So I made a post about this before, but I've had a version 3 DE CPU sitting around forever, which works fine except that many of the special/reflexive solonoids are locked on. I've tracked this back to the EN Blanking line. It's only about 1 volt.

The 12F (marked 12 E in some schematics) 7406 chip is getting 80mv on pin 1, and putting out only that 1.0v on pin 2. I can't figure out why. This makes the signal too low for the 7402 to recognize, so it puts out high on the signal line, activating all the transistors. I've replaced the 7406 twice (admittedly with 74LS06 chips, but that shouldn't make a difference) and it just keeps on doing it. I'm thinking there has to be something oscillating on the line, but I've replaced every IC that circuit touches except the 11B 6821, which only outputs the LED line. The datasheet says the 7406s are just inverters, and it's got 5 volts on it's VCC. What am I missing?

Also, the two solonoids controlled by B12 are fine. B12 gets the same low voltage as A12, but seems to not put out the related high signal.

Wow. Cool. I'll go replace those then. So...how do they get the 5 volts normally? There's no resistors between the 7406 and the 7402 chips. Can they be pulled up anywhere on the circuit as long as it's after the output?

Oh, duh, there are resistors. There's a whole bank at R24.