Hello,
My friend got his MB toasted. I was able to identify, which part is
burnt, but i am unable to read the part number. I hope that there is
someone, who has such a mainboard and will be able to tell me, what part
am I looking for. I need to know the exact symbol to replace this element.

The mainboard image with the damaged element marked is here:
http://img528.imageshack.us/img528/2157/pc0400881zu.jpg

And here is the closer look:
http://img528.imageshack.us/img528/6697/pc0400925xf.jpg

Thanks in advance, I will appreciate any help

--
Best Regards,
Darek

"Darek" <(E-Mail Removed)> wrote in message
news:dn27mg$og0$(E-Mail Removed)...
> Hello,
> My friend got his MB toasted. I was able to identify, which part is
> burnt, but i am unable to read the part number. I hope that there is
> someone, who has such a mainboard and will be able to tell me, what
> part am I looking for. I need to know the exact symbol to replace this
> element.
>
> The mainboard image with the damaged element marked is here:
> http://img528.imageshack.us/img528/2157/pc0400881zu.jpg
>
> And here is the closer look:
> http://img528.imageshack.us/img528/6697/pc0400925xf.jpg
>
> Thanks in advance, I will appreciate any help
>
> --
> Best Regards,
> Darek

You are on the proverbial fool's mission. There is 100% probability
that there is other hidden damage to the board. Time to move on,
remembering what caused this board failure so as not to make the same
mistake twice.

Q

Quaoar wrote:
>
> You are on the proverbial fool's mission. There is 100% probability
> that there is other hidden damage to the board. Time to move on,
> remembering what caused this board failure so as not to make the same
> mistake twice.
>
> Q

I know. I don't like Asrock either. I would rather like to play with it
"in the name of science". And of course - You are probably right, there
is a very high chance that something more has been damaged. But since
the MB is being replaced tomorrow - I can play with it for a while
before trashing it

--
Best regards,
Darek

In article <dn2k7p$kon$(E-Mail Removed)>, Darek <(E-Mail Removed)> wrote:

> Quaoar wrote:
> >
> > You are on the proverbial fool's mission. There is 100% probability
> > that there is other hidden damage to the board. Time to move on,
> > remembering what caused this board failure so as not to make the same
> > mistake twice.
> >
> > Q
>
> I know. I don't like Asrock either. I would rather like to play with it
> "in the name of science". And of course - You are probably right, there
> is a very high chance that something more has been damaged. But since
> the MB is being replaced tomorrow - I can play with it for a while
> before trashing it

If you are getting an exact replacement for the board tomorrow,
copy the numbers off the top of the chip, on the new board. Then post
them tomorrow and we'll tell you what it is, if possible. If there
is a logo printed on the chip, that helps too -- either sketch
the logo or describe it.

The best picture of the motherboard is on the Asrock site, but it
isn't good enough to get a part number. I don't see a logo, and
only two rows of numbers/letters. One row has four characters,
and that is likely the date code (WWYY) like 0305.

Paul

Paul wrote:
>
> If you are getting an exact replacement for the board tomorrow,
> copy the numbers off the top of the chip, on the new board. Then post
> them tomorrow and we'll tell you what it is, if possible. If there
> is a logo printed on the chip, that helps too -- either sketch
> the logo or describe it.
>
> The best picture of the motherboard is on the Asrock site, but it
> isn't good enough to get a part number. I don't see a logo, and
> only two rows of numbers/letters. One row has four characters,
> and that is likely the date code (WWYY) like 0305.
>
> Paul

That's the problem. Like I already said - Asrock isn't my favorite
brand, so I will replace it with Asus, Abit, Gigabyte or so. This is the
reason why I am looking for someone, who has this mobo.

I was able to read from the damaged chip the last digit - it's 8. The
one earlier could be 5 (so this could be LM358, but I am not sure about
that). I will wait a little more, maybe someone could confirm this.

--
Best regards,
Darek

On Tue, 06 Dec 2005 12:19:13 +0100, Darek <(E-Mail Removed)>
wrote:


>That's the problem. Like I already said - Asrock isn't my favorite
>brand, so I will replace it with Asus, Abit, Gigabyte or so. This is the
>reason why I am looking for someone, who has this mobo.
>
>I was able to read from the damaged chip the last digit - it's 8. The
>one earlier could be 5 (so this could be LM358, but I am not sure about
>that). I will wait a little more, maybe someone could confirm this.


I suspect it is an LM358, but I don't know it for certain.

Since that is the supply for the memory, you might want to
leave the memory out of the motherboard for testing
purposes, until you measure the voltage and confirm it in
the expected (~ 2.5-2.8V) range.

In article <dn3s3f$1lj$(E-Mail Removed)>, Darek <(E-Mail Removed)> wrote:

> Paul wrote:
> >
> > If you are getting an exact replacement for the board tomorrow,
> > copy the numbers off the top of the chip, on the new board. Then post
> > them tomorrow and we'll tell you what it is, if possible. If there
> > is a logo printed on the chip, that helps too -- either sketch
> > the logo or describe it.
> >
> > The best picture of the motherboard is on the Asrock site, but it
> > isn't good enough to get a part number. I don't see a logo, and
> > only two rows of numbers/letters. One row has four characters,
> > and that is likely the date code (WWYY) like 0305.
> >
> > Paul
>
> That's the problem. Like I already said - Asrock isn't my favorite
> brand, so I will replace it with Asus, Abit, Gigabyte or so. This is the
> reason why I am looking for someone, who has this mobo.
>
> I was able to read from the damaged chip the last digit - it's 8. The
> one earlier could be 5 (so this could be LM358, but I am not sure about
> that). I will wait a little more, maybe someone could confirm this.

I had a look at the LM358 datasheet (national.com), and while it
has a current limit on it, it has no thermal protection.

"Note 2: Short circuits from the output to V+ can cause excessive
heating and eventual destruction. When considering short cirucits
to ground, the maximum output current is approximately 40 mA
independent of the magnitude of V+. At values of supply voltage
in excess of +15V, continuous short-circuits can exceed the power
dissipation ratings and cause eventual destruction. Destructive
dissipation can result from simultaneous shorts on all amplifiers."

Did you plug in a DIMM backwards or something ?

In any case, if you ever find a clear enough picture of the board,
and the cause of the short circuit is removed from the board,
check with an ohmmeter on pin 1 or pin 7, to see if the
chip is still shorted to something like a power supply rail.
There could be some other component that is damaged as well,
as it is unlikely the opamp drives the load directly. Like a
failed MOSFET or something.

If you did reverse a DIMM, or partially install a DIMM (not fully
seated), there could be other damages you cannot see.

Paul

Paul wrote:
>
>
> Did you plug in a DIMM backwards or something ?
No I'm not that strong Besides this is not my mobo. But the owner
of this board could do anything to it, so this is the possible case.

>
> In any case, if you ever find a clear enough picture of the board,
> and the cause of the short circuit is removed from the board,
> check with an ohmmeter on pin 1 or pin 7, to see if the
> chip is still shorted to something like a power supply rail.
Pin 1 seems to be shorted to +3.3V rail. I've checked all the pins
versus all power rails and 0V. I was expecting GND (4) connected to 0V
or -5V or -12V, and +V (8) connected to either +3.3/+5/+12V or to the
output of one of the mosfets on board. But they are not. And no other
pins are.

> There could be some other component that is damaged as well,
> as it is unlikely the opamp drives the load directly. Like a
> failed MOSFET or something.
Probably. For now I just tested mosfets around this chip if they are
shorted, but mosfets seem to be ok.

>
> If you did reverse a DIMM, or partially install a DIMM (not fully
> seated), there could be other damages you cannot see.
>
> Paul
I just tried to replace the chip with LM358. It didn't blow up, it's
cold. But the mobo still refuses to wake up (both on DDRs and SDRs). So
either this is not the correct chip, or - like You said - there is
something more damaged. Bios beeps with a memory error code.

Anyway - thanks for help. I'll leave the board alone for some time now,
maybe someone will identify this chip on his/her mainboard and write
it... If not, this mb isn't worth too much trouble

--
Best regards,
Darek

In article <dn50hh$vrs$(E-Mail Removed)>, Darek <(E-Mail Removed)> wrote:

> Paul wrote:
> >
> >
> > Did you plug in a DIMM backwards or something ?
> No I'm not that strong Besides this is not my mobo. But the owner
> of this board could do anything to it, so this is the possible case.
>
> >
> > In any case, if you ever find a clear enough picture of the board,
> > and the cause of the short circuit is removed from the board,
> > check with an ohmmeter on pin 1 or pin 7, to see if the
> > chip is still shorted to something like a power supply rail.
> Pin 1 seems to be shorted to +3.3V rail. I've checked all the pins
> versus all power rails and 0V. I was expecting GND (4) connected to 0V
> or -5V or -12V, and +V (8) connected to either +3.3/+5/+12V or to the
> output of one of the mosfets on board. But they are not. And no other
> pins are.
>
> > There could be some other component that is damaged as well,
> > as it is unlikely the opamp drives the load directly. Like a
> > failed MOSFET or something.
> Probably. For now I just tested mosfets around this chip if they are
> shorted, but mosfets seem to be ok.
>
> >
> > If you did reverse a DIMM, or partially install a DIMM (not fully
> > seated), there could be other damages you cannot see.
> >
> > Paul
> I just tried to replace the chip with LM358. It didn't blow up, it's
> cold. But the mobo still refuses to wake up (both on DDRs and SDRs). So
> either this is not the correct chip, or - like You said - there is
> something more damaged. Bios beeps with a memory error code.
>
> Anyway - thanks for help. I'll leave the board alone for some time now,
> maybe someone will identify this chip on his/her mainboard and write
> it... If not, this mb isn't worth too much trouble

Hmm. Your measurements don't sound like a match for the LM358.

This is the best picture I could find. Maybe your eyesight is
better than mine.

http://www.asrock.com.tw/product/int...s/PEPRO-HT.jpg

When you pulled the chip, did the thickness and position of
copper tracks underneath the chip, suggest to you that the
chip is an opamp (low current device) or some other kind
of power device ? The copper in that area looks pretty big...

Paul

Paul wrote:
>
> Hmm. Your measurements don't sound like a match for the LM358.
>
> This is the best picture I could find. Maybe your eyesight is
> better than mine.
>
> http://www.asrock.com.tw/product/int...s/PEPRO-HT.jpg
>
> When you pulled the chip, did the thickness and position of
> copper tracks underneath the chip, suggest to you that the
> chip is an opamp (low current device) or some other kind
> of power device ? The copper in that area looks pretty big...
>

Just to finish the topic here is the conclusion

I guess this really is not LM358. Every integrated circuit on this
motherboard is marked as Uxx (xx is the number). And the transistors are
marked as Qxx. This little chip is marked as Q13, so it seems to be a
transistor, not the IC.

Tracks under the chip are thick (about 1mm wide), so this rather is a
medium power device.

I found some other Asrock mobos, they all seem to have such a chip
marked as Qxx. But on most of them it is a part marked as 4500M (and
googling for a while prooved, that this is a mosfet)

After some time of stairing at the large photo You gave me and searching
datasheets I think, that this chip may be a CEM942x or similar power
transistor.

Soldering as a replacement the 4500M gave me the desired effect - there
was about 2.55V voltage on a nearby mosfet, but the mobo still beeps
with a memory error (both on SDR and DDR).

Anyway it was fun to play - thank You all for Your time

--
Best regards,
Darek