Thanks for the info on the motherboard fix. Now when my serial port dies
I will know what chip to replace. Sounds like an easy $200 savings.


Regarding IC replacment, you definitely have a good idea to keep the
iron wattage down. I would recommend something in the 15-30 watt range.
My favorite technique is to use a solder sucker (one of those spring
loaded tools) and remove the iron right before I actuate the solder
sucker. If all the solder is not removed, then I add fresh solder and
try again. After all the solder is removed on all the holes, I test to
see if the chip will come out. If not, I take small needle nose pliers
and GENTLY wiggle each one of the 14-16 leads. You should not have to
exert much pressure at all, you should just be breaking loose small
threads of solder. If a SMALL mount of wiggling back/forth does not free
it, you need to remove more solder.

Here is another less risky procedure for those not comfortable with the
above. Take a sharp pair of cutters and cut the leads of the bad chip
right off at the plastic body. With the body of the part out of the way,
trim the leads about halfway down. Take the new part and sandwich it in
between the two sets of leads. The leads coming from the motherboard
should extend about halfway up the leads of the new part. Solder the
leads together. Note: This method does not look as pretty and the new
part sits up much higher, so make sure there is no height restrictions.
It would not be considered a professional fix, but would be adequate for
most applications and minimizes the possibility of damaging the barrel
of the via. Pay close attention to the polarity.

Just FYI,

Bill Campbell


________________________________________
Bill Campbell
Module Product Engineering
Fast Static RAM Division
Motorola Networking & Computing Systems Group
Austin, Tx.
________________________________________
------------------------------------------------------------------------




> so it looks like U9 was, indeed the culprit.
>
> Take care if you intend to try a chip replacement yourself. The
> motherboard is a high quality, multi-layer glass phenolic board with
> very small, delicate etchings. Replacing U9 would require a reduced
> heat iron to insure that the etchings would survive the process.
>

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