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Old August 23rd, 2006, 08:53 AM   #1
nighthawkjw
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Question TI 500 Series Connector Problems

I am facing an old problem that started with a poor design from TI. Their Series 500 IO modules (500-5055 & 65 - the earliest ones) have a very poorly designed field connector to the top and bottom of the modules. These connectors, both on the module and attached to wiring, have deteriorated over the years to where the plastic is brittle, broken and the connectors no longer hold to the modules any more.

On the module side, the tabs on each side of these connectors are missing, so that the mating wiring connector no long snaps in place and the bottom wiring connector can fall away with vibration. Also on the module side, with wear and tear from plugging/unplugging these connectors, the plastic parts that prevent the connector from flexing have broken and are missing. Each connector has four plastic prongs that go through the cicuit board and attach to a plastic piece on the other side -- these are what break and go missing, so the connector can flex, making a poor connection.

On the wiring side, the prongs that provide a small amount of holding between the two mating connector, these break off.

The end result is that many systems using these IO modules are experiencing a lot of problems with the connectors coming loose.

The question is, what to do about it? My stock of good salvage parts is now gone, so I have no more unbroken plastic parts. Siemens quit supporting this stuff a long time ago. Any suggestion aside from retooling is welcome. This question is probably more advanced than this forum, but I have few places to turn.

One thought is that when the module is connected, a spot of hot glue carefully applied could act as a holding agent to keep the connector from working loose. Only problem is that this can be messy and if not applied carefully, it may make a poor connection worse!

Any other ideas?

Jimmy
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Old August 23rd, 2006, 12:02 PM   #2
Ken Moore
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The TI 500 series came out in the eighties, TI replaced the 500 series in the early nineties, with the 505 series, which cured a lot of the problems with the older modules.

Have you considered upgrading to 505 series I/O?

The only thing I can think of is to contact some of the TI refurb/repair outfits.
They may have surplus connectors.

www.sterlingservices.com (located in Mathews, NC)
www.plccenter.com
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Old August 23rd, 2006, 01:23 PM   #3
Ken M
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Hi Jimmy

I remember seeing this general problem a number of times but each time the solution seemed to vary from installation to installation. Some people I remember fixed it with tie-wraps (cable-ties?), some used tape etc. There's no proven fix that I know of. I don't remember anyone resorting to glue. That seems pretty permanent, and if you can accept gluing the mdoules and connectors why were they being plugged and unplugged all the time in the first place?

To give some idea of the age of these systems (and how the problem came about) the 500-series I/O was created when 8-points per module was as far as technology stretched. That must have been some time in the late 16th century. Because of that, TI had the great idea of putting all the field wiring on the backplane, not the module itself. This made removing a module really simple - nothing to disconnect! Then the years rolled by, and people wanted 16-point and eventually 32-point modules. Big problem. How to get 32+ terminals on to the backplane in the same space that originally held 8+. And what about compatibility, new modules in old systems etc. So this was when TI added a connector to the new 32-point modules.

I suspect they knew themselves from the outset that it wasn't a neat solution. They couldn't have the connector on the front of the module (not enough room) so they ended up with 16 points entering from the top of the module and another 16 from the bottom. Plus the original connections on to the backplane. None of these old systems would ever win a prize in a panel beauty contest. Even fresh out the workshop they looked like a squirrel had been in the wiring!

Unfortunately these connectors were anchored directly on to the circuit board, and the combined torque of 16+ wires all loomed together often resulted in twisting forces which neither the connector nor the strain relief (huh!) could stand.

As you say this was an inherently bad design, but I'll bet marketing had more say than engineering when it came to the decision. "Redesign and replace every single backplane?! You gotta be joking! Make a fix for the modules." And then as Ken Moore said, along came the 505-series. And the solution was now "oh yes sir, an I/O upgrade will resolve that issue ..."

Still, at least you've had your money's worth from these old 500's!

Regards

Ken
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Old October 11th, 2006, 07:03 AM   #4
nighthawkjw
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Thumbs up TI 500 Series connector woes solution!

As has been noted, there was a great leap from 500 to 505 as far as wiring terminals and connectors was concerned. However, there was an in-between improvement... The right-angle connector was a definite improvement to the pitiful original connector that the 500 series was plagued by. The right-angle connectors not only mated much more positively, but also had a better screw terminal for the wires. While it didn't improve much on the design flaw, it was a less-weak link.

My solution to the problem of the original connectors is to replace them with right-angle connectors, still available from TI! When I do a repair and the connector is trashed, I remove it, install the male side on the PCB, and include the mate so the end-user can replace the crappy connector on the field side. So, if anyone needs the part numbers, I will get them from my parts person and post them.

Jimmy
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Old October 11th, 2006, 07:11 AM   #5
Ken Moore
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CTI now has an adapter that allows 505 series I/O modules to be used in a 500 series chassis. http://www.controltechnology.com/pro...0-io_adapters/

Some re-wiring will be required, but you don't have to upgrade the entire system.
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