM_Write() 6
由上述打印信息可以看出DDR ,BOOT,NAND 都基本上检测正常，唯独从
EEPROM_Read() failed
### EEPROM read loader config failed!!!等处可以看出CPU对存储器的读写异常。于是测量存储器总线电压，发现SCL线仅1.2V，SDA线基本正常。对地测试SCL脚对地阻值，发现明显偏度，断开该总线上所连的CPU,以及高频头该阻值依旧很低，怀疑过孔漏电，于是割断过孔铜箔直接飞线连接。开机后SCL电压升至3.3V，开机一切正常。
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