I am going through a Road Kings that I got in unknown condition. The displays are out and I'm waiting for parts to rebuild the high voltage supply, but that's another story.

Regardless of the displays it boots and I can start a game, but none of the special solenoids work (all 4 pop bumpers and 2 slingshots). the special solenoid fuse is good, and I get 25v at the fuse. Also the flippers work before starting a game even.

I haven't dug into this too much yet, but any insight that might save me time is greatly appreciated!

If i ground out the tabs on each of the driver transistors the coils fire, so the power to transistor chains are okay

I guess I might as well get a logic probe and learn how to use it. Just digesting the schematic but im a little new to this. Looks like the special solenoids and flippers are split up between two 7402 chips, I cant see where the path goes from there because the schematic I have is missing a page (its split up into 4 diagrams and I only have 3..) can anyone help with a complete schematic?

the ipdb schematic is what I have and out of 4 pages for the cpu schematic it only has page 1, 3, and 4, with page 2 left out. Id be grateful to anyone who can help me out with the missing diagram.

i took btw75's advice and looked up another sys 11 on ipdb and found the full diagram, so dont go to the trouble. thanks!

After going on a month long motorcycle trip I am digging back into this problem. I checked the logic paths with my DMM and I suspect that U50 is bad. Ill post the schematic here, so maybe if somebody with more experience working on boards can pipe in and let me know if im on the right track or not..

Looking at the logic gate on pins 11, 12, and 13 on U50, as I understand it only when both inputs go LOW will the output go HIGH. When I start a game 11, and 12 go low which, based on my understanding of this schematic, should cause 13 to go high. However pin 13 remains low, going through an inverter (U56) and holding pins on the rest of the NOR gates high so the special solenoids will never energize. If it were working properly and pin 13 were going HIGH and then inverting to LOW pulling one side of each logic gate LOW, and I presume that the other leg of the gate would go LOW when the switch is closed, so that the two lows would give a HIGH output and fire the solenoid. so it seems that the output at pin 13 of U50 should switch when a game is started, enabling both the flippers and special solenoids.

But my flippers are always on, the flipper relay closing as soon as the machine is powered on. Q67 tests okay, and with the game on I'm not getting 5v at the collector, so I think the relay coil must have a path to ground somewhere else. The diode right there is shorted, and some of the resistors measure lower then they should (although I'm not sure if measuring them as part of a circuit will give a proper reading anyways).

I think I understand the issue with the special solenoids, but just don't understand why the flipper relay is being closed.

special solenoids schematic.jpg

I get about 120 ohms

Ive got a 1978 Honda Goldwing. Had a great trip! Along the way I was able to stop at the Seattle Pinball Museum, Las Vegas Pinball hall of fame, and also a pretty decent little pinball arcade in Fargo, ND. Plus alot of great scenery along the way!

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U50 Pin10 stays low but the flipper relay still energizes. ive got parts coming from digikey, got two 7402s just incase (U45 is already socketed), a replacement diode and some 10k resisters, and ive got some pre driver transistors around. Parts should get here today or tomorrow and Ill do some more poking around once ive got the board on the bench. thanks everyone

okay, so I got the parts, replaced U50, and the diode, resisters, and transistor close to the relay. Special solenoids work now! wooo! and the flippers dont activate until I start a game! yay! and i have no sound... WTF?!?

so ya, now no sound during the game, in sound test diagnostic, or when pushing the sound test button on the main board. man, what the hell.

sound worked fine before

also, in an odd twist the flippers and special solenoids are active during diagnostic tests. is that normal?

oh, yah, hehe. I had J15 and J16 mixed up. both 4 pin connectors next to eachother. One goes to the music board and one to the speaker.