Crimp Connections Made Less Painful

by , 01/03/15.
Copyright 2015, all rights reserved.

SS Pinball machines have connectors on every board. Sometimes they have to be replaced. Replacing the connectors and crimping new wires in place can be a difficult procedure, but with a little practice, this rather annoying project can be completed successfully.
A sure sign that it is time to replace a connector is when it burns, like that on the right. When replacing these connectors, it is important to replace both the plug and the pins on the circuit board.

Burned Connector
Sometimes one may come across a burned connector like this one

Replacing the pins on the board is pretty straightforward: remove the existing pins by desoldering. I find it easy to heat each pin with a soldering iron and pull each individual pin out one at a time with needle nose pliers. Then clear the solder holes with solder suckers. Insert the new pins. All done.
A supply of header pins can be purchased from GPE. Most of the time, the pins will be either 0.156 (Part Number: 26-48-1241) or 0.100 (Part Number: CH100-40T-0.318). These pins can also be purchased from the other suppliers listed on this site.

Supplies Needed
Click in image for full sized picture

Prior to crimping a new plug, obtain the following supplies: (GPE and search "connector plug 0.156" or "connector plug 0.100"). It is not necessary to get the exact size as they can be cut, so I usually get 20 pin or larger plug. Since these are cheap, I get a supply of them. Part Number: CS156-20-LR works for 20 pin 0.156. Part Number: CP100-20-LR works for 20 pin 0.100. Or get the smaller or larger sized ones that are exact for your application.
Note that there are other size connectors in your pinball machine, but these are the most common ones in Bally, Stern, Data East / Sega and Williams games.
Gottlieb uses edge connectors in many games. The procedure is similar except header pins to not need to be replaced.
Molex crimp

Also needed are the connectors themselves. For 0.156, I use Part Number: 08-52-0113 Trifurcon Terminal Pins. For 0.100, it is Part Number: 08-52-0123.
Gold or Tin? These pinball machines used tin connectors originally. I stick with tin. If you decide to go with gold connectors, do not mix the two: the connector and the pin must be the same.
Also needed is a crimper. Waldom/Molex crimper WHT-1921is a good one. Radio Shack used to sell a #64-410 which is pretty bad, but it is the one I use because it was cheap.
Also see "Addendum" section below for additional supplies.

Also needed are wire cutters and wire strippers. In the above picture are my favorites, but you can purchase those from your local store.
First step is to take your new plug and mark it up. Note that is should be oriented the same way as your current plug. There are slots on one side of the plug and the new plug slots must be placed in the same side as the old plug.
I then mark up the new plug to indicate the wire number (see the circuit board for # 1 to # ?), plus place an "x" where there is not a wire. I also indicate the "key" which is where there is a pin removed from the circuit board. This key makes it nearly impossible to mix up plugs.


new plug

The new plug with wire markings. This helps to insure that I don't put the wire in the wrong hole.

Next, remove the wire from the existing plug. Most plugs used by pinball manufacturers were not crimped in place, but pushed into a pin. These are easy to remove: just pull on the wire. Cut off a small section that is damaged. Remove insulation. The amount needed is to insert far enough to reach the first crimp. In theory, the second crimp should catch the insulation. However, if it also crimps on the wire, I usually leave it as is. These plugs are not removed too often so strength is not as important as a good electrical connection.
To the right is a 0.100 connector. The wire should be cut to make it to the crimp connector closest to the contact. The crimp to the right should be for the insulation.

connector

Typical 0.100 connector

pre-crimp

The "pre-crimp"


It will be necessary to insert the connector into the proper crimper slot. Sometimes the fit is too tight. If that happens, I pre-crimp the connector just a little bit so it fits into the crimper.
Next, I insert the connector into the proper slot. It is upside down, so that it forms a "U". See the picture to the right. The connector must stick out the other side so as not to be harmed while crimping (see second picture).
Next, insert the wire into the crimper. Then squeeze the crimper. With my style crimper, it is necessary to squeeze as hard as I can. However, with some crimpers, it is possible to squeeze it to hard.

in crimper
Click on the picture for a larger image.

insertion depth

Wire inserted

The wire is inserted into the crimper.


insert crimped connector

Inserting the wire with the crimped connector into the plug. Click on the photo for a larger image.

After crimping, pull the wire and connector out of the crimper. In many cases, the crimped connector will feel stuck in the crimper. Push the connector out of the crimper. Then check the crimp by pulling a little bit on the connector and wire.
Note that the first crimp must be around the bare wire. The second or outside crimp is supposed to be on the insulation, but if it crimps the bare wire, don't worry about it too much. It will not be as strong, but it should be OK.
On the image to the far left, the connector is being inserted into the plug. Note the small tab on the crimp connector. It will lock into the slot at the top. You should hear a slight click as it snaps into place.

inserted connector
Wire inserted into plug.
Click on photo for larger image.

The image to the near left shows the inserted connector. Looking through the slot, one can see the metal tab holding the crimp in place.
Note that if the tab does not hold the crimp in the plug, it is possible to carefully bend the tab out using your fingernail. Through trial and error, it can be possible to get the connector to click into the plug. If it does not click into the plug, it will be necessary to redo the connection. Cut it off and try again.

Addendum:

If it is necessary to remove a connector from a plug, take a small screwdriver, like a jewelers screwdriver, and press down the metal tab. This will allow the connector and wire to be removed.
Plugs like the style here can be reused if not burned or otherwise damaged. However, it is not advisable to reuse the plugs that come with the pinball game as those are not designed for crimp connectors.
There is also an extraction tool available from GPE, Part Number: 11-03-0016 for 0.156". Also available is a kit containing most of the parts needed, Part Number: 76650-3008.

key plug Most header pins have a pin missing. This is a "key" so that plugs of the same size cannot accidentally be inserted incorrectly or into the wrong place (see right). GPE sells two types of plugs for 0.156" keys, Part Number: 15-04-0297 and Part Number: 15-04-0297-STRIP. Purchase the one appropriate for the style plug you have. For 0.100" it is Part Number: 15-04-9209.
On a pinch, I have used a dab of clear plastic glue, like that on the left plug. But the proper plastic plugs are the best bet.
To the right is the completed plug, ready for use.
Completed plug
Click on image for a larger picture.
Note the key - missing header pin.

For comments, suggestions and corrections, please email:

Additional Resources:
Molex Good Crimps
Clay's Guide to Crimping

Return to the Introduction to Pinball Repair and Maintenance

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