Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Troubleshooting Laptops, Tablets, and Mobile Devices
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 06-27-2022, 01:11 PM   #1
Francisco.s
Badcaps Veteran
 
Join Date: Jan 2013
City & State: Madrid
My Country: Spain
I'm a: Knowledge Seeker
Posts: 606
Default 820-00165 pulsing

Hi, have a 820-00165 pulsing once. All voltage seems to be ok only for a moment, then it stops and takes 22 miliamps from power supply and fan stops.

cpu vcore rises to 1.8v and PLT_RESET_L goes hi level also.

SPI ROM have good pulses, but its contents are not modified, even a clean ME region remains intact. (CPU doesn't attempt to write new ME data)


SMC bypass shows the same symptoms, but fan spins faster. Charger circuit works ok and battery can be charged properly.


I have cleaned ME region and reset pram via Medusa programmer and even write a completely new bios with the same programmer.

How can I test if memory is working properly? I cant find any signal equivalent to ddr reset in the circuit diagram.
Francisco.s is offline   Reply With Quote
Old 06-27-2022, 01:17 PM   #2
mon2
Badcaps Veteran
 
mon2's Avatar
 
Join Date: Dec 2019
City & State: Windsor, Ontario
My Country: Canada
Line Voltage: 110VAC
I'm a: Knowledge Seeker
Posts: 4,119
Default Re: 820-00165 pulsing

https://www.logi.wiki/index.php/820-00165_Pulsing
mon2 is offline   Reply With Quote
Old 06-27-2022, 02:09 PM   #3
Francisco.s
Badcaps Veteran
 
Join Date: Jan 2013
City & State: Madrid
My Country: Spain
I'm a: Knowledge Seeker
Posts: 606
Default Re: 820-00165 pulsing

Quote:
Originally Posted by mon2 View Post
Hi moon2, I've read all related threads about pulsing in 820-00165 motherboard and perform some of the tests they mention.

Probably i've not tested the failed component, but I'm starting to think that a damaged cpu could be the problem.

Forgot to mention that some corrosion (sulfated capacitor) affected the +3v rtc circuit.
Francisco.s is offline   Reply With Quote
Old 06-29-2022, 03:38 PM   #4
Francisco.s
Badcaps Veteran
 
Join Date: Jan 2013
City & State: Madrid
My Country: Spain
I'm a: Knowledge Seeker
Posts: 606
Default Re: 820-00165 pulsing

After replacement of U7400 the board is working now.

PP1V2_S3 is the output of U4700, and it was ok before replacing this chip, but the waveform at pin 1 of L7430 was distorted and causes DDRREG_PGOOD not to be stable.

One of of the first thing I did, was remove Q8150 in order to disable ALL_SYS_PWRGD protection, but didn't see that this signal goes to low level via R8168 when a problem is detected in U4700 circuit.

So problem is solved.

Francisco.s is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2022
Powered by vBulletin ®
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 11:21 PM.
Did you find this forum helpful?