Some segments are missing in the digits

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ome segments are missing in the digits. Every PinLED Digit has 16 segments. These segments make it possible to show letters and numbers. If the upper segment in the digit is missing the upper or lower row displays an "H" instead of an "A". This means an "A" becomes an "H". The pinball CPU board is relevant for the controlling of the different segments. PIA U41 with the ports A and B controls the upper display row (segments "a" to "com"). PIA 42 with port A and PIA 51 with port B controls the lower display row ( segments "a" to "com"). If a failure occurs, i.e. one segment is missing, the fault will be present on all 16 digits. If a segment of one digit is missing the PinLED digit is defective. 

The following flowchart will help you to find the failure. It contains the information which IC's will work for each segment.