how do printed circuits break?
 

As strange as it may sound, I have a similar problem with my cell phone and
my laptop. I tried to trouble-shoot and isolate the problem(s). Here's what
I found: bending the printed circuits a bit switches the devices from
working to non-working modes, but wiggling any connectors or wires has no
effect. So I'm assuming the problems are with the printed circuits
(mainboard in the laptop).

I can not see any bad contacts or other problems with the naked eye. What is
the most likely cause of such twilight (between working and broken)
symptoms in printed circuits?

Physically broken/cracked surface mount components or the solder
connections to same. Rarely visible to the naked eye.

"alex goldman" wrote in message
...
wrote:

Physically broken/cracked surface mount components or the solder
connections to same. Rarely visible to the naked eye.

Is it practical to try to diagnose it further, and if so, how?

I won't bother with the phone (it's cheap), but for the laptop I couldn't
locate a replacement motherboard, and getting a completely new one is
expensive.

Is it possible to fix a motherboard if it has such problems somewhere
(broken/cracked surface mount components or the solder connections to
same)? If so, what kind of equipment, knowledge and time commitment will I
need?

It can be done, you just have to narrow down the fault to as small an area
as possible and resolder everything. I've seen this sort of problem a lot of
times with vias that go from one side of the board to the other, expansion
and flexing breaks the plating between the layers and you get an
intermittant connection with nothing visible.

"alex goldman" schreef in bericht
...
wrote:

Physically broken/cracked surface mount components or the solder
connections to same. Rarely visible to the naked eye.

Is it practical to try to diagnose it further, and if so, how?

I won't bother with the phone (it's cheap), but for the laptop I couldn't
locate a replacement motherboard, and getting a completely new one is
expensive.

Is it possible to fix a motherboard if it has such problems somewhere
(broken/cracked surface mount components or the solder connections to
same)? If so, what kind of equipment, knowledge and time commitment will I
need?

In the days that PCBs were expensive, so you could take an hour or more to
pinpoint the fault, our techs used an hair dryer and a can of coolant. Of
course, experience was the other half of the requirements. The latter faded
away when the repairtime/board shrinked. I still own a working XT of which
the motherboard was rejected as the fault could not be located within half
an hour. I got it for a small contribution and made a running machine in one
evening. These days PCB repairs are rare, very rare. That's to say for
professional/commercial use. Even boardswapping becomes too expensive in
some cases. It has been six years now I bought a monitor. Within warranty
time it was swapped as a whole. After three years, when warranty was over,
it was said to be unrepairable and I was advised to buy a new one. To make a
long story even longer: Cans of coolant are still available but I'd use a
hot air soldering "iron" for the hot part. Components became very small you
know. Besides, you'll need lots of time and even more lots of luck.
Nevertheless it may be worthwile to give it a try. Good luck.

petrus bitbyter

try to check this link,
http://www.tpub.com/electronics.htm
i think this one might help you out!... dont worry, its free
download!...but if you can afford to buy it, im suggesting it!.. but
its up to you, of course!...:D , just try to check it!.. i hope you
like it!..




alex goldman wrote:
As strange as it may sound, I have a similar problem with my cell phone and
my laptop. I tried to trouble-shoot and isolate the problem(s). Here's what
I found: bending the printed circuits a bit switches the devices from
working to non-working modes, but wiggling any connectors or wires has no
effect. So I'm assuming the problems are with the printed circuits
(mainboard in the laptop).

I can not see any bad contacts or other problems with the naked eye. What is
the most likely cause of such twilight (between working and broken)
symptoms in printed circuits?

On Sun, 03 Jul 2005 22:15:49 -0700, alex goldman wrote:
As strange as it may sound, I have a similar problem with my cell phone and
my laptop. I tried to trouble-shoot and isolate the problem(s). Here's what
I found: bending the printed circuits a bit switches the devices from
working to non-working modes, but wiggling any connectors or wires has no
effect. So I'm assuming the problems are with the printed circuits
(mainboard in the laptop).

I can not see any bad contacts or other problems with the naked eye. What is
the most likely cause of such twilight (between working and broken)
symptoms in printed circuits?

Cold solder joint(s). Sometimes undectable to the eye even with
the use of a lens.

Using your "bending" technique to locate the suspect region of board.
Then, use a thin plastic 'probe' to poke at individual solder joints
until you find it -- or, at least better localize where the problem
exists. Then, re-flow solder all the joints in the area.

Google on "cold solder joint" -- _using the quotes in the search arg_

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
Pueblo, Colorado | @ | Jonesy | OS/2 __
| config.com | DM78rf | SK

petrus bitbyter wrote:

In the days that PCBs were expensive, so you could take an hour or more to
pinpoint the fault, our techs used an hair dryer and a can of coolant.

I don't think I understand: what did they use a hair dryer for? If it were
hot enough for melting solder, its manufacturer would probably get in
trouble with the intended customers.

Of
course, experience was the other half of the requirements. The latter
faded away when the repairtime/board shrinked. I still own a working XT of
which the motherboard was rejected as the fault could not be located
within half an hour. I got it for a small contribution and made a running
machine in one evening. These days PCB repairs are rare, very rare. That's
to say for professional/commercial use. Even boardswapping becomes too
expensive in some cases. It has been six years now I bought a monitor.
Within warranty time it was swapped as a whole. After three years, when
warranty was over, it was said to be unrepairable and I was advised to buy
a new one. To make a long story even longer: Cans of coolant are still
available but I'd use a hot air soldering "iron" for the hot part.

I didn't know these things existed. How can hot air (plasma?) be more
localized than a thin metal stick?

Regardless, I wouldn't want to spend $500-2000 on something that won't help
me localize the problem anyway.

Components became very small you know. Besides, you'll need lots of time
and even more lots of luck. Nevertheless it may be worthwile to give it a
try. Good luck.

"alex goldman" skrev i en meddelelse
...
wrote:

Physically broken/cracked surface mount components or the solder
connections to same. Rarely visible to the naked eye.

Is it practical to try to diagnose it further, and if so, how?

Microscope - and maybe x-ray the board. I would only do it if it was my
prototype coming back from testing ...

Is it possible to fix a motherboard if it has such problems somewhere
(broken/cracked surface mount components or the solder connections to
same)?

Hardly Ever - Only *If* it is someting trivial like a component visibly
cracked or fallen off or *maybe* a pin on an IC not soldered in properly.
Often it will be a broken via inside the PCB or a joint underneath a 480 pin
BGA, in which case you need the x-ray machine.

If so, what kind of equipment, knowledge and time commitment will I
need?

Ebay for "SMD" rework equipment. In general it will be cheaper to buy new
than the salary you would have to pay yourself.

Frithiof Andreas Jensen wrote:


Hardly Ever - Only If it is someting trivial like a component visibly
cracked or fallen off or maybe a pin on an IC not soldered in properly.
Often it will be a broken via inside the PCB or a joint underneath a 480
pin BGA, in which case you need the x-ray machine.

I suspect it's either the chipset or the GPU (both soldered directly onto
the mainboard). Before spending $1000+ on a new laptop, I think I'll try
heating the pins with a regular soldering iron (25 Watts) in the hope that
the flaws, if any, will heal themselves. Is this a good idea?

Nope, not a good idea. You need to properly apply a thin coating of
the correct flux over the pins after making sure the area is clean.
You also need a proper temperature controlled soldering station for the
type of solder that is going to be used. I typically use a silver
based solder for this type of rework as it flows smoother with less
beading up.

The more common problem on laptop boards is the via will become
dislodged and there is no real way to fix it without very expensive
equipment. These are multi-layer up to 16 circuit boards and you have
no access to the internal layers.

It does not hurt to do a good full visual inspection of the components
you do have access under a well lit 40X magnifier while moving the
board. With experience you learn what to look for on the board.

"alex goldman" ha scritto nel messaggio
...
petrus bitbyter wrote:

In the days that PCBs were expensive, so you could take an hour or more
to
pinpoint the fault, our techs used an hair dryer and a can of coolant.

I don't think I understand: what did they use a hair dryer for? If it were
hot enough for melting solder, its manufacturer would probably get in
trouble with the intended customers.

An hairdryer usually didn't have go too high, for melting solder there's
needed 300°, if an hayrdryer can go to 300°, probably we didn't have hair
anymore ;-)

I.

alex goldman wrote:

Frithiof Andreas Jensen wrote:


Hardly Ever - Only If it is someting trivial like a component visibly
cracked or fallen off or maybe a pin on an IC not soldered in properly.
Often it will be a broken via inside the PCB or a joint underneath a 480
pin BGA, in which case you need the x-ray machine.

I suspect it's either the chipset or the GPU (both soldered directly onto
the mainboard). Before spending $1000+ on a new laptop, I think I'll try
heating the pins with a regular soldering iron (25 Watts) in the hope that
the flaws, if any, will heal themselves. Is this a good idea?

Hello?

I plan to open up my laptop again - I need to know which end to stick the
hair dryer in :-)

"alex goldman" skrev i en meddelelse
...

I plan to open up my laptop again - I need to know which end to stick the
hair dryer in :-)

Forget it already. It's unfixable. The problem is now componded by you have
messing around with it so everyone will see the tampering and refuse to do
anything with it!!

Leave it on the front seat of your locked(!) car - or ship it as luggage
while travelling - then have the insurance pay for a new one ;-p