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]>> 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]>> 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://shpws.me/RngB
https://github.com/aljex/pcb2molex8878
<https://github.com/aljex/pcb2molex8878>
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>
-Josh
On Sat, Jul 27, 2019 at 8:29 PM Stephen Adolph
<[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]>>
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.
