Dead SATA on Gigabyte

[rkchkr]

Here are the grim details. Board is a Gigabyte GA-7N400 Pro2. My son (mis)connected the power connector from the PSU to the floppy drive and let the smoke out of the wiring from the PSU. Took out the PSU ,the floppy drive and the SATA controllers. Fortunatly all the hard drives and the IDE and , I believe ,the floppy drive controllers survived. He had both IDE and SATA drives connected at the time ,and I believe the SATA drives were on the same PSU run as the floppy ,but luckily the SATA drives also survived. So we're left with no SATA controllers on the board. Upon close inspection ,I noticed one of the FET's near the SATA connectors appears to be bubbled/burned.(see pics) So my question(s) are ,what are the chances the FET is the only problem and if so ,could I rob one from another board to replace the burned one ,and what do I need to know as far as a proper replacement part is concerned if any of this is feasible at all? PS: I have a bad case of CRS ,so I'll talk to him tomorrow to see if I have all the correct details of the event ,and make any corrections then ,as the board has been laying around for several months since we replaced it with a SOYO KT880. Thanks much!

[gonzo0815]

Re: Dead SATA on Gigabyte

First i think Gigabyte are not that bad boards (despit some low quality caps), therefore i don`t think the root cause for this failure is the mosfet. Morover i think the number one component i would suspect there is probably the psu with dirty (e.g. bulged) caps. Passing to mutch ripple current to the motherboard will kill all components like hdd, caps controler and mosfeets, if the psu was getting out of regulation and has poor desing, even some overvoltage could be feed to the components. The obviously burnd mosfet is a kind of linear voltage regulater, e.g all excess voltage will be turned into heat. Therefore some ripple or overvoltage will kill it fast.
So i think you should quote your ATX psu specs including brand, model name, power output and the specified power output on each line.

If the board is running fine, then there is a good changse to fix it replacing the mosfet. But if the mosfet is shorted and has passed some high volltage to the following circuit may be there is more bad then this (e.g. the silicon immage Raid controler chip).

For replacement you should note the marking on the top of the chip, may be there is a datasheet around the net. Then you can looking for an suitable replacemnet.

Edit:
there is the link to the datasheet of this device:



May be you could find it at digikey or farnell. If not any similar logic level N channel mosfet will do.

And please remember, to unsolder this kind of devices you need a high wattage soldering iron. To get it removed very fast and without dammage of the pcb i suggest something in the 60 to 80w area and a chisel type of soldering tip.
If you heat to long, the pcb will delaminate or the new component will be fried.

[rkchkr]

Re: Dead SATA on Gigabyte

Thank you for taking the time to post gonzo. I haven't felt well the past week, and apparently I left out some pertinent details in my previous post. I think a bit of history as well as some clarification on my part is in order. The board in question was given to my son ,and was new/unused. He bought all new drives, RAM, CPU, PSU etc. The only used drive was the floppy. After assembling the system, all was working fine, except the floppy drive seemed to have some issues which later proved to be bad disks. In the mean time, he just swapped the floppy drive with another unit. Unfortunately in his haste, he incorrectly connected the power connection to the floppy drive, missing by one pin and apparently sending 5 volts to ground. OOPS! So I agree with you that there were definitely some over voltage issues!!! By the time the smoke from the power supply wiring had cleared and the PSU replaced with an ANTEC 500 watt unit and some checking for other casualties, we ended up with the "dead SATA controller" issue. Since your post, I have unsoldered the legs of the burned FET and tested it to see if it is shorted. It is not. However, being burned, I want to replace it and have looked up the data sheets on 2 other FET's I can hopefully use from another board. I'm new to all this and have no background in electronics to speak of, so if you would be so kind as to check these data sheets and let me know if either, or both would be a suitable replacement, it would be most appreciated. My fear is there will be other damage as you said, likely to the silicon image Raid controller chip, but I won't know until I try. Thank you for taking the time to find the data sheet for the burned FET, it was a great help in eliminating, as a replacement, some of the other FET's I have access to.

[rkchkr]

Re: Dead SATA on Gigabyte

anyone????

[arneson]

Re: Dead SATA on Gigabyte

I can only say I think your chance of success is fair to reasonable.
You were smart to notice the fet burn and swapping from another board with a close match is what I would also try.
This may not be the case in your situation but I usually see more than one fet go bad and like to pair them.