Adam said:
Thanks (Guru John), I bought the printer used from a shop.
The JetDirect card came with the printer.
At first, I assumed that it was a JetDirect 610N because
the driver CD's JetDirect Manual (hpjdagen.pdf) is for 610N.
But, the Configuration Page that came with the printer says
that it's a J6057A (or 615N), which I now believe it to be.
And, will be able to confirm this when the JetDirect card is removed.
Hmmm ... I'm not sure what exactly "propped up on 4 screws" means.
Is there a photo? I don't want to mess up.
To me, it looks like the guilty chip could be the square one.
I can't tell from the picture, whether that chip is BGA or
a pin grid array, but my guess based on symptoms, is the
chip is a BGA or ball grid array (as they respond to this
kind of reheating repair).
http://www.pacificgeek.com/productimages/xl/WPRLN003.jpg
What happens in some cases, is there is mechanical stress on
the corner ball grid array solder joints, and a ball can crack.
Heating the chip up, can "reflow solder" the ball again,
re-forming a proper connection.
You would have to be careful, as making the solder under that
chip molten, would also cause adjacent components and their
solder to melt as well. If you bump any of the other
components, while the card is hot, it could knock a
component off.
They make rework stations, which may have a heating mechanism that
heats an area on the bottom of the printed circuit board (underneath
the ball grid array chip), while the hot air device and shaped hood,
fits over the top of the chip. The device may even include an
automated temperature profile (soak and reflow), to reduce
stress on the workpiece.
http://www.zeph.com/bgarework_stations_systems_qfn_smd_hot_air_repair.htm
When you use your own hot air gun, oven or other heating solution,
you're duplicating what a professional device like that does,
only without the benefit of controlled temperature profile, clamping,
and both-sides-heating. A hot air gun doesn't have any heat control
and you don't know how hot you're getting the chip. Crude rework
machines, may include a thermocouple for monitoring workpiece
temperature.
Now, that rework machine, also includes a vacuum wand for picking up
the chip. So you can heat the chip, and a sucker placed against
the chip lid is used to lift the hot chip right off the board.
That is for cases where the chip needs to be replaced. Your
problem would be simpler, in that you're reheating the solder
underneath the chip, and reflowing a connection that is cracked
or no longer making connections.
The notion of "lifting the board with four screws" is using
screws as a mechanical support. The PCB may have some manufacturing
holes on it, and you may be able to elevate the board that way,
using the screws as standoffs.
People who use ovens for this (like a toaster oven),
generally use a "disposable" oven, an oven they won't be using
for cooking food. Heating an assembly like that, is likely
to burn the plastic. You'd at least try to remove any removable
plastic bits first, before doing the repair. By using a
toaster oven out of doors, you might even avoid stinking
up the premises.
A hot air gun, would control to some extent what part of
the PCB and components get hot, but without a shaped hood
to fit the part, you're still going to get adjacent parts
hot. On our hot air rework station at work, we had a drawer
full of various hoods, sized for particular chip sizes, so
you'd use just the right one for the job. But I never got
to use the machine, and there was one guy who was good at
using it, that did any repairs of that type. I didn't
even stick around to watch.
http://www.aoyue.com/en/UploadFiles/2006816114422225.jpg
Paul