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Old 11-25-2020, 09:56 AM   #1
madan1
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Default Asrock Z87 Extreme 4 schematics

Hi everyone, are there any schematics for that motherboard? A friend dropped me one that has intermittent issues - some times ( usually a very cold start ) it is able to load the whole POST, but after that it even fails to start any post codes.
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Old 11-25-2020, 11:15 AM   #2
piernov
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Default Re: Asrock Z87 Extreme 4 schematics

No schematics available only boardview.
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Old 11-25-2020, 12:46 PM   #3
madan1
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Default Re: Asrock Z87 Extreme 4 schematics

Yes, I just got familiarized with boardview.
So any ideas from where to start?
The most common state of the board is just to stay in a power-boot loop ( the PSU keeps turning on/off ) without any indication on the board ( no power on LED, no status code ).
Still, from time to time it manages to start booting ( LED on, some status codes ).
I'm testing the MB with a CPU, but without RAM.
Oh, and one more thing - vcore to gnd ~15ohms with CPU and ~80-90ohms without CPU.. is this normal? All other rails ( capacitors ) have at least few kOhms to gnd.. only the vcore is that low.
Also, when hooked up to a PSU, while trying to power on, only the USB hub controller heats up ( not like getting hot, but like warm.. indeed around 30-35C* ).. everything else stays with room T.

P.S. When my colleague received the MB, he was able to power it on and get into the bios and do some changes. Saved the changes and after that it started failing. The MB has two bios chips and the colleague already tried reflashing one(?) of them with a programmer and factory bios.

Last edited by madan1; 11-25-2020 at 12:57 PM..
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Old 11-25-2020, 05:58 PM   #4
madan1
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Default Re: Asrock Z87 Extreme 4 schematics

Since this is my first MB repair attempt on this level, any input will be appreciated

So, just some more testing.. and deducting.
When the MB does not want to start, it just cycles the PSU... just like a SMPS is trying to start. If it was a short on the rails that come from the PSU, then I would expect the PSU to enter in protect mode and require a hard reset ( it's a good quality PSU ).. so I guess the main power rails are at least not shorted.

One very important thing - when the MB is trying(?) to start, the LEDs/backlight on the power btn, reset btn and code display do not power up.
I traced the LED power to pin116 LED_EN on u1007 controller ( NCT6776D(FAC) LQFP128 NUVOTON LPC I/O ). +5vsb is present on q13 pin2. Pin1 also has +5v when bad. 3.3V is present on the passives near the IC ( 3.3v cycles with the rest of the PSU rails ).
But I also got powered LEDs by turning off and then on the PSU, while the capacitors on the MB were still not fully discharged ( like the MB started fine, then turned off the psu... the leds stayed on for a second or so, turned on the psu and pressed the ON button on the MB ... the leds stayed on, but the MB again failed to turn on.. no codes on the mb display ).

I'm starting to think that the MB is not even reading the bios.. which seems to be done by the southbridge. Am I correct to think that the southbridge is commanding u1007?
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Old 11-28-2020, 05:07 PM   #5
SMDFlea
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Default Re: Asrock Z87 Extreme 4 schematics

similar thread here: https://www.badcaps.net/forum/showthread.php?t=79449
And dicky96,the "dude from badcaps" had further progress on the eevblog forum - https://www.eevblog.com/forum/repair...e-after-sleep/

Last edited by SMDFlea; 11-28-2020 at 05:08 PM..
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Old 11-29-2020, 02:37 PM   #6
piernov
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Default Re: Asrock Z87 Extreme 4 schematics

I thought this was only a schematics/boardview request. I moved back to the main forum.

Low resistance to ground on CPU VCore with CPU inserted is normal. Without CPU, it should start charging capacitors and climb to several hundred ohms or several kohms.

U1007 is the SIO, and it deals with part of the power sequence among other things. The PCH also deals with part of the power sequence. They go back and forth to transition between power states. However if you get to an S0 state the power sequence should be mostly good. You can at least check your power rails such as CPU VCore, RAM VDDQ/VTT, PCH 1.05V rail for example.
This doesn't exclude the SIO or the PCH being partially dead.


As a side note I had a similar board (B85 Pro4) where the regulator for the 1.05V rail was bad and was sending 2V, that killed the PCH, it was power cycling as soon as it tried to access the SPI ROM (without SPI ROM it wasn't cycling but of course no POST). On another board (MSI H81M-E34) the PCH was shorted on its 3V S0 rail, somehow it was still getting into an S0 state but nothing more. Both were fixed after replacing PCH (and 1.05V regulator for the first one).
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Old 12-02-2020, 04:54 PM   #7
madan1
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Default Re: Asrock Z87 Extreme 4 schematics

Thank you for the links!
I read the eevblog topic and decided to give up.. too complicated for first MB repair.. but then gave it one last chance by measuring the 1.05V rail and voila - it fails to start. IC PU9 has a good 5V power supply, also gets 5V on the EN pin, but on the output there is only 0.10-0.15V for very short time. Injected ~1v from a bench PSU and after a couple of power on/off cycles, eventually the MB boots.. and this happens every time I switch on the external psu.
So now I wonder whether to order a new RT8065 and hope for the best ( the worst thing is that the MB still boots from time to time... so something went "partially bad" and I'm not sure if it is the IC, a passive from it's circuit, a trace or whatever... ) or just install an external regulator and bypass the PU9...
What would you do?

Last edited by madan1; 12-02-2020 at 05:02 PM..
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Old 12-02-2020, 05:30 PM   #8
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Default Re: Asrock Z87 Extreme 4 schematics

Yes you can try to replace PU9, If it gets 5V on pin 4 and pin 3 is high, and nothing around it looks out of the ordinary but it doesn't work as expected, you can definitely suspect it.
Incidentally it was the one that failed on the my B85 Pro4 case, but of course not all failures are the same.
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Old 12-03-2020, 02:37 PM   #9
madan1
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Default Re: Asrock Z87 Extreme 4 schematics

So most likely next week the voltage regulator will arrive and will replace it.
By the way, there is a very strange behavior - if I stop the auxiliary 1V supply after the POST has passed, the MB continues to work just fine. The 1V rail is also present.
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Old 12-17-2020, 06:57 AM   #10
madan1
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Default Re: Asrock Z87 Extreme 4 schematics

The chip is changed and now the MB seems to be working fine.
Thank you.
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Old 12-21-2020, 10:54 AM   #11
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Default Re: Asrock Z87 Extreme 4 schematics

@madan1
Well done
My Extreme 4 still isn't working though I haven't spent much time on repair work the last few months due to concentrating on some new business ventures

On mine, the Vcore continually tries to power on then powers off again. What I can say for sure is that phase 1 is behaving different from all the other phases (2-6 seem to behave identically)

The main difference on mine is that phase 1 sends pulses from the controller for longer (a lot more pulses) in each power on attempt, than on the other phases.

I thought it was a faulty MosFET or MosFET driver on Phase 1 Vcore and I ordered some spares but I didn't change them yet because now I am not so sure.

The Vcore controller is an ISL6379 and this is behaving differently on PWM1 output than the other PWM outputs. I can't find a pinout for the ISL6379 but the pins are names on the Boardview so it gave me some idea what I should check. So fa I can't see any Enable Pin or similar that is shutting the ISL6379 back down each time it starts and I have a look at the Sense+ and Sense- pins for each phase and can't see any obvious difference either so I don't think it is an Over current condition on any of the phases that shuts it down

Probably I should order some ISL6379 and see if changing it fixes anything.


It would also be good to be able to inject 1V or there-abouts Vcore from an external PSU to see if the Motherboard will then start, but my 0-30V 5A PSU isn't gonna do it and googling for a 'Vcore Bench test PSU' didn't find anything interesting

I suspect there is someway to do this, even maybe by 'commandeering' the Vcore supply from a scrap motherboard or maybe better using the 1V supply from a scrap Graphics card like a GTX780 or something?

Last edited by dicky96; 12-21-2020 at 10:56 AM..
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Old 01-07-2021, 09:20 PM   #12
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Default Re: Asrock Z87 Extreme 4 schematics

good
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