I have to take a close look at length. I think it can work but with
changes.
On Saturday, August 10, 2019, Brian K. White <[email protected]
<mailto:[email protected]>> wrote:
Here is a messy pdf
http://tandy.wiki/images/c/c7/Pcb2molex8878_pcb_dims.pdf
<http://tandy.wiki/images/c/c7/Pcb2molex8878_pcb_dims.pdf>
If you are using the extreme corners, then maybe those notches
just have to go.
I could put a single notch in the middle instead. Or offset from
center so that it does double duty, polarization and trapping.
Or the locating and polarizing could be done some other way like
matching up pockets with some pcb components?
If a component poked down into a pocket, that would keep the pcb
located inside the carrier.
This shows the current version with little steps at the corners,
and allowing for the 0.034" mill radius, so the actual corners
where the arc made by the edge contact via intersects with the
router path is slightly different in reality than it looks in the
drawing. The mill radius ends up leaving the corner edge contacts
just barely untouched, while in the drawing it looks like the 4
corner contacts are cut down a little. I'm liking the idea of
simplifying the pcb shape to just be chamfers, and changing the
carrier to match. Simpler and just as functional. I may do that.
That pin is a tad larger than necessary too. I was worried about
it being too small for reliable 3d printing and having it be weak
and break off, so I increased it before I had even received the
first prints of the earlier version. Then the original version
turned out to be fine. I could still change it back I guess. (for
the generic carrier I mean, yours sounds like it will have to be
it's own thing or just not exist)
I could mail you a couple of the current version carriers so you
could get a feel for it and maybe carve one up a little and help
visualize what might be possible if something was changed a little
here or there.
One dimension that I think can't change much, which might be a
problem if you are really filling up the pcb, is the overall length.
You are surely working on a pcb that fills the socket, while to
fit in a carrier, it has to be a little bit shorter. There has to
be at least 0.7mm wall between the socket and the pcb.
I can imagine that it's not easy to make a change like that after
you already have a pcb stuffed with parts and traces.
--
bkw
On 8/10/19 1:29 PM, Stephen Adolph wrote:
Brian, some comments
I can see the benefit of pcb retention and support, as well as
installation ease. Bad springs are still bad springs .. not
much can be done there.
Dimensions would be super helpful thanks.
My original goal for all new designs was to have the major
parts on the same side to make manufacturing easier. As a
result there isn't space for the post.
Maybe one corner could be made diagonal as a way to show
orientation?
Like REX "classic" I have been planning to bring some signals
onto REXCPM in the extreme corners of the PCB. That approach
may not work now depending on space for the vias.
With all the large parts on one side.. it is actually a bit
hard to find places for vias for external signals.
On Saturday, August 10, 2019, Brian K. White
<[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>> wrote:
I'm getting some dims out of kicad now. Take me a few
minutes...
I think I'll add a layer for dims and print that.
The actual pcb doesn't have a chamfer at the corners, it has a
tiny step, but it's all so small, and the router radius is so
large, that in practical terms it might as well be a
chamfer. I
was just trying to give an idea for if you had an existing
original rex1 in you hands that you bought years ago, just
sanding
down the corners would be easy to do and should work.
And for working on a new design, it doesn't necessarily
have to be
that exact way. You just need some way to locate the pcb
in the
carrier. It could be some other notch or something instead of
those tiny vertical walls at the 4 corners. Those are just
left
over from the original carrier that held a dip chip. The pin
actually could handle one end, but I wouldn't want another
such
pin on the other end. Too much real-estate and then it
wouldn't be
as good at enforcing polarity. All in all, maybe
chamfering the
corners is the most practical way to trap the pcb after
all. For
that matter, I don't assume your current pcb even has
empty space
for the hole for that pin anyway. I was assuming you'd nip
it off
or I'd make a model that doesn't have it.
-- bkw
On 8/10/19 9:50 AM, Stephen Adolph wrote:
Update,
Took a close look at the latest. Looks great!
I like the retention clips that hold the PCB in place.
That
makes a lot of sense.
Looks like you have already opened up the space on the
carrier
for parts across the underside of the PCB-yes?
I dont use kicad; is there a board dimension you could
provide? ( is this written down somewhere?)0
Width 0.64 inch (oshpark)
Length 1.47 inch (oshpark)
Chamfer dimension ( done by hand?)
Reserved space for components on underside of PCB. IE
need to
know where chips, parts and leads can safely go.
Thanks.. Steve
On Saturday, August 10, 2019, Stephen Adolph
<[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>
<mailto:[email protected]
<mailto:[email protected]> <mailto:[email protected]
<mailto:[email protected]>>>>
wrote:
Brian,
I get that this carrier improves the look of the
install but I
dont see how it improves operation. It doesn't
improve
contacts
in my mind does it? I've done so many
installations of rex
now...I think the spacer and ribbon approach works
fine.
I agree
that I have a lot of practice though.
REXCPM has uses most of the secondary ie bottom
side for
parts.
Like REX2. So it won't work with this carrier.
Also the
flash
and cpld are placed right at the edge.
What is the board dimension you need? I will have to
reduce size
by the sounds of it and move parts. Not sure if I can,
depending.
It would mean pretty much every track re layed out.
Can you make a design that leaves pretty much all
of the
secondary
side available for TSOP48 and VQFP44? From what I
saw you
have a
cutout for the flash only, in the center.
Thx Steve
On Friday, August 9, 2019, Brian K. White
<[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>
<mailto:[email protected]
<mailto:[email protected]> <mailto:[email protected]
<mailto:[email protected]>>>>
wrote:
That modified rex pcb and matching carrier I was
working on
are now at a usable state.
There is a pcb which is REX1 electrically,
with only some
layout and edge cut changes.
There is another pcb with the same outline
that uses
the same
carrier, but has only a simple eeprom on it. I'm
calling that
Teeprom.
There is a github with both the carrier 3d
model and
an empty
template version of the matching pcb, to make
new circuits
using the same pcb and carrier. So hopefully
this is
reusable.
By now I have received and tested multiples of
both
pcbs and
the carrier, and everything is dialed-in
pretty well
finally.
I have several rex's and teeproms and a bunch of
carriers all
of the current/latest versions the same as what's
currently
orderable on oshpark and shapeways, and the
boards all fit
perfect in all the carriers, and the carriers
& boards
all fit
and work in my couple M100's, T102, and T200.
I overhauled the build and flash directions a lot.
Filled in
more deatails with actual steps as if going
from scratch,
expanded some steps into their own separate
docs but
linked
right where you need them. Could still do more but
it's just
better than before. Simplified and organized a
little
better
(I hope).
http://tandy.wiki/REX
http://tandy.wiki/Teeprom
http://tandy.wiki/Pcb2molex8878 <http://tandy.wiki/Pcb2molex8878>
<http://tandy.wiki/Pcb2molex8878
<http://tandy.wiki/Pcb2molex8878>>
<http://tandy.wiki/Pcb2molex8878
<http://tandy.wiki/Pcb2molex8878>
<http://tandy.wiki/Pcb2molex8878
<http://tandy.wiki/Pcb2molex8878>>>
http://shpws.me/RngB
https://github.com/aljex/pcb2molex8878
<https://github.com/aljex/pcb2molex8878>
<https://github.com/aljex/pcb2molex8878
<https://github.com/aljex/pcb2molex8878>>
<https://github.com/aljex/pcb2molex8878
<https://github.com/aljex/pcb2molex8878>
<https://github.com/aljex/pcb2molex8878
<https://github.com/aljex/pcb2molex8878>>>
https://photos.app.goo.gl/zynHU4LSpd5BZBYC9
<https://photos.app.goo.gl/zynHU4LSpd5BZBYC9>
<https://photos.app.goo.gl/zynHU4LSpd5BZBYC9
<https://photos.app.goo.gl/zynHU4LSpd5BZBYC9>>
<https://photos.app.goo.gl/zynHU4LSpd5BZBYC9
<https://photos.app.goo.gl/zynHU4LSpd5BZBYC9>
<https://photos.app.goo.gl/zynHU4LSpd5BZBYC9
<https://photos.app.goo.gl/zynHU4LSpd5BZBYC9>>>
I'll get the rex and teeprom full sources up in a
github or
something soon too. The .kicad_pcb files are
already
available
via oshpark, but you want the rest of the
kicad files
too if
you were going to work on them.
Anyway, it's at the point now where I'm saying
it's ok to
order these things and they'll work and I'm
not still
changing
them and obsoleting them right after you
ordered them.
Just for the record, I have the shapeway shop
set at
0% markup
for all the items. I don't want any damned
shop but that's
just the only way you can share the model on
shapeways
so that
other people can order prints without
downloading and
uploading the mesh files themselves. The same
model is
also on
thingiverse where you can share without having
a shop, but
thingiverse is mostly FDM printers, and I
don't think
any fdm
printers are good enough for this part. But,
if you
have your
own printer and want to try it, the mesh file
is up
there. So
the only reason there is a "shop" on shapeways
is just
to get
shapeways laser sintered nylon printing. It
comes out very
clean and accurate and strong enough that the
part is
actually
usable.
You may notice that the seemingly nicer print
options
are not
enabled for this on shapeways. That's on
purpose. If
you get
the part printed in multijet fusion, it looks
great, but
doesn't fit.
Unfortunately, for the carrier, my freecad
"source" file,
while available in the github, isn't actually very
"source"-like. It's essentially just the final 3d
solid shape
just like the stl file for printing, not all
the steps to
build it up, nor any parametrics you can edit.
But I
do plan
to redraw it from scratch in freecad or better yet
openscad
sometime. Especially openscad will make it
awesome for
keeping
in git.
Also if you wanted, it IS actually possible to
modify a
standard REX to go in one of these carriers.
You would do 4 things:
1: Cut the polarity pin off the carrier.
Doesn't have
to be
any more accurate than just lower than the lip
on the
bottom
tray. Just use wire cutters or a knife.
2: Sand both ends of the pcb (the two short
dimensions) down
about 0.5mm each, or whatever it takes until
the overall
length is 37.35mm or shorter, and doing both
ends equally.
This will eat into the jtag pin holes a
little, but
actually
not enough to hurt anything. You could even
still use
the jtag
port if you ever needed to. It doesn't affect
normal
operation
at all.
3: Chamfer all 4 corners of the pcb edge about
1mm each
corner. Make the very ends narrow enough to get
between the
vertical walls on the ends of the carrier, yet
don't
chew into
the edge contacts at pins 1, 15, 15, 28 more
than about
10-20%. You can actually graze the ends of
those 4 corner
contacts slightly and they'll still make
perfectly good
contact. But you should be able to just barely not
touch the
actual half-circle part.
4: Remove anything glued to the bottom of the pcb.
Some glue
residue left behind would be ok on the pcb surface
next to the
flash chip, up to the thickness of the flash
chip, but the
surface of the flash chip should have nothing
thicker than
paper on it.
-- bkw
On 7/29/19 9:34 AM, Josh Malone wrote:
Fred,
If this is one of my REX units (shipped
with wood
spacer
and a purple
polka-dot ribbon) then my apologies for
your issues. I
tested the
spacer sizing in 100, 102, and 200 units
and found
what
seemed like
the right size to prevent over-insertion and
"spontaneous
removal".
I'd have to check my notes, but I sanded
my boards
down to
a precise
size which I think was 0.048" (~1.2mm).
They do
require a
very firm
insertion into the socket -- you may feel
uncomfortable
applying that
much force -- but you should feel the
board snap into
place below the
catch in the pins. If you don't feel a
"snap" then
it is
possible that
the spacer board is too thick for whatever
reason.
I don't
use any
adhesive, etc. on my boards to make it
easier to
repair
them should
anything go wrong, but I've also had one other
issue with
a user
neglecting to install the spacer which caused
damage to
the REX and
his M100, so I will be changing to adhesive
spacers on my
next batch
(which I'm producing the Tandy Assembly).
When you install REX, do you feel it snap into
place? Can
you send
pictures of the installed REX? (You'll have to
find a host
for them
since the list doesn't handle attachments;
or send
them
directly to
me)
Brian's work with the new REX PCB and the
3D-printed
carrier looks
neat -- I'm following his progress -- so
if you
continue
to have fit
issues one of those carriers might solve your
problem, as
well.
https://photos.app.goo.gl/aNfjvB1XucSehPGB9
<https://photos.app.goo.gl/aNfjvB1XucSehPGB9>
<https://photos.app.goo.gl/aNfjvB1XucSehPGB9
<https://photos.app.goo.gl/aNfjvB1XucSehPGB9>>
<https://photos.app.goo.gl/aNfjvB1XucSehPGB9
<https://photos.app.goo.gl/aNfjvB1XucSehPGB9>
<https://photos.app.goo.gl/aNfjvB1XucSehPGB9
<https://photos.app.goo.gl/aNfjvB1XucSehPGB9>>>
-Josh
On Sat, Jul 27, 2019 at 8:29 PM Stephen Adolph
<[email protected]
<mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>> <mailto:[email protected]
<mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>>> wrote:
Hi Fred,
Honestly my first thought here is ... what
software
are you running and have you ever done
a total
wipe of
rex followed by a reload from scratch
of the
software?
These symptoms more or less sound like
corruption of
the directory which can happen on older
software loads.
I've tried to catch all the fixes in
my last
supported
software load. Which is at bitchin100.
..Steve
On Saturday, July 27, 2019, Fred Whitaker
<[email protected]
<mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>> <mailto:[email protected]
<mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>>>
wrote:
I have been having trouble with my
REX chip
becoming loose and losing data as a
result. The
computer also locks up. I was
wondering if
anyone
had any ideas about better support
for the
chip
corners, instead of a loose piece
of wood
under it.
I was thinking of trying to find
some small
diameter thin stick on feet, about 1/8
inch thick.
Has anyone had a similar problem?
The problem will be the same with
any of
the ROM's
on similar boards. The Super ROM
that I
have is on
a similar board but it also has a
full length
spacer glued to the bottom of the
board.
Until I can resolve this issue I am
putting my REX
chips in storage. This is only
true for
the Model
100 and Model 102.
