Ready to Power up the 11/04

The insight came when I looked at which keys on the number pad worked and which didn't. I came up with the following table Pressed = Displayed 1 = 1 2 = 0 3 = 1 4 = 4 5 = 5 6 = 4 7 = 5 0 = 0 If you convert this to binary it becomes pretty obvious where the problem lies. The invalid display is for the items marked with * and all have the second bit set. If you mask out the second bit you get the displayed value. 0 = 0000 1 = 0001 2 = 0010 * 3 = 0011 * 4 = 0100 5 = 0101 6 = 0110 * 7 = 0111 * The front panel uses a 7447 BCD to 7 Segment decoder to drive the LED modules. If pin 1 (B) on this is not being set when required then the behaviour will be what I am seeing..... it isn't that the keypad is getting it wrong... but the display is showing the wrong value due to a missing bit. Need to do a bit more digging here but given that this line is pulled to +5V via a resistor on the front panel board I am hoping that the problem is either a connection problem on the front panel board with the line not being pulled up or the 7447 needs to be replaced. If there was a break in the ribbon table to the controller board then the bit would always be set and a different set of incorrect values would be displayed. Hopefully there isn't a fault on the controller board that is pulling the pin to ground.