engineer

tim   .

                                                      


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.   hunkin

                                                         


cartoonist

 

CONNECTORS

 

THE COMMENTS

I enjoy reading all the comments but apologize that there are so many I canít answer individually. Iím delighted that my new videos have been so enthusiastically received, which is reflected in the majority of the comments. The videos arenít perfect though so below each video Iíve compiled the comments about things I omitted or people thought were misleading. A few comments added wonderful additional information so Iíve included them as well. 

There are obviously many people who use the punchdown IDC connectors. they pointed out that the ribbon cable should feed back through the top additional clamp for strain relief. A couple of people wrote that once installed in a chassis, the rated current is only .25amps per wire! No wonder I don't use them often.

An electrician wrote about his frustration with spring DIN rail terminals when inserting the screwdriver occasionally causes all the fiddly parts inside to fly out. I've had similar problems tightening screw terminals when the metal parts twist out of their plastic housing, but I can see spring terminals could be a worse problem.

Several people felt I should have mentioned the importance of not pushing wires too far into connectors, because you can then be clamping the insulation rather than the wire and making a very bad connection that may overheat.

I didn't know that NASA insist on the use of transparent heatshrink, so the quality of the soldered joint inside can be clearly seen.

A few weeks after finishing this episode I was cursing Molex Microfit, the posh connectors near the end of the video. In a dark awkward space a motor was failing intermittently. I changed it but the fault persisted. I eventually found it was the Molex connector. Unseen, one contact was 'pushing back' when connected. Although the pins do click into place when pushed into their housing, it often doesn't feel that positive. If you do use them, its worth giving the wires a hard tug to check they have located properly. Apparently 'push back' is a very common connector problem.

I didn't think to mention that solder joints should look shiny - if they look opaque they didn't properly melt. Also if re-soldering a connection, put more flux on the iron to avoid 'spikes' in the solder, which often happens to me.

A couple of comments about Heat shrink tubing. Self adhesive heat shrink is great stuff. It provides strain relief and makes a joint completely waterproof. And yet another way to shrink it is with a cigarette lighter. For very small wires, I find non-shrink flexible silicon tubing brilliant.

 

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