Help with a Maximus IV Extreme Z and two mosfets (??)

[Uazzamerican]

Hi all,
this is my first thread aasking for help.
Any of kind of advice is appreciate.

I stumbled across a Maximus IV Extreme-Z, apparently dead.
The LED activity is on if I conncet cables, but ON button won't work.
The chipset area is really hot so I think that the problem could be here, so I removed the heatsink and I see two bad little things.
Someone says that they are damaged mosfets that can be replaced but I really don' t know much about it.

On this photo you can see them, the one on the bottom appears to be marked as "43t", judging by Others similar across the board.





The other one on the left of the photo appears to be burned,or so I think, and I am unable to identify it.
Here is a better photo:




I would gladly attempt a replacement but I need to know what to search for...

Thank you.

[Uazzamerican]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

Some news.

With some precious help, now I can say that both the "things" damaged are labeled "43t".

Someone said to me to watch this page:
http://www.s-manuals.com/smd/43

There I can see that they seem to be "Schottky diodes", model number BAT54CW or BAS40.
Wich one I am not able to tell. I can't even tell what I have written so far...

I only need to know what I have to order to try a micro soldering.

Anyone?

[Uazzamerican]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

Anyone?

[momaka]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

Do you have a multimeter and do you know how to use it? I think this motherboard repair will take more than just replacing those two SOT-23 MOSFET-like components.

Speaking of which, are you sure they say "43t" on top of them and not "431"? Because 431 is commonly a shunt regulator, usually used to regulate a voltage rail for the chipset(s) and/or RAM. If the voltage going to the chipset is not right, that could well be causing it to overheat (and in which case, it will likely be dead too... bet let's not assume the worst for now.)

[Uazzamerican]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

I can say the are Schottky diodes, for two reasons:

another motherboard that is exactly the same (the Maximus IV Extreme, not Z) in the same place has a diode labeld l43, so is a Schottky.

and I can say it is 43t because there are a lot similar mosfet with that tag and no one that is 431.

[momaka]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

I can say the are Schottky diodes, for two reasons:

another motherboard that is exactly the same (the Maximus IV Extreme, not Z) in the same place has a diode labeld l43, so is a Schottky.

Ah okay. It's good that you have another working board like that. Makes finding parts info a lot easier.

Searching for "L43 SOT-23", I get this:
https://cdn.badcaps-static.com/pdfs/...dd644e0f1a.pdf
and this:

which implies that it is a BAT54C schottky diode (with common cathode on pin 3).

Now the question is to what do these schottky diodes connect and why did they blow?

You can certainly just replace them and see what happens. However, if you do that, I strongly advise to buy a few extra ones, just in case there are other problems on the board and they blow again.

[Uazzamerican]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

Thank you Momaka for your findings, you helped me a lot.
In fact I was thinking of getting some of those diodes.
Now I have to find a lab with precision soldering service here in Milano.
I can do it myself but I have not the tools.
My hand is pretty steady.
I see some soldering stations on Ebay for less than 20€... They scare me...

Plus I don't know how to use a multimeter neither I know why I should use it!

[momaka]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

Now I have to find a lab with precision soldering service here in Milano.
I can do it myself but I have not the tools.
My hand is pretty steady.

You don't really need hot air or any other specialty tools for this, actually. A regular 25-40 Watt iron will do. I solder SOT-23 parts like that all the time. The key is to modify the iron tip so that it has a spoon-like shape rather than a pencil or chisel. This works best with pure copper tips. Don't sand brass tips.
The only three things besides the iron that you will need is solder (of course), separate soldering flux, and fine tweezers to hold the part while soldering. IPA (Isopropyl Alcohol) is also recommended for cleaning up the board.

I see some soldering stations on Ebay for less than 20€... They scare me...

Some of the cheap ones are not that bad. But overall, it is probably best to avoid them - at least in my opinion.

Plus I don't know how to use a multimeter neither I know why I should use it!

Well in that case, don't. But if the motherboard doesn't work even after you replace those schottky diodes, then you probably will need a multimeter.
Don't worry, using one is not too complicated, especially if you are being given directions .

[Uazzamerican]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

Update:

Someone changed for me the diodes, the work is apparently well done.
Now if I plug the power cord the Chipset stays cold, which is good.

BUT:

Things are worse:

Now There is no more stand by led activity (the slow pulsating ROG symbol), the only thing I see is the rapid blinking of "bios 1" LED althogether with the stand by LED. Nothing more.

I can't switch from bioses anymore, can do nothing.

Someone on the net says that this behaviour is due to some kind of short, but I am on a cardboard and even stripped all the metal I could from the motherboard (even all the heatspreaders, just to try).
Nothing at all, only bios 1 rapidly blinking (and ROG LED).

I am at a loss.

[Uazzamerican]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

Plus,
Maybe I need a multimeter and some directions on how to use it.
Does this model is enough?

http://www.amazon.it/Hama-Multimetro.../dp/B000VE5QPY

[Uazzamerican]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

From what I have learned (not much...) from here:
http://www.google.com/patents/US7747884

The diode should be connected via the catode to a South bridge.

Connecting all power cables (or even connecting the 24 pin ATX plug only)
I notice that the little thing is VERY HOT, maybe the circuit is broken at some level past the diode?

Now, I assume this:

A) Before replacing diodes
With the psu cables plugged in, there was no way to power the motherboard, all I see was the ROG activity led normally bleeping and I was able to flash the bios with the ROG connection and a laptop, it's a ROG exclusive feature. I was able to switch from bios1 to bios2.
The Whole Z68 chipset was really HOT.

B) After the diodes replacement
With PSU cables plugged, no power to motherboard, I obtain only the rapid blinking of bios1 led togheter with blinking of ROG activity led, as I stated it seems to be a signal of some short on the motherboard.
The 43t diode "south of" the Z68 chipset is really HOT, the Z68 chipset is cold.

I can see an electric trace going from the diode's catode to the Z68 chipset (left of the Yellow mark)....

Don't know if this make sense

[Uazzamerican]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

Update.

Changing the PSU, from a Corsair HX520 to a Seasonic S12 600, the Diode 43t blowed up.
Now there is the same condition as before...

So it's definitely not the diode, but something above or beyond it.
I really can't tell what. Giving up....

[psychophat]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

There is no Maximus IV Extreme Z, it's either Maximus IV Extreme or Maximus IV Gene-Z. I have both what part of it are you looking for. I can post you an actual reference shot of the area.

[Uazzamerican]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

There is no Maximus IV Extreme Z, it's either Maximus IV Extreme or Maximus IV Gene-Z. I have both what part of it are you looking for. I can post you an actual reference shot of the area.

Thank you psychopat, but I can assure you that I am not getting completely mad and that my hardware knowledge is pretty solid.
Double check your findings and you will be able to see the Maximus IV Extreme Z.



http://www.hardwaresecrets.com/asus-...z-motherboard/

http://www.newegg.com/Product/Produc...82E16813131760

https://www.asus.com/it/Motherboards...S_IV_EXTREMEZ/

[psychophat]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

My bad with the model thinggy, going back you need to test the surrounding components. As momaka mentioned you definitely need a multimeter a cheap one will do as long as you can check volt and continuity (basic needs). When my Extreme 4 burned, I had to remove the 4th DDR3 slot remove most of the fuses, caps, controller and etc. Test individually if bound for replacing and then soldering back, tough ordeal but perseverance pays off.

Currently I'm like you, got two boards a Gene and Extreme both came out of storage just a month ago, to try ASUS for repair service again which was denied again of course, so am doing the repair work myself again and still waiting for parts (shipping is the killer).

[Uazzamerican]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

Unfortunately I am no electronic expert, neither a novice.
I am totally noob, I can't even tell I can use a multimeter.

[pcmaker]

Re: Help with a Maximus IV Extreme Z and two mosfets (??)

The burnt semiconductor is the result. It's not the cause. The cause must be removed. I saw the chipset, where I shorted one miniature ceramic capacitor. It was enough to connect the voltage from the laboratory source to the chips and set the current limit to 3A. The ceramic condenser has evaporated itself. I scraped it with a toothpick. MB works so far.