(Topic ID: 209727)

Display issues

By bbhenry2000

6 years ago



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solder joint (resized).png
display pins to resolder (resized).jpg
#1 6 years ago

I have an issue with the player 4 display on my Evel Knievel. It doesn't display anything until it's the 4th player's turn (including during attract mode when all player displays show the current high score). When it does display during 4th player's turn, the last two digits do not show. For example if the score is 123,456.... only 1234 shows. Does this sound like problem with the connector pins or the display itself? Any help on figuring out how to diagnose would be thoroughly appreciated.

#2 6 years ago

With the machine off, pull the display and look at the large header pin solder joints on the back-side. Often a few of them are cracked or have cold solder joints. You can usually see the cracks in the solder around the pin itself. Years of dust/dirt might mean you have to brush the solder joints off quick with an old toothbrush to inspect better. Don't use the wife's toothbrush

Easiest thing to do then with a display with issues is throw it into another player position and see if it exhibits the same issue. Best to throw it in Player 1 position since the wiring from the MPU starts there. If it works fine, try a "working display" in the Player 4 position. If the working display has issues at Player 4 position then you're problem is likely at the Molex connector.

As far as connector issues, some used crimp terminals and some used IDC (wire pushes into the connector from the top). The terminals can fatigue over time, or they can get corroded. On the IDC style, the wire can sometimes work loose from where it pushes into the connector. If it's a connector issue you'll need to fix the bad wires or bad crimps to ultimately resolve things.

#3 6 years ago
Quoted from acebathound:

With the machine off, pull the display and look at the large header pin solder joints on the back-side. Often a few of them are cracked or have cold solder joints. You can usually see the cracks in the solder around the pin itself. Years of dust/dirt might mean you have to brush the solder joints off quick with an old toothbrush to inspect better. Don't use the wife's toothbrush
Easiest thing to do then with a display with issues is throw it into another player position and see if it exhibits the same issue. Best to throw it in Player 1 position since the wiring from the MPU starts there. If it works fine, try a "working display" in the Player 4 position. If the working display has issues at Player 4 position then you're problem is likely at the Molex connector.
As far as connector issues, some used crimp terminals and some used IDC (wire pushes into the connector from the top). The terminals can fatigue over time, or they can get corroded. On the IDC style, the wire can sometimes work loose from where it pushes into the connector. If it's a connector issue you'll need to fix the bad wires or bad crimps to ultimately resolve things.

Thank you. I will try that tonight.

#4 6 years ago
Quoted from acebathound:

With the machine off, pull the display and look at the large header pin solder joints on the back-side. Often a few of them are cracked or have cold solder joints. You can usually see the cracks in the solder around the pin itself.

On top of the header row, check the row of pins on the glass display as well. I see those have cracked solder joints as well.
solder joint (resized).pngsolder joint (resized).pngdisplay pins to resolder (resized).jpgdisplay pins to resolder (resized).jpg

#5 6 years ago

Ok, it's definitely in that display as I switched displays with player one and the issue traveled to player one position. I will have to pull it again after I pick up a magnifying glass as my vision sucks with the small stuff. Thanks for the advice, thusfar. I appreciate it.

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