Asrock H61M-GS no power

[rippergr]

Hello all,
I have a pc motherboard asrock h61m which doesnt post at all.
I connect new PSU still nothing.
I remove the cmos battery for 24 hours and reset it , still no power.
The CPU fan seems to make a very little motion as is trying to start but nothing else.
Can someone guide me what should I first check? I dont have previous experience on repairing PC motherboard I only repair notebook motherboards in chip level.
P.S. The motherboard has oonly solid capacitors so There is no visual defective capacitors or any other visual defective component.

[selldoor]

Re: Asrock H61M-GS no power

Good clear pictures of the board?

[rippergr]

Re: Asrock H61M-GS no power

I dont think pictures will be any helpful because all the board is like brand new. There is nothing that seems bad visualy.

[pfrcom]

Re: Asrock H61M-GS no power

Which processor ?

On Asrock's CPU Support List ?

[c_hegge]

Re: Asrock H61M-GS no power

Do you mean that the CPU and PSU fans briefly twitch when you attempt to power it up? If so, try unplugging the 4/8 pin ATX12V connector. It won't POST that way, but if it powers on, then you know it's the CPU VRM that's shorted.

[rippergr]

Re: Asrock H61M-GS no power

Yes the cpu fan makes a little twich. I tried without the 4 pin connector but it still doesnt post.
Can you tell me where is the CPU VRM and how to check ?

[c_hegge]

Re: Asrock H61M-GS no power

Does it power on at all with the CPU connector unplugged, or does it still just do the fan twitch?

Remember, there is a big difference between powering on and POSTing.

The CPU VRM is the area of the board in your 4th picture.

[rippergr]

Re: Asrock H61M-GS no power

No it doesnt power on at all. It's like dead.
only this tiny movement for a split second of the fan and nothing else.
Do I have to check all components there? and if yes how can I check it?

[c_hegge]

Re: Asrock H61M-GS no power

One thing I have noticed there is that your CMOS battery is installed backwards. That - may - be part of the problem.

The first thing I would do is see which rail the short occurs on. That little test I just suggested pretty much rules out the CPU VRM area as the source of the problem. Set your DDM to resistance, and check the resistance between the rails (12V, 5V, 3.3V, -12V) and Ground. If any of them is shorted to ground then that will further narrow it down. In all likelihood, it will be a transistor somewhere.

[rippergr]

Re: Asrock H61M-GS no power

You are right with the battery, I just remove it to make motherboard reset and I just left it there when I took the pictures.
I checked the rail with my multimeter in buzzer and all the com are buzzing and all the other pins are not so I suppose I don't have a short.
I checked some of the mosfets in the 4th picture and in some I have resistance(buzzer) in two pins and in some only on the head . Is this normal?

[selldoor]

Re: Asrock H61M-GS no power

One thing I have noticed there is that your CMOS battery is installed backwards. That - may - be part of the problem.

Good Spot that .

I checked some of the mosfets in the 4th picture and in some I have resistance(buzzer) in two pins and in some only on the head . Is this normal

You should give result in ohms Bad is usually less than 30ohms but it would still buzz
Mosfets
---------

If you have a manual range multimeter, set it to 200 ohms (two hundred). You can test a mosfet (Q, IC designation) "in circuit" by (power off and unplugged)

a) black on pin 1- red on pin 2 - record ohms
b) black on pin 1- red on pin 3 - record ohms
c) black on pin 2- red on pin 3 - record ohms

If any ohm reading is less than 30 ohm you might have shorted mosfet. Remove from circuit and repeat the tests to verify.

Some mosfets are more than 3 pins. To test those, identify the part number and search for its datasheet. Once you find the datasheet, the pins will be designated source (S), gate (G), and drain (D). It will probably be documented as S1, S2, G1, G2, D1, D2.

Simply test

a) black on pin S1- red on pin G1 - record ohms
b) black on pin S1- red on pin D1 - record ohms
c) black on pin G1- red on pin D1 - record ohms

Repeat for the "2" pins. That is S2-G2, S2-D2, G2-D2.

[rippergr]

Re: Asrock H61M-GS no power

most of the mosfets are show infinite or under 30 ohms.(readings are in circuit)
Does this mean that all are shorted?
There are 14 mosfet near CPU do I have to remove them all to test them?

[c_hegge]

Re: Asrock H61M-GS no power

^
The MOSFETS around the CPU are unlikely to be the problem. As I said, the test where you attempt to power the board up without the CPU connector plugged in rules that area of the board out.

The problem is more likely to be on the RAM or Chipset VRM, or maybe even one of the peripheral controllers (like the Network controller)

[rippergr]

Re: Asrock H61M-GS no power

I remove RAM as well but still no power. Can I start checking some components excluding some others? for example how can I check the chipset VRM or network controller?

[c_hegge]

Re: Asrock H61M-GS no power

I actually meant the VRM the RAM. You'll need to check the MOSFETs on said VRMs using the procedures outlined.

As for the network controller, I'm not too sure how you would test it. I only suggested it as I've revived a couple of boards which were victims of lightning strikes through the network by removing the network controller IC.

[rippergr]

Re: Asrock H61M-GS no power

Do you have schematics for this board? or can you point me where is the VRM of RAM

[momaka]

Re: Asrock H61M-GS no power

I've seen something similar happen with a Gigabyte UD3 board before and it wasn't a shorted MOSFET.

So try this: plug PSU in board and short the PSU's PS-ON wire to com/ground. Usually, PS-ON is a green wire, and ground is black. If PSU fan twitches and does nothing again, you have a short circuit.

Another thing I notice is you have some stuff plugged in the USB ports. Makre sure to remove those for the tests and also inspect all USB ports for bad pins.

Last and most important - before we get deeper into the motherboard circuitry - what name and brand of power supply are you using? If it's not under warranty, can we see some pictures of the insides of it?