[cctalk] Back-plane wrap (was Re: Re: Antonio's call for donations (was LCM auction))

On 8/30/2024 7:25 PM, cz via cctalk wrote: Some of the older (single-sided especially) DEC back-planes were wrapped with heavier gauge wire, which needs a different tool. The newer back-planes seem to be wrapped with 30 gauge wire. You can tell the old connector blocks, as the pins appear rectangular, rather then square. There are all kinds of opportunity for optimizing routing for distance, cross-talk and and other esoterica. One thing that's worth doing, though, is to wrap for a max height of two, and such that all the connections (except possibly the last end of a given signal) are at the same height. So, if A B C and D are to be connected together, you connect A to B, then C to D (thus all at the lower level), then put the connection of B to C at a higher level. This dramatically cuts down on the amount you have to *unwrap* to fix something. Avoid situations which cross the height boundary, because then you have to keep unwrapping stuff you'd rather not, to expose the buried lower side. If you are wrapping by hand, you can be assured that you *will* make mistakes and have to fix something. I predict you will also find that you are really sick of wire-wrap long before you are done. These days, PCBs are inexpensive, and less error prone (in the sense that you almost always end up with exactly the connections in the netlist). OTOH, connectors are expensive and hard to reuse when soldered to a PCB. So you've got to be really confident of your netlist. You might consider investing in a tool where you pull the trigger to do the wrap. You'll probably get a more consistent result, and significantly fewer repetitive motion issues. Hope that helps! Vince