ASRock H81 only powers on with 24 pin jumped

[timma100]

I've got an ASRock H81 board that wont power on at all with the front panel power pins.. The only way to get the board to start is to jump pins 3&4 on the back of the board. The board stays on until I remove the jumper, but no display or post. So some basic logic on the board isn't functioning. I'd like to get it to work, I've got plenty of spare LGA 1150 CPUs/RAM to test.. My first thought is the bios chip is completely toasted, but looking for any suggestions or tips to identify possible causes before I go and buy a bios chip for it..

Thanks!

[dicky96]

Re: ASRock H81 only powers on with 24 pin jumped

Hi
Now what makes you think the BIOS chip is toasted? Did you check any of the other things that need to happen before the CPU can start running code from the BIOS?

Anyway how can a board 'not power on' if it has a corrupt BOIS? Think about that... it would mean the CPU would have to be reading the corrupt BIOS before deciding to turn the board on. But how can the CPU read the BIOS when not powered yet? It can't therefore your assumption must be wrong.

Anyway First and foremost -
Which are these pin3&4 you are jumping? Please post some pics and also full model of the motherboard. It's likely I have a boardview file for it.

A few things you may as well check now: Do these in order shown below.

1. do you have any voltage on the PS_ON pins on the front panel header when the PSU is in standby?

2. also do you have any voltage on the front panel reset pins

3. Is the CMOS battery good, 3.0V or a bit more? Also measure the current draw from the CMOS battery, it's is often good indication of whether the Super IO and ICH are OK. You should have a few uA current draw from the battery - no more.

4. Is the RTC crystal oscillating?

5. take the heatsink off the northbridge (PCH, whatever its called) - check the voltage on all the capacitors on the BGA substrate, one side of each will be connected to ground. What did you find? You can try this with the PSU in standby and also when the PSU is forced on

6. Do you Vcore (voltage to the CPU from the VRMs) when you force the ATX PSU on? You can check this from the coils in the VRM circuits. There are known issues with certain Asrock motherboard chipsets displaying these type of faults. In particular is Vcore turning on and off every few seconds?

That will do to start - there are plenty other things to check once we have the answers to the above

[timma100]

Re: ASRock H81 only powers on with 24 pin jumped

When I say pins 3 and 4 I am referring to the pins in the attached picture.. 3.4V for front panel power, no voltage for front panel reset. Cmos batt is 2.9v. I'll get more info for you shortly

[timma100]

Re: ASRock H81 only powers on with 24 pin jumped

Hi
Now what makes you think the BIOS chip is toasted? Did you check any of the other things that need to happen before the CPU can start running code from the BIOS?

Anyway how can a board 'not power on' if it has a corrupt BOIS? Think about that... it would mean the CPU would have to be reading the corrupt BIOS before deciding to turn the board on. But how can the CPU read the BIOS when not powered yet? It can't therefore your assumption must be wrong.

Anyway First and foremost -
Which are these pin3&4 you are jumping? Please post some pics and also full model of the motherboard. It's likely I have a boardview file for it.

A few things you may as well check now: Do these in order shown below.

1. do you have any voltage on the PS_ON pins on the front panel header when the PSU is in standby?

2. also do you have any voltage on the front panel reset pins

3. Is the CMOS battery good, 3.0V or a bit more? Also measure the current draw from the CMOS battery, it's is often good indication of whether the Super IO and ICH are OK. You should have a few uA current draw from the battery - no more.

4. Is the RTC crystal oscillating?

5. take the heatsink off the northbridge (PCH, whatever its called) - check the voltage on all the capacitors on the BGA substrate, one side of each will be connected to ground. What did you find? You can try this with the PSU in standby and also when the PSU is forced on

6. Do you Vcore (voltage to the CPU from the VRMs) when you force the ATX PSU on? You can check this from the coils in the VRM circuits. There are known issues with certain Asrock motherboard chipsets displaying these type of faults. In particular is Vcore turning on and off every few seconds?

That will do to start - there are plenty other things to check once we have the answers to the above

1ua current draw from the cmos batt.. varies between 0/1/2

Also found some damage to the x16 pcie power pins

[timma100]

Re: ASRock H81 only powers on with 24 pin jumped

Hi
Now what makes you think the BIOS chip is toasted? Did you check any of the other things that need to happen before the CPU can start running code from the BIOS?

Anyway how can a board 'not power on' if it has a corrupt BOIS? Think about that... it would mean the CPU would have to be reading the corrupt BIOS before deciding to turn the board on. But how can the CPU read the BIOS when not powered yet? It can't therefore your assumption must be wrong.

Anyway First and foremost -
Which are these pin3&4 you are jumping? Please post some pics and also full model of the motherboard. It's likely I have a boardview file for it.

A few things you may as well check now: Do these in order shown below.

1. do you have any voltage on the PS_ON pins on the front panel header when the PSU is in standby?

2. also do you have any voltage on the front panel reset pins

3. Is the CMOS battery good, 3.0V or a bit more? Also measure the current draw from the CMOS battery, it's is often good indication of whether the Super IO and ICH are OK. You should have a few uA current draw from the battery - no more.

4. Is the RTC crystal oscillating?

5. take the heatsink off the northbridge (PCH, whatever its called) - check the voltage on all the capacitors on the BGA substrate, one side of each will be connected to ground. What did you find? You can try this with the PSU in standby and also when the PSU is forced on

6. Do you Vcore (voltage to the CPU from the VRMs) when you force the ATX PSU on? You can check this from the coils in the VRM circuits. There are known issues with certain Asrock motherboard chipsets displaying these type of faults. In particular is Vcore turning on and off every few seconds?

That will do to start - there are plenty other things to check once we have the answers to the above

PCH caps have no voltage, checked all surrounding SMDs..nothing. pch vrm toast?

[ChaosLegionnaire]

Re: ASRock H81 only powers on with 24 pin jumped

Also found some damage to the x16 pcie power pins

yea looks like the plastic part of the x16 slot melted, most probably due to a short circuit on the inserted video card somewhere. odd that could happen as the power limit of the slot should be 75w, so it should limit current even if there is a short circuit.

[dicky96]

Re: ASRock H81 only powers on with 24 pin jumped

1uA from the CMOS battery is a bit lower than normal but fair enough, it is not high. However at 2.9V the CMOS battery is probably pretty much drained - fit a new one and check current again

I would expect there to be 3.3V Standby on the SIO and ICH, maybe also PCH - but on some chipsets that standby could be 1.8V or 1.1V - so yes there could be a VRM near the chipset that has 3.3VSTB coming in but nothing going out (and is enabled so it should have output voltage)

Did you check resistance on all the chipset capacitors to ground? This will also tell you how many different voltage rails supply those chips have, probably three

Have a look at the pinout for PCIe - this should tell you which pins were overloaded if it has melted - which is does look like as ChaosLegoinnaire says - this could give you some idea of where VRMs could have been damaged on the motherboard

https://linustechtips.com/topic/9235...-do-they-work/

Can you give me full model number of the board? I probably have a board view file (if you don't already have one) and that could help a lot.

3.4V on the front panel start switch is good - possibly there is no voltage on Reset switch until the board power on

[timma100]

Re: ASRock H81 only powers on with 24 pin jumped

1uA from the CMOS battery is a bit lower than normal but fair enough, it is not high. However at 2.9V the CMOS battery is probably pretty much drained - fit a new one and check current again

I would expect there to be 3.3V Standby on the SIO and ICH, maybe also PCH - but on some chipsets that standby could be 1.8V or 1.1V - so yes there could be a VRM near the chipset that has 3.3VSTB coming in but nothing going out (and is enabled so it should have output voltage)

Did you check resistance on all the chipset capacitors to ground? This will also tell you how many different voltage rails supply those chips have, probably three

Have a look at the pinout for PCIe - this should tell you which pins were overloaded if it has melted - which is does look like as ChaosLegoinnaire says - this could give you some idea of where VRMs could have been damaged on the motherboard

https://linustechtips.com/topic/9235...-do-they-work/

Can you give me full model number of the board? I probably have a board view file (if you don't already have one) and that could help a lot.

3.4V on the front panel start switch is good - possibly there is no voltage on Reset switch until the board power on

Thank you for the help! Model number attached, sorry it's upsidedown I'm doing this from my phone. I'll check capacitor ground paths tonight and report back

[timma100]

Re: ASRock H81 only powers on with 24 pin jumped

1uA from the CMOS battery is a bit lower than normal but fair enough, it is not high. However at 2.9V the CMOS battery is probably pretty much drained - fit a new one and check current again

I would expect there to be 3.3V Standby on the SIO and ICH, maybe also PCH - but on some chipsets that standby could be 1.8V or 1.1V - so yes there could be a VRM near the chipset that has 3.3VSTB coming in but nothing going out (and is enabled so it should have output voltage)

Did you check resistance on all the chipset capacitors to ground? This will also tell you how many different voltage rails supply those chips have, probably three

Have a look at the pinout for PCIe - this should tell you which pins were overloaded if it has melted - which is does look like as ChaosLegoinnaire says - this could give you some idea of where VRMs could have been damaged on the motherboard

https://linustechtips.com/topic/9235...-do-they-work/

Can you give me full model number of the board? I probably have a board view file (if you don't already have one) and that could help a lot.

3.4V on the front panel start switch is good - possibly there is no voltage on Reset switch until the board power on

yea looks like the plastic part of the x16 slot melted, most probably due to a short circuit on the inserted video card somewhere. odd that could happen as the power limit of the slot should be 75w, so it should limit current even if there is a short circuit.

Working with the boardview and doing some troubleshooting... Found PQ717 (in the attached picture) has 3.3V input, PCH_DRV (Pin1) is 1.5V as it should be but PCH (Pin3) is only .4V... Could this be the bad Fet not letting the PCH power on?


OE PN:AP9452GG

[dicky96]

Re: ASRock H81 only powers on with 24 pin jumped

Good work!
Yes that would stop it from powering up

Actually I had a very similar problem on an X570 AM4 motherboard a couple weeks ago - in my case it was not a FET it was an LDO regulator, but basically same sort of problem. That one is now waiting for parts.

If the FET is getting warm/hot it could be a faulty PCH drawing too much current, so its worth checking the resistance from +1.5V_PCH to ground - but I guess you would have already said it is getting hot.

So if it has 5V coming in and only 0.7V going out, then really there are three options I can think of

1. Faulty FET
2. Wrong voltage on gate (resistor gone high or OC, leaky capacitor, faulty zener or similar situation)
3. Excessive load from PCH

[timma100]

Re: ASRock H81 only powers on with 24 pin jumped

Good work!
Yes that would stop it from powering up

Actually I had a very similar problem on an X570 AM4 motherboard a couple weeks ago - in my case it was not a FET it was an LDO regulator, but basically same sort of problem. That one is now waiting for parts.

If the FET is getting warm/hot it could be a faulty PCH drawing too much current, so its worth checking the resistance from +1.5V_PCH to ground - but I guess you would have already said it is getting hot.

So if it has 5V coming in and only 0.7V going out, then really there are three options I can think of

1. Faulty FET
2. Wrong voltage on gate (resistor gone high or OC, leaky capacitor, faulty zener or similar situation)
3. Excessive load from PCH

I thought the same thing about a short to ground for the PCM 1.5V.. Resistance to ground is roughly 5K ohm.. I don't know what the spec is but that should be alright.. do you know a reputable place to get good SMDs other than digikey? They don't carry this APEX fet.

Thanks again for the help! Going to give this a shot, and if it doesn't solve the issue, back to troubleshooting I go lol

[dicky96]

Re: ASRock H81 only powers on with 24 pin jumped

Just order one from Aliexpress and see if it works. That's what I do and apart from some power MOSFETs with the source and drain reveresed (they worked once I botched it to wire it hte other way round) and some 100V capacitors that broke down at 95V, I never had a problem.

I would suggest that 99% of components you can buy off Aliexpress are perfectly good - just a few 'high value' or 'high'demand' parts you might find some fakes