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Re: Do it anyway
dbell5   10/22/2013 4:48:43 PM
"Why were the boards wire-wrapped?" Because that was the technology of choice!

I encountered the same (technical, thankfully, not administrative) problem, I'm guessing 5-10 years before Mr. Morris. We didn't have 74xx devices; these were 0.5" square modules, each with a single TO5 can DTL device, plugged onto wire-wrap panels a rack wide and about 4 feet tall.

Control Bay #1 came out of Engineering, rat's nest style, and after considerable debugging and re-wiring, worked to spec.

That was the cue for the next 10 identical racks to be built in Manufacturing. Except they weren't identical; they were "neat". And didn't work.

Interestingly, this was also a contrct with the Navy...


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bobjengr   10/10/2013 5:39:47 PM
I had a very similar situation some years ago working for one of the "majors" in the appliance industry.  I was new to the company and an ME.  (Those two facts are important.)  Wiring harnesses were designed to carry low voltage control circuits and high voltage; i.e. 240 volt A.C. supplying the bake and broil elements in the oven cavity.  We had huge issues with interference confounding the ERC (electric range controller).  This was in the days when bit generators were used and long long before capacitive touch equipment became available.   I mentioned to my supervisor the fact that low and high voltage conductors should not be in the same wire bundle.  He blew me off indicating that I had attended a public university while he had attended MIT.  My concern was "noted" but not taken seriously.  I was really POed but carried on like a good soldier.  I found out later he called one of his EE professors at MIT and received the same advice as I had given.  He never came back and apologized for being somewhat condescending. NEVER.  Believe it or not, that actually allowed me to score one small point with the guy. 

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RE: Do it anyway
AnandY   10/8/2013 8:06:57 AM
It's devastating how graduates venturing into their job professions are viewed as juniors and are often looked down upon. Yah, experience is important but whether the equipment you are using is in shape or not, your failure is always viewed as incompetence by your seniors. It's high time we gave the fresh blood in the professions a chance to mature by listening to them and nurturing them.

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Re: Do it anyway
ndgraybeard   10/6/2013 12:05:16 PM
There were two kinds of wire-wrapped boards in use in low-volume flight simulators, at least at Evans & Sutherland, where I worked in the early '80's.  The type that allowed rats-nest routing was the type where the wire-wrap was on the opposite side of the board from the 7400-series components.  All components were socketed, with the wire-wrap posts forming part of the socket.  As has been mentioned, power and ground connections were sometimes problematic in this stye of wire-wrap board.

To save space in the rack and pack the boards on tigher pitches, and to get more reliable power and ground connections, the second type of wire-wrap board put the wire-wrap posts on the same side as the 7400-series components, which were soldered into the board.  In this style of board, routing was not rats-nest; instead, the wires were routed in channels between the components.  Cross-talk _was_ a problem in this style of wire-wrap board.  The operator who wrapped the wires had a choice, whether to route from point A to B.  The wire could be routed vertically and then horizontally, or horizontally and then vertically. So two critical signals which would cross-talk if they were in close proximity, _would_ be in proximity in boards built by some operators, and would not be in close proximity in other boards. 

Usually the engineer didn't know, before the fact, which signals would interact, so these problems would usually only be found by de-bugging and re-wiring.


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Sometime the REMFs ARE the problem!
oldtimer8080   10/5/2013 5:12:52 PM
Seriously, some military officials think they can change a physical law by ordering it. Many become cops and try to do the same thing which becomes an epic FAIL, especially when it gets caught on video and broadcast on YouTube..

But I digress

My first ATE job was manually fixing and calibrating the  Pin Electronics cards in the ATE built by different mfgs for AMD. Remember MIL-SPEC 883 required traceability to NIST and that was why MIL-SPEC parts cost 10x more than the civilian product.

Everyone hated to repair those damn cards. The good techs ( like me ) got the regular Test floor running properly and were " rewarded " with fixing and testing spare PE and power cards in that extra time we had.

This problem followed me all over my jobs in Silicon Valley and I rose to the top of my field and was a Senior Calibration Technician. The Test Engineer Degree was not available and that became the sole reason I wasn't made an Engineer by the HR people in Silicon Valley.

When Cray Research hired me to create a way to test ICs from their brand new $5M wafer fab, I created a test system out of an older Genrad PCB tester they had. The next step was to build a Parametric Analyzer out of some Keithley equipment they had at Cray.

Now, Keithley has a whole division dedicated to test; we never patented the concept because we needed a test solution for our fab area.

I finally made Test Engineer at Cray.

I also was able to solve the unwanted job of calibrating PE cards by having my fellow test engineer develop software that calibrated the ATE we finally bought design the progrm that just needed a " gold " device inserted into the socket on the test head.

Then I went on to better things at Cray, like " inventing the Internet "...











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Head Strong
wbswenberg   10/5/2013 11:39:15 AM
When at the E company I worked on a Digital Interface Unit.  It bridged the gap from old micros in test equipment to fast in production equipment.  It had mutiple ports, direct and multiplxed addressing and data buses.  The problem was mostly that the power supply had lost some EMI protection and certain chip were sensitive to it - both conductive and radiated.  I could not get a replacement that should have been a linear and not a switcher.  Luckily there was software trouble shooting using mild coruption of verification code.  I would run walking 1s and 0s and other patterns.  Using a logic analyzer I would check the input and output of chips.  The big labor was pinning out the clamp-ons cause every chip is different.  Some of the fixes were added caps.  No decoupleing caps at all in the design.  In another case I used copper tape.  It would work with the lid off but not on.  Radiated EMI from the power supply.  I talked to the guy that ended up as a super Tech.  I did not relaize he was the designer and builder. And he was very good rose to the max and rightfully so.  But he was unhappy with my fixes and pulled them out.  So I got to redo them.  After I guess the fixes were left as we needed the equipment.  

James Patterson
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Re: Military intelligence?
James Patterson   10/4/2013 6:27:23 PM
I have worked with a large number of military (and ex) people. Those with a sense of humor get ahead and get promoted. Those with out that, are usually not very successful.

If your boss accuses you of incompetence then you need to leave. His mind is made up and he is not supplying you with either the motivation or the resources to succeed in your current position.

Humor is good. Hubris is not. Glad you moved on to a sucessful career!

User Rank
Re: Military intelligence?
Watashi   10/4/2013 5:19:24 PM
It sounds funny but you are also correct that it is not.  It is actually a statement of fact that acknowledges the things that drive decisions in the military are not always obvious to civilians. 

A civilian engineer generally looks at a problem based on a specific requirement set.  A military technician must be cognizant of a much larger requirement set including wide ranging considerations based on how, where, when, how often, etc... the system will be employed.

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Re: Military intelligence?
Watashi   10/4/2013 5:02:11 PM
I found it humorous, although dated.

As a former US Navy Fire Controlman (weapon system technician) I can attest to the fact that you get a variety of technical competencies in the service.  Generally, I noticed that guys who liked the work (like me) were left to work on the system(s) while the lesser technicians caught our collateral duties.

However, it was a double edged sword – the competent were recognized at the division level for being key personnel, but the less competent were more active with the rest of the ship and oftentimes got recognition from the higher levels.

It is similar in industry – the smart guys are in the lab doing great things and usually don't get any visibility, while others handle reporting up the line and reap the praise from on high.

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Re: Do it anyway
tekochip   10/3/2013 8:57:30 AM
At first I was going to say "no", but then I remembered being hunched over a light board with spools of different sized tape slipped over my wrists like bracelets.  The back of my left hand was decorated with various scraps of tape for filling in land areas and laying out a simple one-sided board for an automotive switch could take a couple days, not including sending the artwork off to the photographer to be reduced.  Making a board was labor intensive, expensive, and there was no guarantee that the board you laid out would match the schematic.  Now, just imagine if you had to make a change.
We are so spoiled now.

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