My #Judge Dredd has one last problem I think I need to fix before it's playable. Any time a 50v solenoid fires, the 12v solenoids ( not solenoids but really motors to the planet and crane ) bump just a little bit. What is very strange is that this happens even when the coin door is opened and the 50v solenoids don't actually trigger. All my power driver board's test points are at the right voltage. There's 74v at the coil solenoids. I thought it might be something leaking from the 50v line to the 12v line but when the door is open that should cut the 50v line and prevent anything leaking.

All my switches and opto's test out okay.

When this is the most annoying is when the five drop targets fall and they need to be popped up. The solenoid coil fires to reset them but it's usually too weak and that drop target module goes into a machine gun mode trying to get the targets up. This then makes the planet and crane move at almost normal speed. I wonder if I should disconnect the crane and planet motors to see if the drop target coil get's more power if they are disconnected.

I can link to a video of it happening on YouTube if that helps.

I have a new sleeve and coil. From Marco. 100% matched up. Right Ohms, etc. The drop targets do get reset in Test Mode usually.

"Chip starting to fail" A LS374 or Transistor? Where should I look? I had my power driver board out recently and checked all the transistors. Had two that needed replacing. I haven't checked, nor do I know how, to check the DIPs 374s.

Pin 15 does not go low when the drop target solenoid fires. Pin 6 does. Planet turns 1/16 of a turn ( or so ). Seems to indicate the CPU and logic gates are good. Must be a bad ground somewhere or Q64. Any tips for finding a bad ground?

Took the Driver board off, checked every transistor on the solenoid column, every diode, every resistor. Everything checked out fine. Put board back in same issue. Had a v6 ROM in my spare parts collection, tried that same issue so I put the v7 ROM back in. Issue still persists. Pulled the connector at J118 and the planet moving when bumping 50v solenoids went away ( also the motor or arm doesn't turn but that's okay for testing ).

So I think this eliminates the possibility of something under the board being shorted or loose.

Also that was my last idea and now I'm stuck again.

Checked both motor EMI boards. Diodes are fine .5v one way, 0v the other. all inductors showing .4 ohms. I think that's okay. They aren't shorted or disconnected in any way. I've been wasting so much time with this to no resolution. While I love troubleshooting I love fixing things even more.

Maybe I should just buy a Rottendog power driver board and be done with it? I wish I could rent a known good power driver board before buying one.

"If an inductor is reading very, very small resistance, less than an ohm (very close to 0Ω), this may be a sign that it's shorted. Functional inductors normally read a few ohms, greater than 1Ω and normally less than 10Ω. This is a healthy range for an inductance value. Outside this range and this is normally a sign the inductor is bad."

Maybe I'm wrong. Just googled testing an inductor and found the above. I'm pretty sure I was reading .5ohm, maybe that's too low.

Repairing that wouldn't be a problem. Where would you suggest I cut these lines?

I made a jig that skips the motor and arm pins on J127. The motor and arm don't turn as expected. I have no other choice than to believe it's on the driver board. With the arm and motor disconnected I still can't play though so it's not the arm or motor that's messing up power either. In test mode ( with those pins disconnected ) the drop target reset is strong and pops the drop targets right up, but during play it's weak and does the rapid fire ( even without the globe and arm moving ). Something else is messed up with the driver board. I can't find any bad transistors, diodes or resistors. The logic coming in seems fine with the logic probe. The voltages are at the correct levels at the test points.

If there is anyone in NE DFW that can loan me a driver board I'd appreciate it

Guess I should just go buy that rottendog board and stop wasting my time.

I'm going to go home tonight and clean all my opto's. They all test fine but maybe with a load something bad happens.

Finally bit the bullet and bought a RottenDog power driver board. Game plays like a charm now. I wish I could have found the problem on the original board but I didn't want to have the game sitting NOP any longer. Thanks for everyone's help. Maybe one day I'll try to solve the original's problem.