Repairing a female Molex .156 Found on Pinball Games

I recently purchased the pinball game Funhouse, my all time favorite. The machine was refurbished and looks brand new inside and out.

Shortly after receiving it I noticed that coin door functions were working erratically. Most importantly, the buttons used to program the unit are on the back of the coin door were misbehaving.

Researching the Problem

The coin door wiring harness comes into the game and connects to the coin door interface board:

Pulling the connector off the door I could test for continuity, but clearly just looking into the connector some of the pins inside looked different than the others. Turned out they were broken and might or might not make an electrical connection.

Using a tiny screw driver, I was able to press against the metal tab (circled) of the pin to allow it to be extracted:

A good pin should look like this:

Several of them looked more like this, the spring part had snapped off:

Clearly, this connector needed to be rebuilt.

Obtaining the Parts

There are several pinball specialty companies out there that sell these parts. I ended up purchasing parts from Marcos Specialties and Pinball Life. It was from these sites that I learned these are Molex .156 connectors. You can also find these parts (except the key post) from  Mouser, Digikey, and Jameco.

From Pinball Life I purchased:

Tools

Besides the small screw driver and a wire cutter, I needed a crimper plus I went with a fancy wire stripper that allows me to consistently strip insulation at the same length. I don’t want to cut any more wire than absolutely necessary from this old pinball game.

Building the New Cable End

I’m not going to spend time going over how to build the cable ends. You can find a general overview of the procedure here:

How to re-pin Molex connectors

A procedure for crimping the terminals to the wires can be found here:

MOLEX & OPEN BARREL PIN CRIMPING

Some Additional Notes

I wanted to make sure my new cable end was keyed so I could not connect it upside down. I guarantee some day I will try to. That is the function of the polarizing key. I inserted it into the same terminal hole as it was on the hold connector:

With the polarizing key installed, it was then just a matter of extracting the terminal from the old connector, cutting the old terminal off, stripping, crimping the new one on, and inserting the terminal into the PROPER hole in the new connector.

Here is the completed connector. Note that there is one hole without a terminal.

The connector is then connected back onto the coin door interface board and tested. Success!

After completing the project, I decided to see if my old IWISS Dupont pin crimper would work. It does, and it will make both crimps at the same time.

 

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