Isaac Wingfield wrote in message
...
In article ,
"Stellijer" wrote:

--snip--

How would you ever replace an IC on these boards? They look like you'd have
to solder them with microscoping equipment! Also, I would have no idea
where to
get that same IC or know WHICH is the motor driver IC.

Getting the IC may be a problem, but replacing it with "ordinary" tools
is only moderately difficult (assuming you can *see* the pins; if it's a
ball-grid job, you're out of luck):

1) With a sharp hobby knife, cut through all the legs of the bad chip,
right next to the body of the chip. Take care not to cut any traces on
the board. The body may have a bit of stuff on the bottom to attach it;
you may have to lever it up a bit to get it off. MAKE SURE you've cut
all the legs before you do this.

2) Using a "solder sucker", you can melt the solder and "suck" the
individual pins off the board. Work quickly. Make sure none just move
somewhere else and get overlooked.

3)If the pads still have "bumps" of solder, use some solder wick to
clean things. Clean the flux off with acetone. Put a little more solder
on two opposite corner pads.

4) Orient the replacement chip (you *did* notice which way the broken
one went, right?) and *making sure all the pins are directly above their
appropriate pads*, tack down those two corner pads.

5) Re-check to make sure that no leg is bridging adjacent pads.

6) Using fine solder, just run a small iron around the chip, covering
all pins with solder. Make sure every pin is attached to its pad. DO NOT
WORRY about solder bridges at this time.Working quickly is more
important.

7) Once again use the solder wick, this time to remove all solder
bridges. Use a loupe, if you have one.

8) After you're confident that all legs are attached and there are no
bridges, clean off any remaining flux with acetone.


Wow. It's actually interesting to know how to do this but still it seems
daunting, if you add to it the difficulty of obtaining the chip, too.

I imagine my best shot is to find another working PCB and replace the whole
thing. I only hope that the control chip (and thus the PCB) solve the
problem...