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Molex mini-fit vs DT vs ??? connectors

Steve Crewdog

Well Known Member
Patron
Hi all,

I've become a bit stuck with my avionics, my no-longer-available avionics Sea Daddy mentor instilled in me that I need to have units easily remove/replaceable so I don't get stuck on the road trying to solder a wire to a new part in a hard to reach location, cussing up a storm and messing other things up in the process, when I should have installed a quick release connector during the build.

I thought I had the problem solved by going to dsub connectors wrapped in heat shrink, but in practicality it hasn't worked out for me. Fingers and eyes just ain't what they used to be. https://seareybuild.blogspot.com/2020/07/the-big-snip.html

So now I'm thinking about going to the Molex Mini-fit Max series (as used by Dynon on the backup battery connection), especially when I saw I could buy pre-crimped leads. https://www.molex.com/molex/search/...ousings%22%40productname%3A%22Mini-Fit+Max%22

But as always, maybe I'm overthinking it and I've read on VAF that others are having problems with the Mini-fits and are switching to Deutsch DT connectors https://www.mouser.com/new/te-connectivity/te-deutsch-dt-connectors/

So am I overthinking things, and the Molex with precrimped leads are fine, or have others had problems and are making the switch.


Thanks for your time

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Deutsch DTM (avionics gauge wires) or DT (larger gauge power wires). Hands down. Super reliable, way easier to crimp than Molex Minis (there is a reason they offer "pre-crimpled" Mini pigtails - they're a pain to crimp properly). Deutsch has effortless contact extraction without specialized tools. No open ends or rattling around in the connector like Molex. Intuitive spring-loaded plastic locks. And weatherproof seals. You will be impressed by the quality and ease of assembly and positive connect and release with Deutsch. Your labor and peace of mind is too valuable and life is too short to mess with cheesy Molex open connectors.
 
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I too am another supporter of the Deutsch DT and DTM seriese connectors. I used them often in areas outside the cockpit, such as in the wingtips, rear fuselage (for the elevator trim connector) etc. Just watch that if you use the mounts that come with the DTM series (great for riveting in place), be sure to grind a little off the shoulder so that you can unclip the connector from the mount incase you ever need to remove it for some reason.
I have also found 0.1" RC servo connectors absolutely worthwhile. I used them often in the cabin for any 22AWG or smaller application. You can also purchase servo connector locks that clip over the connector if you are not comfortable with the friction fit alone. They are cheap, typically gold plated, commonly available, super reliable and require only an inexpensive crimp tool. Even items like my headset plugs are connected to the avionics harness with these connectors, with no noise issues (my avionics harness is completely removable because I have Dsub connectors to all my fuselage wires and other D subs for my ground and power wires).
Tom.
RV-7
 
Thanks gang, after mulling on it I think there's not going to be a "one size fits all" for me, for instance, a DTM connector will not fit through the hole a LED warning light mounts on, but a Molex 3 will, and I can easily swap out a warning light. On the other hand, for stuff that hard to access and needs to be reliable but does not have to go through a mounting hole, a DT/DTM plug would be an excellent solution.
 
Out of my way!

I went out of my way to get rid of the molex and use DTM. The other options is to use DTM crimp pins with heat shrink sleeving holding them together. Use the molex in your kids toy, that way you will see him more; every time it is not working.
 
Agree with the above. I've been using DTM/DT/DTP connectors in harsh environments for years (vibration, salt, heat) and they are the best. The only downside is they aren't 'aviation' connectors... but once you get past that, you'll find they are superior to other 'aviation' connectors out there (think Molex) :)
 
Funny you mention RC connectors, Tom, yes, I am using rc airplane connectors for my panel LEDs, they're the only thing I found that would fit through the mounting holes.

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Thanks gang, after mulling on it I think there's not going to be a "one size fits all" for me, for instance, a DTM connector will not fit through the hole a LED warning light mounts on, but a Molex 3 will, and I can easily swap out a warning light. On the other hand, for stuff that hard to access and needs to be reliable but does not have to go through a mounting hole, a DT/DTM plug would be an excellent solution.

I also use DTM connectors. They come apart easily, so if you need to run the cable back out through a narrow hole, that is possible.
What wasn't mentioned here yet is that DTM connectors have a rubber seal for each wire separately (you need to use their plastic plugs and close out unused positions). It's a great option to make a sealed connection for loose bundles of wires.
Concerning getting the connector off its mounting bracket, you need to lift the housing with a screwdriver to slide back over the end of the mounting bracket.
 
Right then, you've sold me, especially since the electronics bay is in the nose of a seaplane to be flown by a (seaplane) student pilot. Think I could just use my Dsub connector tool or do I need to spring for the original TE tool?

Thanks


Tom- rc stuff has sure changed, I always used a piece of fishing line and a drop of CA.
 
Right then, you've sold me, especially since the electronics bay is in the nose of a seaplane to be flown by a (seaplane) student pilot. Think I could just use my Dsub connector tool or do I need to spring for the original TE tool?

Thanks


Tom- rc stuff has sure changed, I always used a piece of fishing line and a drop of CA.

That Searey is a perfect application for the Deutsch connectors because they are weather sealed. And I know it has been mentioned before but it is worth repeating. Deutsch connectors can be pinned and de-pinned with normal hand tools within seconds. No special inserter or extractor tool required with the associated frustrations (although they will sell you an official tool if you insist that is basically a small flat-tip screwdriver). The Deutsch retaining mechanism doesn't use bent metal tabs on the contacts like Molex and thus doesn't wear out, bend or break the contact pins with repeated disassembly.
 
More important than the specific brand of connector is the installation. Even the best connectors installed poorly will fail at some point.

Use the correct crimp tool, and use it correctly. A proper crimp, when pulled, will break the wire rather than pull out You also must not over crimp such that you create a neck in the wires. Make a few test pieces and evaluate them.

Second, and as important; Any movement of the wires after installation will cause fretting corrosion. It only takes the slightest movement of the pins against the sockets to eventuate fretting. Make sure the wires and the connectors are well supported such that no relative motion is reasonably possible. Gold coated pins are helpful, but will not make up for poor wire/connector support. The gold is only microns thick and will scrape off with any movement including multiple mating cycles.

Make sure any blade connectors (such as on a forest of tabs) are tight with wires well supported.
 
Hi Steve,

You can use a DMC AFM8 crimp tool for the DTM connectors, then you just need to positioners. If you can't justify shelling out the crazy $ for the legit positioners, there's the to get knockoff versions from a large online retailer (they typically come in a set, and for the price of one or to legit ones, you can get the entire set that will do everything you will ever need).

Tom.
 
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