29 Dec
1998
29 Dec
'98
1:25 a.m.
*The broad traces are wrinkled and bubbled, light green in colour and
*coating is easily comes off.
Yup. And that coating burns easily, too.
*That transformer is under the floppy, and is about tad under 25"
*cubic size. Saw them in few III's. Those III's are very popular in
*high school they're by bunches.
Woah! a 25 cubic inch transformer! I hope that's a typo. It wouldn't even
fit in the case. Must be some special model of III. The only thing that's
under the floppies on mine (or any others that I've ever seen) is the ribbon
cable from the keyboard.
--
-Jason Willgruber
(roblwill(a)usaor.net)
ICQ#: 1730318
<http://members.tripod.com/general_1>
29 Dec
29 Dec
12:31 p.m.
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6:07 p.m.
New subject: Trivia for the Day
Tony Duell wrote:
Certainly on some PCBs (no idea if Tandy boards do this), the current
flowing in some tracks (power and ground) gets them hot enought to make
the coating wrinkle up a bit. Some boards do this even in normal
operation (!).
The solder mask wrinkle is caused by the solder plated traces getting hot
enough to melt the solder. The result is a wrinkled solder mask. Almost
all boards I have seen with solder mask applied over reflowed solder,
stuffed with components, and then run through a wave soldering machine will
show the same thing.
Trivia for the day - One of the reasons the SMOBC (Solder Mask Over Bare
Copper) process was developed was the cost of wave soldering. I have seen
boards that were solder masked over reflowed solder that have picked up as
much as 1 pound of solder when run through the wave soldering machine (the
solder accumulates under the solder mask.) This tends to drive up the cost
of wave soldering the boards :)! SMOBC boards also do not wrinkle the
soldermask when run through the wave soldering machine.
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ard＠p850ug1.demon.co.uk -
marvin＠rain.org -
roblwill＠usaor.net