User Profile

jackster replied to 800W PC PSU by Corsair with fluctuating 5V

in Troubleshooting Power Supplies and Power Supply Design

02-21-2024, 03:52 AM
Thank you for the suggestion, I think it looks like 3.3V and 5V are on the same transformer. And the 5V output rectifier seems to be this one (STPS3045CW, circled with red colour):
[URL=filedata/fetch?id=3220517&d=1708508688][ATTACH=JSON]{"alt":"Click image for larger version Name:\t20240220_212935.jpg Views:\t0 Size:\t2.76 MB ID:\t3220517","data-align":"none","data-attachmentid":"3220517","data-size":"medium"}[/ATTACH][/URL]

Might as well order some of those rectifiers just in case, the voltage...

See more | Go to post
Leave a comment:
jackster replied to 800W PC PSU by Corsair with fluctuating 5V

in Troubleshooting Power Supplies and Power Supply Design

02-20-2024, 02:15 PM
I replaced the two 16V 2200uF electrolytic caps in the 5V rail today but it didn't help so the problem is elsewhere.

So I followed your suggestion and went searching for the voltage comparator of +5V and I think I found it, it's a Texas Instruments TL431AC. It seems to be connected to the +5V rail via these two resistors:

[ATTACH=JSON]{"data-align":"none","data-size":"medium","data-attachmentid":3220201}[/ATTACH]

Now I just need to wait another month for the replacement comparators to arrive from aliexpress...

See more | Go to post
Leave a comment:
jackster replied to 800W PC PSU by Corsair with fluctuating 5V

in Troubleshooting Power Supplies and Power Supply Design

01-25-2024, 07:12 AM
No there are not separate regulation modules AFAIK but there are separate chokes for each rail (3 in total). And oh yes sorry the exact model is Corsair Gaming Series GS800, techpowerup has good pictures of it: [URL]https://www.techpowerup.com/review/corsair-gs800/4.html[/URL]https://No there are not separate re...0/4.html[/URL]...

See more | Go to post
Leave a comment:
jackster replied to 800W PC PSU by Corsair with fluctuating 5V

in Troubleshooting Power Supplies and Power Supply Design

01-25-2024, 04:45 AM
Each rail is independently regulated. The two 16V 2200uF electrolytic caps in the 5V rail look good on the top, but it's very hard/almost impossible to see the rest of them due to so many cables and other components cramped right next to them.

But just in case I have already ordered replacement caps....

See more | Go to post
Leave a comment:
jackster started a topic 800W PC PSU by Corsair with fluctuating 5V

in Troubleshooting Power Supplies and Power Supply Design

01-24-2024, 07:08 AM
800W PC PSU by Corsair with fluctuating 5V

So I have an old 800W ATX PSU which works otherwise but the 5V rail fluctuates between 4.5V and 5.1V [B]even with no load. [/B]Under load the fluctuation seems to be the same, at least with one mechanical hard drive connected.

3.3V and 12V are fine.

All electrolytic caps look ok visually, but should one still start the repair/diagnosis by replacing all relevant caps?So I have an old 800W ATX PSU which works otherwise but the 5V rail fluctuates between 4.5V and 5.1V [B]even with no load. [/B]Under load the fluctuation seems to be the same, at least with one mechanical

See more | Go to post
jackster replied to Asus Z270-K schematic

in BIOS & Schematic Requests!

02-19-2023, 02:04 PM
Re: Asus Z270-K schematic

Thank you!...

See more | Go to post
Leave a comment:
jackster started a topic Samsung Curved monitor C27FG70FQU with garbled vertical lines on startup

in Troubleshooting Computer Displays

02-13-2023, 01:56 PM
Samsung Curved monitor C27FG70FQU with garbled vertical lines on startup

I acquired a faulty curved Samsung C27FG70FQU which has the quite common problem of just showing weird vertical lines for a while after a cold boot.

The issue is pretty bad with this one and it takes about 15 minutes before things normalize and a proper image is displayed. Once a proper image is shown it will work 100% until the display is shut down or put in standby for a while and allowed to cool for a bit.

Even though this seems to be a quite common issue I haven't really found any information regarding what the root cause is and how to fix it. There is this video...

See more | Go to post

Last edited by jackster; 02-13-2023, 02:02 PM.
jackster started a topic Asus Z270-K schematic

in BIOS & Schematic Requests!

02-10-2023, 03:42 PM
Asus Z270-K schematic

Got an electrically broken USB port and I'd like to find out what it connects to. I have the Asus Z270-P schematic but unfortunately it differs quite a lot from my board with regards to the USB port in question...

Thanks!

See more | Go to post
jackster replied to Strix GTX 970 powers up, but PC does not POST + no video

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

12-01-2021, 01:47 PM
Re: Strix GTX 970 powers up, but PC does not POST + no video

In case the card does not work due to the 3 missing 0201 decoupling capacitors, what kind of capacitance values do you think they could have? I might try replacing the missing caps with new ones but I don't know what capacitance they should be...

See more | Go to post
Leave a comment:
jackster replied to Strix GTX 970 powers up, but PC does not POST + no video

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

12-01-2021, 01:10 PM
Re: Strix GTX 970 powers up, but PC does not POST + no video

So I managed to obtain the board schematics and I went through all of the components on the board, and didn't find any missing components *except* for three of the tiny components right next to the GPU die itself. The previous owner must have scrubbed too hard when removing old thermal paste or something. Could those three missing components (probably capacitors??) next to the die cause the card to not be detected properly and abort the POST process?

See more | Go to post

Last edited by jackster; 12-01-2021, 01:27 PM.
Leave a comment:
jackster started a topic Strix GTX 970 powers up, but PC does not POST + no video

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

11-29-2021, 11:28 AM
Strix GTX 970 powers up, but PC does not POST + no video

Alright so I got a faulty Strix 970 which prevents the PC from POSTing when plugged in and there is obviously no picture either. The fans on the card spin up on boot and the indicator LED on the rear lights up, but the computer won't POST and the keyboard is non-responsive. There is no video out on HDMI, Displayport or DVI.

There are no shorts on the +12V inputs. I have measured 1.0V on all core VRM inductors and 1.1V to the memory chips. 3.3V and 5V are also present so everything seems to check up voltage-wise however I am not certain if I have measured everything that I should (I'm...

See more | Go to post
jackster replied to New Members - please post your introductions here

in Announcements & Related News

11-29-2021, 03:58 AM
Re: New Members - please post your introductions here

Hi everyone. Trying to get into GPU repair, and this seems like just the right place for information regarding that topic!

See more | Go to post
Leave a comment:

No activity results to display

Announcement

Profile Sidebar

Leave a comment:

Leave a comment:

Leave a comment:

Leave a comment:

800W PC PSU by Corsair with fluctuating 5V

Leave a comment:

Samsung Curved monitor C27FG70FQU with garbled vertical lines on startup

Asus Z270-K schematic

Leave a comment:

Leave a comment:

Strix GTX 970 powers up, but PC does not POST + no video

Leave a comment: