Thanks, Why do you have the stubs for the molex on this drawing? I would have thought that such things would be unneeded with the carrier.
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]> wrote: > Here is a messy 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]>> 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]>>> >> 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]>>> >> 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://shpws.me/RngB >> 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>> >> >> >> 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>> >> >> -Josh >> >> On Sat, Jul 27, 2019 at 8:29 PM Stephen Adolph >> <[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]>>> >> 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. >> >> >> >> >
