elec mech to my rescue ....
When I remove the 24V ground wire from the circuit and touch it to each individual segment (after the 2804), all 3 corresponding segments come on - touch seg. a - all 3 a's light up., etc ...
Thanks again for jumping in to offfer help ...
I will have to have some guidance on measuring the current. I def. do not want to short something out! I also noted some of the measurement you had posted when using the same displays, but the power supply may have been different in your case.I think your power supply is a bit low. Assume worst case scenario, all segments lit, 7 segments x (let's say) 20mA x 3 digits = 420mA. Now, I could be off on this as the datasheet seems to infer each strand of LEDs takes 25mA, but each segment would then consume 50mA. If this is correct, then we're talking 7 x 40mA x 3 = 840mA. I'm hoping Bill will chime in with his thoughts regarding what the true current per segment should be.
When connected to the circuit, all 3 displays appear off (possibly extremely dim, but to the eye they appear off. I have the 24V supply hooked up at the 3 2907's and the ground connected to the 9V supply ground.So, what exactly is happening when you connect the 5" displays to your circuit? Are they dim? Are only certain segments lighting up? Are certain segments brighter than others? Do all the digits appear to be off?
When I remove the 24V ground wire from the circuit and touch it to each individual segment (after the 2804), all 3 corresponding segments come on - touch seg. a - all 3 a's light up., etc ...
I will check voltages, but as I mentioned above, I will need some help on the proper way to measure the current.What is the voltage across the C.A. pin and one of the segment inputs when your circuit is on? Do this for several segments and for all digits.
What is the current going into each segment? Same as before, please do this for multiple segments for each digit. Let us know if you're unsure how to do this with your meter and I'll explain. If there is any doubt, please ask first because it is possible to short something out if this is done wrong.
Thanks again for jumping in to offfer help ...