The PinLED Display doesn't show anything

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Please check the following points to rule out that the fault is somewhere else in the pinball.

1. Is the Blanking signal present? The Blanking signal is one of the most important signals in the pinball machine. It prepares the gates of many IC's. The Blanking signal inhibits the gates and prevents the controlled lamps, coils and the display to burn up. If an error occurs and the CPU stops working (hangs up) the Blanking signal drops low.  This will stop all working lamps, coils and the displays. How can I check the Blanking signal? After you switched on the pinball machine look at the controlled lamps on the playfield. If they are blinking everything is ok with the Blanking signal. On the PinLED Display board the Blanking signal is present at J4 Pin 2. Your measurement will be a high signal (+5 Volts).

2. Is the +5 Volt  power supply alive? Every IC requires a certain amount of electrical power to operate. This power is supplied by the +5 Volt power supply of the pinball machine. Please check J3 Pin6 on the display board. You will measure the +5 Volts at J3 Pin 6 and 5 (Ground). Is it not present check the fuse on the power supply board. If the pinball machine is working the +5 Volt is correct. In this case the fault can be a broken wire or a loose connector / plug.

3. Are the cables to the display board connected properly?  Please check all cables between the system11 board and the display. A popular mistake is the exchange of the first pin of the flat cable. The red wire indicates Pin1 of the flat cable. On the display the red wire must show to the left and on the system11 board to the right.

If the display doesn't work impeccably now there is a fault on the displays board. The following flowchart will help you to find the failure.