| Sympton | Cause | Procedure |
| A) None of the numbers of the displays turns on | a) Supply failure | Test with the voltimeter the voltage at the input
connector, which has to be 10 VDC +- 1,5V. |
| | b) Shorted or open 10V line | Localize failure in decoder module. Carry out a
visual inspection for shorts. When found replace fuses in decoder module. |
| | ) Information superior to 9 in line L1 to L8 | With the test point check in which line TL turns on. Verify with coding table and see which lines are connected to positive. Look for possible failure in decoder module. |
| B) A pair of numbers count even if it does not have to do so. | a) J control input is 0 | Test with the test point that in input J, TL does
not turn on. Look for failure in decoder module. |
| C) The unities hundreds and tenthousands do not count correctly. | a) One of the inputs L1, L2,L3,L4 is always 0 | With test point on L1,L2,L3, and L4, TL has to blink. If not turning on, look for shorts or failure in de coder module. |
| | b) One of the inputs L1,L2,L3,L4 is always 1 | With test point on L1,L2,L3 and L4, TL will be continously on. Look for shorts of failure in decoder module. |
| D) The tenths, thousands and hundredthousands do not count correctly | a) One of the inputs L5, L6,L7,L8 is always 0 | With test point on L5,L6,L7 and L8, TL has to blink. If not turning on, look for shorts or failure in decoder module. With the test point on these inputs TL will be conti-nously on. Look for shorts or failure in decoder module. |
| | ) One of the inputs L5, L6,L7,L8 is always 1 | |
| E) A number of the display does not operate correctly. | a) Integrated circuit 4511 is damaged | Setting the test program on input D of the IC, TL has to turn on. When testing the outputs, (a,b,c, d, e, f ,g, ) TL has to be on in any case. If not, replace integrated circuit. |
| | b) Damaged number | Proceed with the same test as in point a). In this case we will see that, when checking the outputs, TL will be always on. Replace in this case, the pair of numbers. |
| F) The display shows the score of a player different from the one, who is playing. | a) Command impulses are not received at input J. | With the test point on the J input of the player whose score is wrong displayed, TL will be always off. Look for possible shorts or failure in decoder module. |
| G) A pair of numbers do not count correctly | a) Command input J does not become 0 | Since 0 commands are very quick, it is impossible to test them with TL, or with a normal voltimeter. For checking we will make a bridge from J input to negative If the pair counts, the displays board is correct. In that case look for failure in decoder module. |
When the control signal becomes 1, the information in the output remains memorized. That means, if we
change the inputs, the output will not change.
