Checking 7-Segment Display


#1

When checking 7-Segment Displays , all you need is one simple tool - your Multimeter. The below steps may help you test a 7-Segment Display.

  1. Hold the display in your hand and identify pin 1.
  2. Now take the multimeter (assuming a red lead for positive and a black lead for negative) and set it to the proper continuity range.
  3. Check your meter with a sound test (touch both the leads together, and a sound will be produced). Sometimes the battery in your multimeter may grow weak and it will not be able to display data properly If this happens switch out the batteries in your multimeter for new ones.
  4. Put your multimeter’s black lead on pin 3 or 8. Both are common pin as they are internally connected.
  5. Now put your meter’s red lead on any other pin such as 1 or 5.
  6. If any of the display’s segments glow then the display is common cathode.
  7. If none of the segment glows than interchange the leads of multi-meter.
  8. Connect your meter’s red lead to pin 3 or pin 8.
  9. Now put the black lead of the multimeter on other remaining pin. If any of the segment glow than the display is common anode, as in common anode the positive pin is common and the rest are connected to a negative supply.
  10. Check all segments of both common cathode and anode to ensure the display is working properly.
  11. If no segment glows, this 7 segment is faulty.

#2

I just wanted to share a test i did on a customer display. Looking at part 67-1469-ND there was a thought that Segment A and F in Digit 1 were bad.To do the test I needed to identify two aspects. First I need to know if the part is a common anode or common cathode display. Then secondly I need to identify which pins activate segment A and F.

Looking at the data sheet I can identify both in the lower right-hand corner. This is a Common Anode display and with the Anode for Digit 1 being Pin 14 and the Cathode for segment A being Pin 16 and segment F being pin 18.
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Knowing the configuration of the display I was able to set my meter to the diode checker and place the Red (positive) lead on Pin 14 and the Black lead (neg) on the Pin 16 and 18 respectively. As you can see both segments worked in the test. With this knowledge we were then able to narrow down the issue in the circuit.

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