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Old 06-21-2021, 10:18 AM   #1
taxxin
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Default Gigabyte ga-z77x-ud3h rev.1.0 Not turning on

I have this board here the seller told me that it doesnt power on.

Symptoms:

When the PSU is turned on and in stand by, the power button lights up, and on the POST card 3vsb is present. there is also 3v at the power switch.

When power button is pressed. everything flashes and turns on for a split second and turns back off. pressing the button more does nothing. but if you press the clear CMOS button, it powers right up again and stays on.

No post codes.

Checked the reset pin and there is 3.4v or whatever present there, which tells me that it had completed power sequence or close to completed it?

Checked the power rails for shorts everything seemed fine no shorts are present.

Checking voltages, there is 0.9v and 3.3v coming into the PCH chip. there is 1.5v for the msata, and memory, core voltage reads 0.65v, 0.36v at the bottom of the vcore.

Im quite clueless as to where to go from here? Could it be a SIO gone bad? or something in the power protection circuit dead? why would it just do a false start like that?
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File Type: jpg IMG_20210621_221203.jpg (516.8 KB, 16 views)
File Type: jpg IMG_20210621_221220.jpg (359.7 KB, 9 views)
File Type: jpg IMG_20210621_231453.jpg (525.3 KB, 13 views)
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File Type: pdf GA-Z77X-UD3H_R11.pdf (1.29 MB, 30 views)
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Old 06-23-2021, 01:54 AM   #2
dicky96
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Default Re: Gigabyte ga-z77x-ud3h rev.1.0 Not turning on

Hi Taxxin that's a remarkable coincidence as I just fixed one of the exact same model.

It had various problems, which I fixed in turn, but at one point during the repair due to a soldering error I got it doing what yours is doing (pretty much) it would turn on for a second then turn straight back off again, almost as though there was a short, but there wasn't. This was because it could not read the BIOS (or not read it correctly) and some of the odd behaviour I noticed during fault finding I think were related to the fact this board has a dual BIOS

Anyway after I got past that last problem it worked. Maybe you have some similar issues?

Here you go... enjoy
https://www.youtube.com/watch?v=4NtRxO7NIYA
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Last edited by dicky96; 06-23-2021 at 02:00 AM..
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Old 06-23-2021, 03:14 AM   #3
taxxin
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Default Re: Gigabyte ga-z77x-ud3h rev.1.0 Not turning on

Quote:
Originally Posted by dicky96 View Post
Hi Taxxin that's a remarkable coincidence as I just fixed one of the exact same model.

It had various problems, which I fixed in turn, but at one point during the repair due to a soldering error I got it doing what yours is doing (pretty much) it would turn on for a second then turn straight back off again, almost as though there was a short, but there wasn't. This was because it could not read the BIOS (or not read it correctly) and some of the odd behaviour I noticed during fault finding I think were related to the fact this board has a dual BIOS

Anyway after I got past that last problem it worked. Maybe you have some similar issues?

Here you go... enjoy
https://www.youtube.com/watch?v=4NtRxO7NIYA
Thank you Rich! Im excited to find time to watch this.
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