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]> 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]>> 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. >> >> >> >
