7900GT "dead" ?!

hi there

i modded the 7900GT board which i ve done correctly, but i got lazy and didnt check the 10kohm vr exactly only turned to full resistance, but this poti was damaged and now the card is, its a vmem mosfet i got a nice pic of it, its half burned on one site i cant read the numbers exactly for datasheet, but i think it is 4420 - BD6B12 or something

i m good in soldering so if it s possible i can do it but i m not that good in electronics so what chance i got?

i know theres was going a lot of volts through it so maybe the gddr memory is damaged too but i dunno exactly

thanks in advance!

so thanks to SF3D i know now how the chip is called

4420 BE6A15

i cant find a datasheet for it maybe you can help me searching would be great i try to ask my eletronic dealer about the mosfet, thx

on my gainwad reference card it's a
4420
BE6B11

and the logo on it looks like a fancy AP

maybe this batch has a new one due to problems with your one
my pcb has 0906 as the date stamp just above the 'made in taiwan'

hmmm thx for information but that didnt make things clear/easier for me :)

i dunno much about electronics so that is definetly a bit difficult.

i found no datasheet for 4420 BE6A15 or 4420 BE6B11 just found this but dont know if its any good....lol

http://www.datasheetcatalog.net/cgi-....pl?text=4420B

to make this clear the card had no problems @ all i just soldered a damaged 10kohm vr for the vmem and i was not paying attention i didnt measure the ohms before soldering, thats what billy would call a "fatal_error".


seEn and thx again

if you can locate one of those things you might be able to fix it.
it basically depends whether the ram blew first or if that IC blew and maybe protected the ram.

unfortunately locating another dead 7900gt for spares is going to be difficult as it seems fairly likely it will have died for the same reason.
however you may get lucky or even find a suitable component from some electronics distributor.
if you find a replacement i doubt it will be expensive so it would be worth a try imo

was the screen on when it died and did you see artifacts?

that IC has gone like that twice on this forum..whats the deal? how to prevent this? lol im starting to worry, i got the 1.5 vmod with a zalman 700cu onit with a PCI fan card on the whole front side of board (so not the back where the IC lie) but i good decent airflow.

thx flytek i hope ure right, and i think also its worth a try!

ironetik you dont have to be afraid my damaged 10kohmvr is was jumping from 1kohm to 10kohm....

and i didnt do anything at all i just bootet the system there was no pic for 2-3secs i had i bad feeling because board hang also....and when i wanted to turn offthe psu i saw some cloud flying behind the card then i saw what it was.

That is the same IC the caught flame on my 7900GT after the vmem mod. However it burned up so badly that it melted much of the things around it. lol

hmmm yeah i also though about that it maybe burned the chip besides a bit.

we ll see...

i got the card on the same day i damaged it.... it was stock 450/1320 and i got up to 560/1600 (mem not maxed) with stock cooler 63Cmax. so wanted to oc it a bit more ;)

so i m sry to hear your card is gone too, i know you was waorkin hard here for getting the mods.

seEn

so i cant get the ic here in an electronics shop,
cant get the specs of the ic...
"sh33t"


as far as i see only chance is to get an other damaged card with this ic working and soldering on the other card.... like from 2 do 1

:( bummer man. GL with your search.

what mthod of vmod did you try?

Not to spread salt in your wounds but placing a resistor after the potentiomter to get a max possible voltage is a very good idea, just something for others reading this to keep in mind...

And also for the ones who pencil mod their cards without calculating what the new voltage with be using a multimeter, this is what will happen...

i know i ve soldered many things....

i took the time and the mods were good but thats the only thing i forgot or i was too lazy for to measure the vr again, well just see the good site i ll sure NEVER forget measuring it again :D

the idea with the resistor between is a good one :thumbsup:

seEn

andL64, do you mind if I use your pic as an example in my guide over at extremeoverclocking so that my readers there can see what would happen if they try the pencil mod and don't care to buy a multimeter. Here's a link to my guide which is on post #4.

ygpm

That has because the vmem mod? how many voltage you were giving to those mems? :3

i dunno but it was sure a lot if i didnt got a screen on bootup so i think it OVP kicked in but the little IC cant hold it and blewed up.

seEn

try removing it entirely. it looks like there are two of those chips in paralell. might just double up the load on the second one (which might blow that chip too) and make it work. either way, you have to remove the burned chip.

sorry for the loss :(

I did the pencil mod and I got it to 553 ohms exactly but I haven't measured the voltage yet..i need someone to hold my heatsink fan up while i do it, anyone want to come to my house? lol jk...i cant get to the vmem measure point otherwise :( STUPID XP-120! lol

Quote:

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Originally Posted by iRoNeTiK

I did the pencil mod and I got it to 553 ohms exactly but I haven't measured the voltage yet..i need someone to hold my heatsink fan up while i do it, anyone want to come to my house? lol jk...i cant get to the vmem measure point otherwise :( STUPID XP-120! lol

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Just solder a wire to the measure point so you get easier access too it?

Quote:

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Originally Posted by cirthix

try removing it entirely. it looks like there are two of those chips in paralell. might just double up the load on the second one (which might blow that chip too) and make it work. either way, you have to remove the burned chip.

sorry for the loss :(

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The component that is destroyed is a N Channel Mosfet.
It is one of four switches of the two phase bucket convertor.
A replacement part is the IRF7821PBF costing roughly $1,-.
There are no chips in parallel, but there is a second 4420 that should also be replaced to keep things in balance.
One could even replace all four Mosfets with the IRF7821PBF if they are suspect.
I hope that this is all that is damaged, although I fear that the 7900 GPU had a voltage applied that was much too high.
AndL64, where the hell did you connect the 10K VR to. This was wrong from the beginning, since the 7900 should be modded differently.

Quote:

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Originally Posted by t024484

The component that is destroyed is a N Channel Mosfet.
It is one of four switches of the two phase bucket convertor.
A replacement part is the IRF7821PBF costing roughly $1,-.
There are no chips in parallel, but there is a second 4420 that should also be replaced to keep things in balance.
One could even replace all four Mosfets with the IRF7821PBF if they are suspect.
I hope that this is all that is damaged, although I fear that the 7900 GPU had a voltage applied that was much too high.
AndL64, where the hell did you connect the 10K VR to. This was wrong from the beginning, since the 7900 should be modded differently.

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hmm thats good news, first....

u said there s an other 4420 do you mean the chip besides? here its 4410 and 4420...if you mean it
i ll get the mosfet tomorrow and see what i can do :)

heres the pic where you see the mod i did and which pic i used:

Quote:

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Originally Posted by iRoNeTiK

I did the pencil mod and I got it to 553 ohms exactly but I haven't measured the voltage yet..i need someone to hold my heatsink fan up while i do it, anyone want to come to my house? lol jk...i cant get to the vmem measure point otherwise :( STUPID XP-120! lol

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i cut a molex from psu stick it on the end of the card and solder the measure point to the wire just stick in multimeter on the upside and voila no problms and best method :D

Quote:

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Originally Posted by andL64

hmm thats good news, first....

u said there s an other 4420 do you mean the chip besides? here its 4410 and 4420...if you mean it
i ll get the mosfet tomorrow and see what i can do :)

heres the pic where you see the mod i did and which pic i used:

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I did not interprete your picture correctly yesterday since it only displayed a very small part of your board, and I assumed it was the Vgpu that you had modded.
Having a better picture now, I can see that it was the Vmem that you tried to mod, and hence the 10K Vr that you used.

Since I am abroad at the moment, I cannot see the part nr of the voltage regulator (U501) , so please tell me this part nr.
With this part nr I can see if this voltage regulator is using two N channel Mosfets or a complementary pair of Mosfets and give you the proper advise.

Forget what I told you before about the four Mosfets and the possible damage to the GPU.

the vgpu mod i did very easy and it worked for sure fine i just connected a wire (all other people used the conductive INK) to solder between the 2 spots i m sure you know what picture i mean, thats the 1,4V vgpu mod

and the other one with the vaiable resistor was the vmem like in the picture above.

just found U502 the ISL chip, i cant find the U501, where sould it be located?

think only voltage regulator is the ISL chip located U502

ISL 6568 ( last 8 could be a B bout i doubt)
CRZ
N601RJ

edit: lol, electronics dealer is unable to find the IRF7821PBF N channel mosfet... omfg i think i need an other dealer he knows as much as me bout electronics :D

LOL ok checked again exactly , sry was my fault heres the U501: :D

U501:

6549CBZ
P605BKB

Quote:

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Originally Posted by andL64

LOL ok checked again exactly , sry was my fault heres the U501: :D

U501:

6549CBZ
P605BKB

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It is the ISL6549 Bucket Regulator, using two N channel Mosfets.
Replace both Mosfets (Q501 and Q502) with the IRF7821PBF.

hey look here thats what i foudn on alldatasheet.com

http://www.datasheetcatalog.net/cgi-...&action=Search

its just IRF7821 or IRF7821TR
or
IRLR7821PBF and IRLU7821PBF

this is again a noobish question but as i said i dunno which is the right one :D sry
the exact one like you said IRF7821PBF i cant find on alldatasheet.com and my dealer also dont in catalog *ooops*

thanks a lot again youre xtreme :P :D

Quote:

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Originally Posted by andL64

hey look here thats what i foudn on alldatasheet.com

http://www.datasheetcatalog.net/cgi-...&action=Search

its just IRF7821 or IRF7821TR
or
IRLR7821PBF and IRLU7821PBF

this is again a noobish question but as i said i dunno which is the right one :D sry
the exact one like you said IRF7821PBF i cant find on alldatasheet.com and my dealer also dont in catalog *ooops*

thanks a lot again youre xtreme :P :D

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IRF7821 and IRF7821PBF are basically the same, but the latter is leadfree on its external pins according to new regulations.

See what you can get, it makes no difference.

i checked the connections on the ones you need to replace.
on one side all legs are connected to the large silver plane and on the other side 3 legs are connected to ground.
the last leg goes somewhere else.
so soldering will be easier than it looks

i soldered many things but didnt solder 2 mosfets off the board and 2 on again :D well we will see how skilled i am *lol*

i will thank you all again a lot for this great help and knowledge but i think now its my turn!

i ll see if i can get the mosfet and try it out!

Quote:

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Originally Posted by andL64

i soldered many things but didnt solder 2 mosfets off the board and 2 on again :D well we will see how skilled i am *lol*

i will thank you all again a lot for this great help and knowledge but i think now its my turn!

i ll see if i can get the mosfet and try it out!

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Let me know if you are unable to get the Mosfets.
Succes

lol, i asked 2 big electronic companys here and my little dealer nobody has got them in stock, but they could get them i think....

its a shame that i m unable to get some little mosfet in vienna :D thats austria, well i see what i ccan do maybe i ll order 2 pieces?!

or did you got some t024484?

andL

found a shop here but only with this one:

IRLR7821

but it has not 8 legs...

Quote:

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Originally Posted by andL64

found a shop here but only with this one:

IRLR7821

but it has not 8 legs...

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You could use them to test if your board is still O.K.
But you have to be a little inventive since the gate is on the left side and your board expects the gate to be on the right side.
The single source pin is on the right side and is expected to be on the three left pins on your board.
But for a quick experiment they are very usable. If everything works as it should, you can always switch them for the IRF7821.

Quote:

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Originally Posted by t024484

You could use them to test if your board is still O.K.
But you have to be a little inventive since the gate is on the left side and your board expects the gate to be on the right side.
The single source pin is on the right side and is expected to be on the three left pins on your board.
But for a quick experiment they are very usable. If everything works as it should, you can always switch them for the IRF7821.

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ok i get flytek's description.... with the silver plane and the others grounded.

i cant understand your post,

well problem is i cant understand how the mosfet should be soldered on, which pin where, you know.

if i understand correct its like this?!

broken mosfet:
red ones are ground
blue one i dunno = silver plane
yellow one = dunno

do you mean the one side of the mosfet IRLR7821 with one broad pin (gate?) should be connected to the silver plate? (blue ones of the broken?)

but which of the other ones goes the the 3 red ones (on broken one)? the green or the red of the IRLR7821,

and whats about the yellow one on the broken mosfet and the blue short one on the IRLR?

the picture is just *lol* sry like my little brother drawed it ;)

picture:

Quote:

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Originally Posted by andL64

ok i get flytek's description.... with the silver plane and the others grounded.

i cant understand your post,

well problem is i cant understand how the mosfet should be soldered on, which pin where, you know.

if i understand correct its like this?!

broken mosfet:
red ones are ground
blue one i dunno = silver plane
yellow one = dunno

do you mean the one side of the mosfet IRLR7821 with one broad pin (gate?) should be connected to the silver plate? (blue ones of the broken?)

but which of the other ones goes the the 3 red ones (on broken one)? the green or the red of the IRLR7821,

and whats about the yellow one on the broken mosfet and the blue short one on the IRLR?

the picture is just *lol* sry like my little brother drawed it

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The large metal backplate on the IRLR is the drain and should be connected to the metal surface where you have drawed 4 bue pins.
The source is the right pin of the IRLR and should be connected to the three red pins.
The gate is the left pin of the IRLR and shoud be connected to the single yellow pin in your drawing.

P.S. Don´t say sorry for your little brother, he did a good job.

hey thanks thats absolute clear :D

lol, i drawed it! not my brother so i said lol because it really looks funny just very quick drawed, so it looks like painted by a little kid ;)

so did you get the parts you needed?
i can't wait for you to get the card going again :D

0502 is the same but 0501 is slightly different on my MSI NX7900GT, I cant check it as it was sold today (upgrading already/again :rolleyes: :D ) but I will check with the buyer and post back with the exact details/fet seriel numbers :)

Ok the 0501 chip on the MSI NX7900GT is slightly different

This one says :
32N03S
GAA604

and its a diff shape.

Are other cards the same ????