1 Oct
2015
1 Oct
'15
10:58 p.m.
"My guess would be cost. Those headers back then were somewhat expensive
due to the heavy (30) gold plating."
Wow. I never even considered that a header could be more costly than a
74LSXXX chip - doesn't make sense. But then again, I wasn't in the field
back in that day.
On Thu, Oct 1, 2015 at 10:48 PM, Tothwolf <tothwolf at concentric.net> wrote:
On Thu, 1 Oct 2015, drlegendre . wrote:
Also, I'm curious about the 50-pin headers.. why were they never
installed? All of the other work was done, all
the expensive parts (chips)
are in-place - so why not a couple of cheap headers? Yes, a few resistor
SIPs are gone, as is one chip missing, but still, you get the point.
My guess would be cost. Those headers back then were somewhat expensive
due to the heavy (30) gold plating.
I found out today that as of August 3M has discontinued their 3000 series
gray box headers and the last time buy on them was October 1st. They are
replacing them with the D3000 series made with black fiberglass reinforced
nylon instead of the gray nylon they've always used. (3000 series datasheet
attached)
The part numbers for the 50-pin headers without eject levers for 1/16"
thick pc board would be 3433-5002. Mouser shows some stock, however their
system may or may not be correct and they might try to substitute the newer
D3000 series.
http://www.mouser.com/ProductDetail/3M/3433-5002/?qs=%2fha2pyFadugF4%2fyP%2…
I also spotted some 3433-5402 on eBay at a reasonable price that might
work, however those use a roll pin to attach the eject levers, so they are
much harder to remove than the ones that used snap-in eject levers.
http://www.ebay.com/itm/3M-3433-Locking-Ejector-Header-50-pin-right-angle-g…
Also, don't forget about C2. It and C1 were probably a matched set for the
crystal.