way OT, laptop mobo schematics

i'm sure i've seen people post similar Q's on here before and been helped
out, so i may as well try my luck.

i've got an old-ish laptop, it let the magic smoke out one day after a loose
screw in the case shorted something out, it still worked but didnt accept
power, so when the battery dies that was it.

i got a new lappy and put the old un in a box and forgot about it, just
found it again so thought i'd see if i can get it going again, i only want
it to hook my multimeter to so i can use the recording and large display
thingies it does via a usb connection, and it'd be handy to use it for
running the vinyl cutting software i use, as that dosent take much
processing power up, and hence it'd be handy to have a lappy in the room i
have the cutter in rather than having to cart the one i use to surf for porn
in bed to the cutter everytime i want to cut some vinyl.

The laptop is a Acer Aspire 1350, model # MS2159... if that's any use,

the blown chip is an 8 pin surface mount, (U43 on the board) it's mounted
right after the DC input connector from the + terminal,
i can make out 4407 clearly, and then all i can see is 1H, the rest is
obliterated,


anyone know where i can find out what the IC is to replace it? i have tried
acer support, but they wont tell me, said send it in and they'll charge me
about the price of a new laptop to try and fix it,

i know i could get the lappy working by applying power to the battery input
terminals, but that'd be a faff as i expect it will want to see the correct
individual cell voltages on all the connectors rather than just a 14 volt
~DC input.

 

4407 is a MOSFET (simple search on google "4407 IC")

http://www.alldatasheet.com/datasheet-pdf/pdf/102778/ANACHIP/AF4407PS.html

If you have done something to make that make magic smoke then there will
probably be a domino effect on other stuff

 

If it's surface mount, forget it. Nige it out for spares or repair on
ebay and get on with your life ..

Paul.

 

While agreeing totally with wessie's comment, even I can change an 8
pin SMD.

As it's a case of 'nothing to lose by trying', either use *really*
fine cutters to snip the pins off individually or a scalpel to
carefully hack through them one at a time, in both cases right up
aginst the IC body , then gently sweep the stubs off with a soldering
iron.

You don't need the schematic to check that the input pins to the chip
are geting the right voltages, only the chip pin-out.

A touch of solder to tin the pads first, or a dash of flux may help.
Afterwards, if you've got any solder braid, use that to clean the
pads, otherwise, lightly tin them so they're all even and shiny then
tack a new chip down.

This may or may not work, but as I said, you've nothing to lose except
a little time and patience and one replacement chip.

Personally, I wouldn't bother but then, useful as they are, I hate
PCs.

 

****** *That*

And I have worked with SMD stuff in the past.

Well, once you've butchered the motherboard it's worth **** all on
Ebay, so you might as well punt it there than throw it in the bin.

Pretty much my sentiment

Me, I love 'em.

Bread and butter y'see ....

Paul.

 

it's a piece of piss - just flood the legs of the IC with solder, when both
sides of the IC are sitting in liquid solder lift off the device. Most of
the solder comes away and any crud on the pads. Quicker than using the
proper reflow hot air toys we had.

Unlikely to work. The heat from the burning MOSFET has probably damaged the
pads & base layers in a terminal fashion. Laptop mobos are made of cheese,
Kraft slice cheese. Then there's the other devices...

<ding>

 

Hmm. Used to do the for through-hole devices and it did work, however,
whenever I've tried that on modern PCBs, the sheer heatsink effect of
power or ground vias has prevented the solder from flowing enough for
it to work before the pads lifted. Still, I haven't tried it on cheapu
mobo's. I really, really hate PCs. They're disposable consumer goods.

Well, as long as the tracks or vias are still attached, not a problem.

 

I got me one of those.

 

'Real men don't use braid' eh?

I can recall having my own solder sucker at work, the PTFE tip trimmed
just so; the pin and barrel kept clean to minimise friction; the
piston face spotless to minimize inertia and the foam washer carefully
scrubbed and even lightly trimmed to prevent undue drag, for maximum
suck.

Tuned, you know, tuned to perfection.

[I was going to try for a hot-rod gag involving soldering irons but
ICBA to think]

 

Broken ?

We wear them out in a couple of months

 

Braid!! Braid is for poofs and other wimmin of a nervous disposition. A
**** that, i use me desolder / solder station thingy i got for xmas, i set
the heat to low-ish, gently wigglesd the nozzle on the pins, pressed the
trigger and 'brrrrrr sluuuurp' and the solder is gone.

the tip on the soldering iron is just small enough for the IC in question to
enable me to have a fairly good chance at splodging some solder down in the
right places to attatch a new un,

i am quite expecting the new ic to blow again, there's deffo signs that the
loose screw in the case touched the ic in question, not something further
down the line.

and i always have the option of powering it via the battery input
terminals, but it'd be easier if i could use the psu plugged into the
charge/power socket than faff about with hacking cables to the mobo to power
it via a psu thru the battery input.

btw, i found the 4407 ic's, but there are a fair few options for them, i
figured the other number on the chip would have told me which particular
flavour of 4407 i need,

 

<sniff>

Some of us didn't have to undo our work that much.

 

Given that the device is a MOSFET and 3 pins are connected together
for source and all four on the other side connect to drain, I don't think
the soldering is going to be very critical, except for that one gate pin.

--
Ivan Reid, School of Engineering & Design, _____________ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

this 4407 mosfet jobbie,

anyone know where i can buy one from? seems AF4407P or AN4407P are the most
common ones, the first letters are just the manufacturers name code anyway,

but i'm stuck finding where to get one, tried RS components, farnel,
maplins,

unfortunately that's my lot of component places i know of.... or ones that
will sell a small quantity, i know i'll prolly have to buy 5 for min order,

i found some on ebay but they are in portugal, so i'd rather keep that as a
last chance, as i'd like to get this damn thing asap, or i'm going to loose
bits to the laptop, i did have the screws all lined up as they came out of
their holes, but that's gone to pot in one swift hand movement when i needed
room on the bench.