do Iahve a bad PSU or MB?.

**neon_eddy** · 03-02-2005, 03:24 PM

yeah I I decided I needed a few case fans.. so Ispliced soem into my normal case fan plug.. and I thought I taped up all the bare ends.. but I missed one set.. and it touched my hard drive... and it still was working oddly.. I beleive it was my +5v line ..

it melted the red wire of the 3 (red yellow black) .. but now it will still POST, and if I monitor the ahrdware it shows my 12v line at 10.5 or 11v .. and a cd-rom drive will power up on the board.. but no hard drive.. I tried on thatw as not on the system before too..

I can only imagine that something burned out.. maybe a cap or something.. I'm hoping I could find it and fix it.. anyone have any ideas?

**jcdillin** · 03-02-2005, 03:29 PM

well if the motherboard is still posting then you probably roasted your PSU and hard drive

I would try it with a diffrent power supply and see if your current drive still works.

**neon_eddy** · 03-02-2005, 04:41 PM

I just checked the hard drive.. and it spins up fine on my home system..

anyone good with electronics might know what burned out?.. to me it seems like the only issue is the 12v line is a little low..

**KyferEz** · 03-02-2005, 04:59 PM

The case of the HD is ground, and the red wire is usually 5v. Take a tester and test to see if the red wire is outputting 5v.

The 5v line is likely toast. There are likely drive output fets and maybe a fuse on the output that blew. I don't have one, so I can't tell for sure...

But what is weird is that the Mobo still posts; I wouldn't think it would do that w/o 5v. You really need to test all the lines to see which ones have voltage, and how much.

KyferEz

**neon_eddy** · 03-02-2005, 05:39 PM

ok I'll take a look..

I have a m1-ATX PSU .. great little guys..

**neon_eddy** · 03-02-2005, 06:37 PM

ok I looked closer at my PSU.. yup.. roasted and toasted..

however I used a 6v LED on my 5v line.. and it lit up fine.. and like I said a CD-ROM drive powers up fine on this system..

Heres the image

ANyone know a way to work around this.. I don't even know what this does exactly.. the part that burned out.. it's part Q2 on the schematic .. but I can't find anything on what it does exactly.. I also noted.. and you can look in the image.. there are 3 pins on each side that all are coming from the same trace .. I'm wondering if it is just a power cleaner or something.. and can be by passed .. any Electrical Engineers here?.. anyone... buhler?.. buhler?..

-shawn

**rando** · 03-02-2005, 06:50 PM

FDS9435A

http://www.fairchildsemi.com/pf/FD/FDS9435A.html

It's a FET. I don't know if it's being used as a simple switch or as the switcher for the DC/DC conversion. It shouldn't be too hard to replace it yourself -- though there may be other damage. Unhook the PSU and manually test it out. What voltages do you get on each of the rails?

You migh tray talking to Andrewb also. I'm sure he'll be interested to understand the failure mode and might be able to repair it for you.

**neon_eddy** · 03-02-2005, 08:32 PM

thank you very much ...

from what I can see, it looks like a diode basicly.. that protects against power coming back teh other way ... it looks like there is a gate of soemkind also.. but that is never closed because the pin is left open on this board.. just my .02

I'll ask Andrewb

thanks.. anyone else who might have any suggestions I'm up for them!

**neon_eddy** · 03-03-2005, 07:10 PM

FIXED!!!!!..

all it needed was a new Power Trench thingy.. I pulled one from my busted PW-70A ..

thanks for everyone's help.. couldn't have ben done with out everyone!

cheers..