Hi, I'm the guy making these kits. Thanks for the great write-up! I'm relatively new to pinball but I'm an engineer who has been doing design for more than 35 years. This board design came out of my own experience restoring machines and being shocked at the cost to replace dead displays.

The ICs themselves are CMOS so they draw negligible current. The 7-segment LEDs draw 20 mA per segment when on. The Bally pinball machine design has multiplexed displays, i.e. only one digit per display is actually on at any instant in time. So if every digit is showing an '8' (all segments lit) the display should draw about 140 mA. I would figure about 145 mA worst case when accounting for all other loads on the board. If some segments or digits are not lit the current draw will drop proportionately. (e.g. 1 digit showing an '8' = 25 mA, 6 digits showing a '1' = 42 mA )

Absolute worst case: If all 5 displays are on and every digit is showing an '8' they could draw as much as 725 mA total.

I have not tried measuring the actually current draw on the 5V supply. The schematics I have looked at imply that at least 3 different types of voltage regulators were used: LM323K, LAS1405 and 78H05. The 78H05 is rated at 5A and the other two at 3A continuous (and in my experience usually work well beyond the rating). All three have over current and over temperature protection so they should not be damaged if the load ever gets too high. The transformer is actually fused at 4A.

Without actually measuring the boards, it looks like the solenoid driver board is the biggest 5V power hog. Each driver channel looks to draw about 40 mA so about 800 mA. The CPU board about 500 mA, the lamp board a few hundred mA and the sound board less than 100 mA. So my guess would be about 1.6 - 2.0 A on the 5V supply not including the displays. Again, that's just my estimate looking at the schematics.

The inline resistors on the data lines don't actually change the current. They are there mostly for protection from being plugged in with power on and electrical noise. The voltage drop on LEDs is usually a function of the color. If Rottendog is using orange LEDs with 100 ohm resistors, they are probably also drawing about 20 mA per segment.

BY the way, I have been considering selling a 7 digit version of the display kit but sourcing LEDs with the comma is a problem unless I want to go semi-custom from China. Wondering whether people would be interested in a display that only had a decimal point instead of the comma?