Soldering newbie

Yes, and I remember looking for bad wraps, and having to solder wire to hundreds of pins when the wire corroded. If you want real fun, try replacing a bad IC socket where every pin has three levels of wrap, and most are daisy chained. A repair that would take minutes on a PC board can take days when you have to remove & replace over a hundred wires.

You clearly had incompetent people running the show. If properly done, WireWrap is as (or more), reliable as soldered connections and you don't daisy-chain the stuff. You should never have to pull more than three wires to replace one. At one time mainframes were all WireWrapped (millions of connections) and were *quite* reliable. Three-high was a no-no, as well, though that was probably for other reasons (impedance). The pins were shorter than some, designed for two wraps only (but a third was easily possible).

I suspect that's some of the issue, the commercial stuff was the mainstay of wire wrap. I've never heard of much trouble with commercial stuff, which may mean it was outside the hobbyist realm, or it may mean it works fine.

Certainly when it hit the hobbyists, about the time Byte arrived, it was treated as a serious thing, so surely the example of commercial wire wrappted equipment was there.

But once in the hobby world, it likely wasn't the same thing. Yes, you could buy actual guns, but for many it was done manually, which I can see would be a source of trouble. Also, those who hadn't had experience likely had problems, just like the person beginning to solder doesn't yet have the experience to know they have bad joints.

I suspect many didn't grasp the concept, and indeed we saw a lot of intermediate work, wire wrap sockets and wire wrap wire, but a cursory wrap around the socket pin and then solder, as if people didn't trust the notion of wire wrapping. I admit that as someone who had already been soldering, the notion of just twisting the wire around the socket pin didnt' seem secure.

Michael

The software for programming a wire-wrap machine was non-trivial. I did it once.

Read punched cards to get the net list. Each card has an IC or connector name, pin number, and net name.

Sort all that by net and look for obvious errors.

Read another deck that maps pins to physical coordinates

Do a "traveling salesman" algorithm to minimize wire length in each net

Sort by level so there are no cross-level wraps

Sort by position to mimimize head travel

Handle color coding, maybe

Output the G-codes and reports.

Wire wrap was awful, in many ways. I don't miss it a bit.

Unlike most hobbyists, it has to be wrapped tightly. ;-) Seriously, that's the major problem, getting enough tension on the wire as it's being pulled around the post so the wire bites into the edges. The other major problem I saw was stripping. Many would nick the wire. Bad news for reliability. We had special strippers that looked like long-nosed pliers with a nick in the jaw (not the blade). Some didn't know that they were special tools and would use them as long-nose pliers. One turn of a nut and they were shot. At $100 each, people got a little protective of their tools.

I wouldn't have expected that it was as good as it was, either. It does take some skill, then so does soldering.

I did that for manual wrap, though used a file (then spreadsheet) for technician use. They then would put in every other wire in a net, finally adding the ones in between. That way, if something changed (or broke), one didn't have to rip the whole net out.

I used to do that with PCB netlists. Tools have gotten much better, though. It's amazing the errors that can be seen by the eye without looking at the actual data.

Unless order made a difference.

Yep. Our techs did that by doing every other wire in a net, then coming back and fill in the 2nd levels.

I prefer it to dead bug, though it's expensive. I used to have some pretty complicated WW boards (one with >6000 wires - memory busses nave lots of wires ;), before PCBs got cheap.

take some wires, take home a sample glued joint?

I remember a Grinnell video processor system that they donated to our lab when I was a grad student, circa 1985. It allowed slow asynchronous scan data to be turned into video in real time, without the nasty bloom problems of the Lithicon tube scan converters that some of my colleagues had been using.(*)

I'd never seen a wire-wrapped backplane before--it just about gave me nightmares, but apparently it worked fine. The thing was a whole 6 foot rack, full. Amazing.

Cheers

Phil Hobbs

(*) (My scan data was all digital, but then I'd taken a couple of years off to work as an EE before grad school, besides having an electronics hobby from an early age.)

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Yes, it could be a problem. I remember a case where we had an inexperienced person doing a R&D wire-wrap job with little supervision. Turned out there was a short from +5 to ground, so we decided to apply a small current from a PS to see if the offending wire would get hot and reveal itself. We cranked up the PS to about 20 amps and nothing got hot, so we had to throw away the whole board since there were too many shorts across the PS.

-Bill

You need a chisel tip instead of that 'pointy' tip.

The point of a conical tip never makes enough contact.

"Tom Del Rosso"

This vid ( I posted earlier) shows how to use a pointy tip to solder regular components like 1 amp diodes to a PCB with plated through holes.

The side of the tip is used and solder is constantly re-applied to the tip.

.... Phil

Not all wire wrap was done with silver plated Kynar. Some was tin plated, and the airflow through the equipment pulled dirty air over the backplane.

Some Chyron video equipment was made with cheap WW sockets. The wiring was so tight that you couldn't do practical repairs. The only thing I could do was press good machine pin sockets into the cheaper sockets to eliminate intermittent. The sockets were packed so tight that they touched any adjacent socket to cram a lot of chips into a small space. Three hinged boards, in a small space. I'll bet the factory wouldn't even try to repair it without cutting wire and soldering.

Yes, you can do it that way, or use the proper width chisel tip to apply even heat and solder the joint properly by applying the solder to the joint instead of the tip. We didn't have anything other than chisel tips in the 100+ temperature controlled Ungar 'Loner' irons at Microdyne. Even the .015" tips had a flat face so you could heat the IC leg & pad instead of the solder.

p.

I call that work barely adequate and certainly wouldn't consider paying for it. Several of the joints don't have solder through the hole. That cutter belong in the recycling bin. I haven't done work that shoddy since I was in grade school.

G²

If the result is poor

Yep. At the very least, one should get an iron/station that has the option of changing tips. I can still buy diff temp and tip profiles for my ancient non heat-adj Weller.

nb

Sorry, Phil, I have to disagree. Every quality control manual I know of, NASA, MIL, etc, in the case of plated through holes, insist on complete hole filling, plus a fillet each side.

Many PCB designs (mine included) don't have enough pad area to be satisfactory without solder penetration. Pads large enough to be viable on their own, waste real estate.

I still have a pair.

I can no longer remember who made what.

My first soldering irons for some reason lasted a very shrot time. I wasn't abusing them, but they were cheap and overheated and soon died. I was too inexperienced to figure out why. The first was new, a birthday present, the second was used, someone gave it to me with a new cord attached.

Somewhere about then I was given a Weller soldering gun, useful because tubes were still being used. That gun has lasted me all these decades, it was used when I got it, a few scrapes and burn points in the cord. The cord has a lot of electrical tape on it now, and some years back I put some epoxy on some places where there were cracks (though no structural breaks). Finally a couple of years ago it fell off the bench, and the lower part of the handle actually broke off. I drilled some small holes, used some wire to "sew" it back together, then covered with epoxy, still working fine though rather ugly looking.

So I decided to buy a new one, but they cost a lot now. I wait, and find one at a garage sale for ten dollars, in a case with some accessories, though a somewhat later model. Then last year I found one identical to mine, but in much better shape, in the original box, for five dollars.

But after those first two soldering irons died prematurely, I went with the system Radio Shack had at the time, a handle, a heating element and a tip. I think Ungar made them, but they were branded Radio Shack. That was great, except I kept dropping the iron, and the tip would break off. The ones I liked (there was a variety) threaded into the heat element, and thus without the means of drilling out the rest of the tip, the heat element was junk too. I slowly got better, dropping the iron less. That lasted about 20 years, actually the handle is still fine. I replaced it with a newer model, direct from Ungar, this time having a third prong in the AC cord.

That ones still working. I actually made up a stand for it, complete with a light dimmer to vary the heat, even though I've never found that feature all that useful.

Then a few years ago, I found a Weller soldering station, the light blue kind with the magnetic tip that kept things the same temperature. Only five dollars (it was the same place I'd found a drill press vice a couple of years before), too cheap to turn down. My first temperature controlled soldering iron in all these decades. Oddly, the switch had gone bad, the previous owner adding some wire to bypass it. I thought of various schemes to replace the switch, it's square so I didn't think I had a direct replacement, then thought of the AC power strips I'd found a box of lying on the sidewalk one night. The switch form one was a fit, so I did the transplant, and the Weller soldering station is like new.

It's kind of neat, but I like the Ungar, I'm used to it, I'm used to the feel in my hand, so though I have both set up right next to each other, it's the Ungar I turn on much of the time.

Michael