迅维网
标题: LA-G131P VCC_GT rail problem | short circuit SoC CPU i7-8th H & DrMOS [打印本页]
作者: vusalcrm 时间: 2023-5-13 03:10
标题: LA-G131P VCC_GT rail problem | short circuit SoC CPU i7-8th H & DrMOS
There is a customer complaint: but there is no image. Thecustomer himself did the cleaning and maintenance of the motherboard. then hecollected the computer and there was no vision
Visually inspected the motherboard once. I didn't see anybroken resistance or a damaged line.
Took the motherboard out of the case. There was anisolated label on the back of the motherboard.
Took it off. and I saw that anSMD capacitor belonging to the CPU VCC_GT line had fried. and it was shortcircuited.
Removed the short circuit capacitor. I started the motherboardstill the same situation. fans freeze fast and no display.
Said to myselfthat I need to examine it from the sky now. there was signal timing in theschematic of the motherboard.
Measured everything in order with the method. Iknow and the timing on the motherboard.
All VRM output on the motherboard wasintact. there was just no VCC_GT voltage.
There was an abnormally low value on the CPU VCC_GT line. 0.002 ohms.this was so abnormal.
Removed the DrMOS IC. there was still a short on theVCC_GT line
There was a high probability that the CPU was bad. Ordereda scrap motherboard on ebay.
Motherboard belongs to dell machine. had liquidcontact. Measured the CPU line, there was no short circuit. I changed the CPUat risk.
Took remeasures and the CPU line VCC_GT was normal. the averagevalue is 0.023 ohms
Everything is perfectly normal. I changed the CPU. Iconnected it to the power source and started.
Still no image and still no voltage VCC_GT
Let's think a little...
Why is there still no image? The current drawn from thepower supply is normal.
Meanwhile I reprogrammed the BIOS and EC. I edited theBIOS on the official site. I'm pretty sure it's the BIOS.
I connected post card from EC Debug line. post code 63. this error code points to IntelHD graphics card
The VCC_GT voltage should rise instantaneously at the firststart time.
I need an oscilloscope to see this too. When I examine it with anoscilloscope, there is no reaction at the VCC_GT voltage.
DrMOS measurements
VCC - 5V active
VIN - 19V active
DRON - 4.94V active
PWM – 5V – this is not normal. When I look with an oscilloscope, this signal is a flat DC voltage.
But normally at low voltage and Ishould see a PWM signal
I then measured the BOOT resistance. I saw that theresistance value is abnormal. normally 4.7ohm. But when I measure 1.2kohm.
BOOT (5pin) and PHASE (7pin) were shorted. I thought thecondenser is broken.
The olctum condenser is out. It was not a short circuit.Then I removed the DrMOS IC.
I've measured out and still pins 5-7 are shorted.This means that DrMOS is now corrupted.
For this reason, the main VRM wassending a straight DC signal as it detected a short circuit.
Now I found the culprit
NCP302045 is written on the schematic of the motherboard.
But on the motherboard part code AEQ0 - AOZ5312UQI
Since I don't have this integrated in my hand, I replaced itwith Sic632 ( 55A )
All problems with motherboard are now solved
Good day...
作者: fixlover 时间: 2023-5-13 10:07
标题搞错了吧。图片里是 la-f541p，不是 LA-G131P 哦。
(it is not a LA-G131P. la-f541p in the picture.)
作者: 恋上【妳的床】 时间: 2023-5-13 14:33
全英文，看不懂
作者: 873808892 时间: 2023-5-13 17:15
It should be that the pipe burned through and burned out the CPU
作者: vusalcrm 时间: 2023-5-14 00:19
I'm aware of that my friend
dell motherboard i bought from ebay for second hand CPU
作者: vusalcrm 时间: 2023-5-14 00:23
google translate
作者: 乘吉思翰 时间: 2023-5-14 07:46
Nice work!
作者: 乘吉思翰 时间: 2023-5-14 07:47
Nice work！！
作者: xfzl 时间: 2023-5-14 18:13
不说句英语都不好意思回复，你这个很OK啊
作者: 小李001 时间: 2023-5-14 19:08
路过学一下，太难了
作者: u1478269 时间: 2023-5-14 19:42
路过围观，全英文把我都看懵了
作者: u1499872 时间: 2023-5-14 20:22
太高科举看不明白
作者: gingerluo 时间: 2023-5-14 23:31
支持老铁，老想去外高加三国玩一玩了，老铁接待不
作者: u1473357 时间: 2023-5-15 00:06
路过，学习了
作者: sainie2013 时间: 2023-5-15 08:55
全英文，还好，能看懂了一点点意思！
| 欢迎光临 迅维网 (https://www.chinafix.com/) |
Powered by Discuz! X3.4 |
