Molex vs Terminal Block Connector

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chrisenglish

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I am getting ready to start a new build ( DR - MQ5 ) and wanted more experienced opinions about Molex vs Terminal Block Connectors. My previous builds using molex connectors and I remember really not liking them. I know that the TBC's will be more expensive but I really don't trust the Molex.
Any thoughts?
 

abbey road d enfer

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Molex are known to become dirty over time.
What kind of terminal blocks are you considering?
I use tyerminal blocks for mains and PSU connections, but for signal I use XLR's or Phoenix.
 

chrisenglish

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maybe something like this... I like using the screw to secure wire instead of the crimping.. TE Connectivity
 

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fragletrollet

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I've had my share of frustration with Molex. I mean, if you're crimping tools and technique is good you can get good results, but it does take a fair bit of time, and in my experience, is the biggest source of something going wrong during a build.

Terminal blocks are great, just be sure to use properly sized ferrules for the wire size you're using. So much easier than molex'es...
Been looking into DIN-rail blocks lately, pretty cool modular systems available.
Oh, and just ordered these a little while ago: JST XHB, a strengthened version (supposedly, with an extra locking tab) over the allready pretty good JST connector system, that far surpasses molex, atleast the 2.54 sized one, by far in terms of how secure I feel my connection ends up.
 

abbey road d enfer

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I've had my share of frustration with Molex. I mean, if you're crimping tools and technique is good you can get good results, but it does take a fair bit of time, and in my experience, is the biggest source of something going wrong during a build.
My frustration is not so much the crimping than teh fact that the NiSn plating disintegrates and results in a completely oxudized contact.
Oh, and just ordered these a little while ago: JST XHB, a strengthened version (supposedly, with an extra locking tab) over the allready pretty good JST connector system, that far surpasses molex, atleast the 2.54 sized one, by far in terms of how secure I feel my connection ends up.
Do you have any experience about their durability (again DC is teh enemy).
 

Script

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I use both, terminal blocks and molex. Power mostly terminal. Molex when it's many boards and wires.

Molex I like when troubleshooting and for revisiting / extending builds. (Disconnecting and reconnecting a dozen and more wires to terminal blocks can be a nightmare.)

I crimp the wires and add some solder for extra strength before inserting into housing. Also some shrink tube to hold wires together near housing. Takes time, yes, but never had a connection going bad, even after decade and a half.

How many years before oxidization ?
 

abbey road d enfer

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How many years before oxidization ?
It actually depends on many factors. It can be as small as a couple of years if used in touring, and also, as I've already mentioned, DC.
Many Soundcfatf PSU's have needed replacing the Molex.
I have a Focusrite ISA430MkII that I've retired after 7 years, waiting to replace the xfmr connecions with term blocks. I don't relish the idea.
 

Rob Flinn

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I have not experienced problems with the small molex connectors. The bigger ones, as used in MCI gear are a big problem though.

I only crimp the small ones & never solder them. If the plating becomes an issue it is possible to get gold plated pins & crimps I believe.

I never solder Dsubs either nowadays. The connection when it's crimped is just far superior.

I don't like using those green terminals unless it's for power connections, they are just too big for signal wires IMHO.
 
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TwentyTrees

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Like Rob, I crimp and don't solder Molexes (KK series), and if I have to use them for DC I use the gold plated ones. Not had one fail yet, though I've only been using them for maybe 4 or 5 years so I'll keep you posted!

Terminal blocks for power generally though, all the way.
 

calaverasgrande

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I use both. I avoid Aliexpress and similar dinky parts because I don't trust the mechanical durability or plating.
 

warpie

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For what sort of dc voltages are we talking about? 5V? 15V? 30V? Or it doesn't matter?
 

ccaudle

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I crimp the wires and add some solder for extra strength
Soldering a crimped connection can actually result in broken connections if used in an environment with movement or vibration. Soldering a crimp is explicitly forbidden for aerospace use, for example. Look for the NASA wire connection handbook online, it has a lot of good information on wire crimp quality. The summary is that if the crimp is done properly, there is no space for solder to flow, so all it does is add a strain point by joining the strands right at the end of the connector.
Found a copy here for you:
Workmanship Standard for Crimping, Interconnecting Cables, Harnesses, and Wiring

This Molex document also has some good info on inspecting crimp connections to verify they are correct (found it at Digikey, but presumably the same doc is available at the Molex web site somewhere):
Molex Quality Crimp Handbook
 

Rob Flinn

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Soldering a crimped connection can actually result in broken connections if used in an environment with movement or vibration. Soldering a crimp is explicitly forbidden for aerospace use, for example. Look for the NASA wire connection handbook online, it has a lot of good information on wire crimp quality. The summary is that if the crimp is done properly, there is no space for solder to flow, so all it does is add a strain point by joining the strands right at the end of the connector.
Found a copy here for you:
Workmanship Standard for Crimping, Interconnecting Cables, Harnesses, and Wiring

This Molex document also has some good info on inspecting crimp connections to verify they are correct (found it at Digikey, but presumably the same doc is available at the Molex web site somewhere):
Molex Quality Crimp Handbook

This is exactly the point. When you solder if the wires move at all then the connection eventually breaks because the wires become stiff & brittle. When you crimp the connection part of the crimp makes the electrical connection & another part crimps round the insulation of the cable which makes the connections much more resilient to movement. This is why I only crimp Dsubs now, it is far superior. In the crimp Dsub if wires becomes detatched they are much less likely to short to other pins because the pins are sunken into the housing. Dsub crimps are more expensive than solder ones but they take less time to do so if you are getting paid there is not much between them cost wise. In the crimp Dsub if wires becomes detatched it is less likely to short to other pins because the are sunken into the housing.

I also never solder a wire that is being used in a compression connection like a screw terminal for example. You get a phenomenom called cold flow, where the solder changes it's molecular properties under stress & moves making the connections loose. This is particularly dangerous if the connection is passing a high current & can cause fires in really bad examples. If you don't believe me solder a stranded wire & then pinch it tightly with some pliers. You will see the solder goes white & powdery.

 
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drtechno

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I am getting ready to start a new build ( DR - MQ5 ) and wanted more experienced opinions about Molex vs Terminal Block Connectors. My previous builds using molex connectors and I remember really not liking them. I know that the TBC's will be more expensive but I really don't trust the Molex.
Any thoughts?
the terminal block and phoenix connectors are the best. Molex connectors sucks because they can't handle constant current and the contacts self de-rate with temperature to the point of heating up and self destructing. CA_1645S.jpg
 

Rob Flinn

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the terminal block and phoenix connectors are the best. Molex connectors sucks because they can't handle constant current and the contacts self de-rate with temperature to the point of heating up and self destructing. View attachment 82078
I don't think that's derating with temperature. Switches or contacts should have close to zero resistance or they will heat up. The heating up is a function of the contact failing rather than the other way round. IMHO the contacts have either lost their springyness & are no longer tight or they have corroded. Either way there has been resistance introduced & that combined with a high current is what causes the heat. P=(IxI)/R.
 

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