What is this laptop motherboard component?

[gk]

This is my first time posting, so I apologize ahead of time for any
breach in netiquette.

Can anyone please help me find out what this component is? It shorted
out (water spill) on a Dell Inspiron 5100 laptop motherboard. It is an
8-pin package and the markings are:

2042A
36T
DCFR

Picture here:
http://img219.imageshack.us/img219/3850/2042a3ku.jpg

Picture cleaned up:
http://img219.imageshack.us/img219/737/2042aclean7cz.jpg

Any ideas on where to find a replacement for the component?

Thanks,
gk

 

[Tony Marsillo]

GK,
You can get the data sheet here.

http://www.datasheetcatalog.com/datasheets_pdf/T/P/S/2/TPS2042A.shtml

 

[gk]

Thanks Tony,

So the part number I should be looking for is "TPS2042A"? And is it
fairly straight forward to solder? I'm by no means an expert. There's
probably other undiscovered damage to the motherboard that I might have
to worry about too...

Thanks again,
gk

 

[Dave Platt]

This is my first time posting, so I apologize ahead of time for any
breach in netiquette.

Can anyone please help me find out what this component is? It shorted
out (water spill) on a Dell Inspiron 5100 laptop motherboard. It is an
8-pin package and the markings are:

2042A
36T
DCFR

Texas Instruments logo. A wildcard search (*2042a*) at
www.datasheetarchive.com turns up the TI TPS2042A, described as
"0.7A, 2.7-5.5V Dual (1In/2Out) Hi-Side MOSFET, Fault Report, Act-Low
Enable." The data sheet for that part, downloaded via the link
provided, describes it as a "current-limited power distribution
switch" and shows that it does come in an 8-pin package which
resembles the one in your picture. So, I sorta figure that's what you
have there. Must have made a nice BANG when the leg came off :-(

This is apparently an obsolete part - none of the usual distributors
such as DigiKey or Mouser have any in stock, and (apparently) neither
does TI.

TI lists it as having been superceded by an "exact replacement", the
TPS2042B. Digi-Key has the TPS2042BDR in stock for $1.68 each.

That's likely your best bet, I think.

 

[[email protected]]

Followups set to sci.electronics.repair.

So the part number I should be looking for is "TPS2042A"?

I _think_ that is right. If so, TI's page for it at
http://focus.ti.com/docs/prod/folders/print/tps2042a.html
says it has been replaced by the TPS2042B. That page says it is
basically a power switch that can handle up to 0.5 A, which is a
relatively large current for inside a laptop. The fried pin looks like
the the input voltage to the chip, and the one immediately to its left
is ground. That looks like a good set-up for a short from the spilled
water.

Digi-Key sells the TPS2042BDR for about $2 each.
http://www.digikey.com/scripts/dksearch/dksus.dll?Detail?Ref=395069&Row=70309&Site=US
For orders below about $25 I think there is an additional handling
charge.

And is it fairly straight forward to solder?

I haven't had much experience soldering surface-mount components. You
need a soldering iron with a fine pointed tip, not big and stubby, and
having some small-diameter solder also helps. If you've got an old junk
network card or hard drive or something kicking around, you might
practice unsoldering and resoldering components on that before attacking
the laptop. http://www.repairfaq.org/REPAIR/F_tshoot.html#TSHOOT_029
has good information on soldering and desoldering.

Matt Roberds

 

[Stuart]

It's a Texas Inst. TPS2042A MOSFET fault report, act-low enable. DCFR=Dual
Cmos Fault Report. Datasheet at www.datasheetcatalog.com.

 

[Conor]

Thanks Tony,

So the part number I should be looking for is "TPS2042A"? And is it
fairly straight forward to solder?

Not in that state. You're going to have to do some major track
rebuilding. Not only that, if it's a 3 layer or more board, it might
not work as it could've eaten through another layer and you've no hope
in hell of tracing that.

Even if you do get it soldered, to do that much damage needs a hell of
alot of current and there's probably damage to other components too.

 

[Conor]

Texas Instruments logo. A wildcard search (*2042a*) at
www.datasheetarchive.com turns up the TI TPS2042A, described as
"0.7A, 2.7-5.5V Dual (1In/2Out) Hi-Side MOSFET,

Highly likely something else has been killed too then if it's a MOSFET
and there's that much damage.

 

[Dave D]

This is my first time posting, so I apologize ahead of time for any
breach in netiquette.

Can anyone please help me find out what this component is? It shorted
out (water spill) on a Dell Inspiron 5100 laptop motherboard. It is an
8-pin package and the markings are:

2042A
36T
DCFR

Picture here:
http://img219.imageshack.us/img219/3850/2042a3ku.jpg

Picture cleaned up:
http://img219.imageshack.us/img219/737/2042aclean7cz.jpg

Any ideas on where to find a replacement for the component?

Thanks,
gk

The pad is completely missing, leaving a thru-hole visible where the pad
used to be. You'll have to trace that thru hole and see which component it
leads to so you can link it with wire.

IMO, this is not a practical repair for anyone but the most experienced
engineer. It's almost certain that when the component shorted it took out
other semiconductors, possibly the regulator IC, chipset IC, maybe even the
CPU.

Your best bet might be finding the same model with a cracked LCD on eBay,
and swapping the LCDs over. However, even the same model laptops have been
known to use different LCDs.

Dave

 

[Mark D. Zacharias]

This is my first time posting, so I apologize ahead of time for any
breach in netiquette.

Can anyone please help me find out what this component is? It shorted
out (water spill) on a Dell Inspiron 5100 laptop motherboard. It is an
8-pin package and the markings are:

2042A
36T
DCFR

Picture here:
http://img219.imageshack.us/img219/3850/2042a3ku.jpg

Picture cleaned up:
http://img219.imageshack.us/img219/737/2042aclean7cz.jpg

Any ideas on where to find a replacement for the component?

Thanks,
gk

I would try just cleaning away the corrosion first. You might get lucky.

Mark Z.

 

[Dave D]

I would try just cleaning away the corrosion first. You might get lucky.

Mark Z.

You might want to take a closer look at the second picture ;-)

Dave

 

[Woody]

http://focus.ti.com/lit/ds/slvs247/slvs247.pdf

 

[Al]

http://focus.ti.com/lit/ds/slvs247/slvs247.pdf

I'm afraid you are cooked! It looks like the pad for the part is gone
also. If there was an electrical short afterwards which fused the
metallization, it may have caused damage to the metallization runs
underneath. At any rate, it may be impossible to make connection to that
one pin unless you know exactly where it goes and can put in a jumper.

Al

 

[Franc Zabkar]

The pad is completely missing, leaving a thru-hole visible where the pad
used to be. You'll have to trace that thru hole and see which component it
leads to so you can link it with wire.

IMO, this is not a practical repair for anyone but the most experienced
engineer. It's almost certain that when the component shorted it took out
other semiconductors, possibly the regulator IC, chipset IC, maybe even the
CPU.

I'd remove the IC and check the voltage on the input pad (after you've
repaired it). I'd also check for shorts on the output pins (6 & 7). It
may be that one of the IC's internal MOSFETs failed catastrophically.

Your best bet might be finding the same model with a cracked LCD on eBay,
and swapping the LCDs over. However, even the same model laptops have been
known to use different LCDs.

Dave

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.