MTA-100 connectors

We use the 3-pin version to bring power into PCBs, and for fans and such.

They work great. The wire connections are very tough and reliable.

We have an old gun-type wire shooter that's a lot better than the manual punch-down tool.

When you assign the pins, put power in the middle and the grounds on the outside pins, that way, you can't blow things up with someone inevitably plugs the thing in backwards, even though it's keyed.

The hazard isn't so much backwards - it's keyed pretty good that way - it's getting offset by one pin.

I used these in the 90's, when they were AMP. The gun is neat, advances to the next position, makes loading large circuit counts easy.

Cheers

Hey, you don't place the covers!

There's a smaller 2mm series as well.

--
 Thanks, 
    - Win

------------------

** See a lots of them in various bit of audio gear, I also see lots of reliability issues with them too.

Manufacturers love to use many of them for quick assembly of multiple PCBs into a product - creates a huge number of potential failure points.

The contacts are merely tin plated, which is not ideal over the long term for high currents or for small signals either. Time left in storage or any dampness results in bad electrical contact.

Poor crimping on the plugs is also a cause of intermittent faults and burning.

Sometimes using a cleaning fluid is an adequate fix, but otherwise the only solution is to cut the plug off the flexible lead and solder wires direct to each pin - aka hard wiring.

..... Phil

I never knew that there were covers.

The lack of a gold choice is unfortunate.

If one fails, repair by cutting the wires off 1/16-inch in, and punching them into a new connector.

--
 Thanks, 
    - Win

--

  Rick C. 

  - Get 2,000 miles of free Supercharging 
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** I have sometimes seen gold plated ones, on high class products.

** No way.

That is just reinstalling the problem.

Multi-pin connectors on PCBs are there for quick (ie tool free) assembly at the factory - after which they serve no purpose except to create faults.

Hard wiring is a permanent solution.

Something few ivory tower designers know and factory owners don't care much about.

Reliability is not their problem, even during the warranty period.

.... Phil

The covers help keep the wires from being pulled out a wee bit. I do find the insulation displacement connectors to not have as good a grip on the pin as the Trifurcon pins, especially in circuits where you are passing something close to the rated current capacitor of the pin in question.

John :-#)#

"...Oh he'll never return and his fate is still unlearned..." One of my favourite songs when I was a kid!

Perhaps JT is a prisoner of the MTA?

John :-#)#

Do you have to pass the wires through the holes on the cover before shooting the wires into the connector? Looks like a nuisance.

My AC source box will have a 48 volt 500 watt power supply. It will feed the main control board with big wires and fastons. The control board connects to six other boards, three being class D power amps. We'll feed each of them with a ribbon cable from the controller, power and data and analog stuff. Standard ribbons are rated for 4 amps per wire, maybe derate to 2 for luck. It seems to me that a ribbon cable is a perfectly sensible way to distribute power. The flat array has good cooling.

One can order the cable assemblies all made, absurdly cheap.

The board ends can be surface mount shrouded males. Easy.

The Amp shoot-in things are good when the other end isn't a PC board, like a fan or something. Otherwise, too much hassle.

Many of these simply snap over the completed connector - which would be the case for your three wire fan plug as shown in your dropbox image. Looks tidier with the cover. Also resists the wires being pulled out if an idiot pulls on the wires instead of the plug...

John :-#)#

Easy, yes; worked with a company that was moving away from them though (we went with Molex SL and Mini-Fit mostly).

IDC connectors are notorious for bad connections. Great when they work, but frustrating when they fail.

It's like when Joerg noted to a press-fit connector mfg rep, "you claim a

99.7% connect rate; if I have a 1000 pin connector, can you tell me which three pins have failed?"

Probably, an important part this misses for you is, that's a production context -- my example, they just buy the harnesses and let the CM figure them out. And the CM probably has those huge expensive ker-chunk machines that does up crimps instantly and automatically.

That wouldn't cut it for lab use. Your requirements will be more towards a compromise between ease of use (punch-down is cheap and fast; crimps need an expensive tool, and are more tedious to apply), low quantity, and tolerable failure rates. Say if 1% of pins fail after 10 years, that's still not all that many connectors affected, out of the protos and test equipment you've made in that time; and they're easily serviced, if they're still local anyway.

Tim

--
Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Design 
Website: https://www.seventransistorlabs.com/ 

"Winfield Hill"  wrote in message  
news:qlp1990os3@drn.newsguy.com... 
> I've become a big fan of MTA-100 mass- 
> termination connectors (as Tyco 
> TE Connectivty calls them), used for 
> off-board wiring.  Here's a link to 
> the PCB-mount headers at Digi-Key. 
> 
> https://www.digikey.com/products/en/connectors-interconnects/rectangular-connectors-headers-male-pins/314?k=mta-100 
> 
> The male-pin headers have 2.54mm spacing, 
> with standard 25-mil square pins, and the 
> female receptacle "plugs" employ a punch- 
> down system with a range of wire sizes. 
> There are strain-relief covers as well. 
> 
> Sample base p/n scheme: headers 640456, 
> red plugs 640440 #22AWG, blue 644043 #26, 
> green 640443 #28, and covers 643075.  Use 
> base p/n to search, build up full p/n. 
> 
> 
> 
> --  
> Thanks, 
>    - Win

That's my situation. We've made thousands of amazing instrunments over the last 30 years, but few have been used for more than 10 years. Our precious technician died 10 years ago, R.I.P. Since then it's been a matter of assembly simplicity. For us now, if it fails, snip wires, re-punch, and get 10 more good years of life.

It's important to be able to remove and re-attach PCBs, direct soldering can be a disaster. I recently spent two days to repair a pair of failed Keithley 2400 SMUs. These are workhorses in the labs. But they have two large PCBs, with a mass of soldered wires into pads. The holes are too small, so it's a horrific experience working with them. Despite its $2500 value and serious lab needs, I still have a working set of pieces waiting for painful re-assembly, 3 wires done, many more to go.

--
 Thanks, 
    - Win

I had a Keithley 2401. Sent it back.

We use the Keysights in our test rigs.

Also had a Keithley DVM with a small issue. Here's my fix:

--------------------

** Win has misinterpreted my critical post of re his favourite multipins - as usual.

Fact 1.

The "hard wire" solution makes 100% good sense * IF * you are doing repairs for a living on equipment made in another country with NO service backup in yours and which is regularly subjected to harsh operating conditions.

Fact 2.

If the manufacture of high quality ( read expensive) equipment is your game, the solution is to use BETTER connectors.

Yes, gold plated IDC is good for small signal stuff and carefully crimped silver alloy for high current stuff - with plenty of contact area on the pins OR simply double or even triple up on the pins used for redundancy.

IME, gear made using the above methods has very high reliability.

Almost as good as fully hard wired....

FYI:

It is only with the latter type of construction where I see 20 plus year old gear that has been in regular, hard service with ZERO previous repairs.

.... Phil

We've used about 11,000 of those connector pairs over the last 20+ years. They have been very reliable.