bad caps on gigabyte GA-7VR

[hawkeye1103]

well i had 3 bad caps,2-1200uF and one 1000uF all of them @ 6.3V know i face another problem it won't start
the caps worn't leakin just a little, more bent
this motherboard crashed a year ago or so, and i got another one then and now i tought it's time to fix it. so i changed the caps, they were corectly placed.

When the computer starts with this motherboard i noticed it gives a little jog to the cpu fan... besides from that nothing else

[hawkeye1103]

Re: bad caps on gigabyte GA-7VR

what can be the cause of this problem???

[shadow]

Re: bad caps on gigabyte GA-7VR

From what I have read on these forums, that does not sound very healthy at all. It sounds like the MOSFET's are dead or at least dying. This can be attributed to the bad capacitors.

If I were to save this motherboard, I would replace the capacitors (which you have, just realised) and at least test the MOSFET's, if the MOSFET's are dead than you will have to replace those as well. Only trouble with failed MOSFET's is they tend to kill other components in the system, things like CPU's, Northbridge/Southbridge chips, maybe graphics cards.

Maybe some other members can help you out some more. However I would test the MOSFET's with a digital multimeter before deciding whether to save this motherboard or not.

[hawkeye1103]

Re: bad caps on gigabyte GA-7VR

well i have no idea what mosfet's are (i'll google it) they can be dead ... the proc is still alive and the graphic card... no problems there .... i'll search and try to replace them... please help me with the mosfet's in case i can't find what those are:P

[hawkeye1103]

Re: bad caps on gigabyte GA-7VR

found em... on my motherboard they have one leg cut off but they don't show any sign of failure... not cracked or smth like that (i have one busted on my audio amplifier, and it blew up in 2 halfs) nothing like that here....can they just be busted???

ps: mosfet's = tranzistors right?

[dungbeetle]

Re: bad caps on gigabyte GA-7VR

I think they are metal oxide silicon field effect transistors...

[hawkeye1103]

Re: bad caps on gigabyte GA-7VR

yeah but what do they look like... i have some pics with my motherboard with the caps changed and a question... are those the mosfet's?
if not where are they:P

[dungbeetle]

Re: bad caps on gigabyte GA-7VR

Those 3-legged guys with the missing middle leg are most likely the MOSFETS. At least the ones I am familiar with were that package type.
Look here:
http://www.overclockers.com/tips1095/

The middle leg thats missing is the ground and those are soldered to the board and thus grounded that way.

[hawkeye1103]

Re: bad caps on gigabyte GA-7VR

aha 10x a lot well i'll search for mosfet's like those ... see if i can find any....if not i'm done 4... i guessed the mosfet's were done 2 because of the color of the mother board....u can see it's that greenish blue.... whell on the other side where some mosfets are and where the caps are it's gotten green (from the head i guess, there is no other reason) i'll change em all and do another test.

PS if i solder the middle leg where the mosfet is now it will work fine:-?... it sounds reasonable... if i can't desolder the back of the mosfet's

[dungbeetle]

Re: bad caps on gigabyte GA-7VR

Not sure as I have never done it but I have seen a post with pics from someone who has. He soldered it like the originals so he would be a better help than me. If I run across it I will give you the link. If anyone else knows the link feel free to help

[dungbeetle]

Re: bad caps on gigabyte GA-7VR

Some related in but not he pics I was looking for. May be useful though.
https://www.badcaps.net/forum/showth...MOSFET+replace

https://www.badcaps.net/forum/showth...&highlight=FET

[starfury1]

Re: bad caps on gigabyte GA-7VR

Well not sure what the state of the PCB is, look like the mosfets were getting nice and hot and could well be stuffed

Generally

Ideally replace all caps of same type (and value) and replace any that are on the badcaps list of baddies

If there any GSC get rid of them asap

Mosfets can cook, do the test with multimeter to be sure.
Haven't got a decent link to hand but there are posts here on it

here one on it thought



They can be a pain to remove there are a few posts on it.

If they are stuffed cut the two little legs with nippy cutters near the body
(careful not to cut pcb, remove the legs off pads later)

Ideally for the Tab a nice heavy duty hot iron (60~80w see posts)


Hold body with small pliers or tweezers flow a bit of solder on tab to help with heat transfer pick it off when solder goes molten
Thats the hard part

....hot and fast is the name of the game.

If you use a low wattage iron (15 ~25w) you will probably not do the job, just possibly damaged the pcb

Practice on junk if you haven't done it before.

There are tools that make it easier but $$$$

if it were just caps and BSOD and hangs, there would be a very good chance of no problems but as pointed out mosfet could cause other damage
(leave open to those that know more on that)

Mosfet is a type of transistor

It what is know as a Field Effect transistor,. this case metal-oxide-semiconductor field-effect transistor.

These are Voltage controlled devices were as Bipolar are current controlled devices Wili
mosfet

Helps if you understand electronics basics

There is heaps of info out there and posts on how to test here somewhere

HTH

[hardwareguy]

Re: bad caps on gigabyte GA-7VR

If the only sign of power is a twitch of a fan, that usually means the PSU has shutdown due to a short circuit. I usually decide to chuck boards that have shorted, unless it's an ultra expensive proprietary job, I won't touch a shorted board. I might fiddle with an Itanium board, a quad CPU board or a nice fancy SGI, but that's about it.

To this day I have not had any boards come in that were so expensive they were worth the customer paying me to find out why they shorted and fix them. In Texas, the most common cause for a shorted motherboard is the wrath of mother nature; the motherboard isn't the only thing shorted or charred.... this of course makes me money selling them a new PC or better yet, a server!

[hawkeye1103]

Re: bad caps on gigabyte GA-7VR

well 10q all ... but let me explain what happened maybe it means smthing 2u ... the first time i tought the source shorted.... so i changed the source after getting the new source in the computer i saw that it was still not working after that i saw that the motherboard and the source were fried so i changed them both...the fuse in the source was fried and smth else that was shorting in 2 times in a row