Hi!
> On Mon, 17 Nov 1997, Allison J Parent wrote:
>
Snip
> > Surface mount offers compact and also better signal integrity for ultrafast
> > logic. There are many good reasons for surface mount that are in the realm
> > of quality improvement. Yes, it's take more skill to fix and some of the
>
> IMHO, surface mount repairs are not that hard given the right tools - a
> temperature-controlled soldering iron with a fine tip, fine silver-loaded
> solder and a steady hand will suffice for most repairs. You don't _need_ a
> hot-air rework station - such a unit will make the repairs faster, sure,
> but not necessarily any better.
Successfully done on that fine pitch gull leads with a common tiny
fine spring shaped to small L hook and heat each pin, pull on that
wire to flick some solder out and seperate that leads. Done that on
386sx chips and many IDE chipsets because they blow up and one I/O
chip on a recent P5 asus. (!) For J leaded types, I just melt too
much solder and lead that blob for fixing bad solder joints or
soldering in. To remove this I do not know unless you have hot air.
> Don't try to remove the old component in one piece. Cut off the pins
> (_carefully_), remove the 'body' and desolder the pins one at a time. Mind
> you, I tend not to remove pin-through-hole devices in one piece unless I
> know the device is rare and/or I am removing it to dump the contents. When
> I repair something, suspect TTL devices get removed one pin at a time -
> OK, so I may be replacing a few pounds worth of chips that were OK, but at
> least the PCB will survive.
If it's rare part, save it unless you're SURE it's totally blown by
funny behavior or cracked or smelly and bubbled. For common TTL IC's
I just snip 'em to save time and wear n tear on PCB. I do that same
to DRAM's.
> > parts are not easy to come by.
Do it from scrap boards for good oddball parts?!
> >
> > FYI in the industry there a few descriptions of part of the problem.
> >
> > Good, fast, cheap, pick two.
> > Cost of repair exceeds value of unit. Fix/trash decision.
>
> What is a problem is when it was decided at the time of manufacture that
> it was cheaper to replace than repair, so service manuals were never
> available. Now, 10 years on, there may be no chance of finding a
> replacement, so you have to repair. And repairing something without docs
> is the second-worst job that I know (the worst is repairing something
> with an incorrect/incomplete manual!)
True that why I'm worried and maddening.
> Case in point : Zip drives. I won't use one because no service manual or
> bit-level description of the disk is available. At some time in the future
> all the drives will have died. And then there's no chance of ever reading
> a zip disk again.
Then we use number to PRESS on Iomega to make it popular item and
provide specs or crack 'em the secrets. :) That technology is very
desiresble because those disks is so inexpensive and very durable
even the drives breaks. I can't stand thinking about LS-120!
Even we can tell them to improve on one problem because I already
ID'ed a problem that are killing those drives jarring those heads
when 4 pins hits home at ejection, Using floppy type ejection design
is better because it does not move the heads and use the fiction to
soften up the eject speed. Don't worry about the head, it retracts
completely out of the disk automatically.
This is what I like about the Zip IDE drives it's a right design like
the floppy drive machism. But I wished Iomega sell one in SCSI
version as well which means we have to press for it!
Troll
>
> > Allison
>
> -tony
Received on Mon Nov 17 1997 - 09:42:48 GMT
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