All special solenoids( controlled by K1 relay) are live/grounded between games. I guess the K1 controls the ground and allows all the switches to fire those non MPU controlled coils. From my internet searches I've gleaned that this relay is supposed to shut off at game over. If this is correct what is allowing the K1 to stay activated and whats a good way to test.

Thanks for the assistance as I muddle through my learning curve.

Thanks for reply. I have seen this schematic in my downloaded manual, and can understand and recognize some of the components and purposes. Direction of data/power still confuses me. I think I understand that the chips handles data signals to the work horse components(transistors and the like.)

All my pops, slings and flippers can be fired via pf switches between games w machine powered on. Since these appear to be all the special solenoids and after reading a bit (see below,) I concluded(erroneously?) that K1 controls all special solenoids grounds. Attached are two of my source pages from WMS trouble shooting guide for Sys 9. They are pages 36 and 37 not as I labelled.

Give me a little info and I'm dangerous, but at least I try and test first. I do have a logic probe, and a multi m as well.

pg 37 Sys 9.pdf

pg 38 Sys 9.pdf

Not sure what between PIA and U58 means. I found both U58 and U59 on the board, and I'm assuming one side is inputs and other is outputs, so I can check the pins hi/low status during game and not. Also I can check U4-19, U6-13 and U58-6 per instruction.

I connected tester leads to TP 1&2 for 5v and gnd, and figured I should use the TTL setting. hopefully that was right, it was same setting i've used before checking chips. Results were U4-19: in L ,out H, U58-6: L and L, U6-13 L and L. I also decided to check some of the other pins on the specified chips and was getting some square pulse readings that I've never seen before. Most of the rt side 21-36 of U4 and a lot on both sides of U58. Is that significant?
Also, when machine is first turned on the 3 pops fire in quick sequence. I don't have another Sys 9 so don't know if it's normal.

Thanks again for direction

in= in game, out =out of game(attract mode) L = low, H= high for logic probe reading
Square pulse indicated by both high and low lit with pulse light lit also

I just double checked w PF up, and it appears all but flippers, kick out coil, drop target reset coil fire on power up. I have seen machines do a reset at game start up, clearing any stray balls etc.. but I don't recall on power up.

Forgive my curiosity., Does that mean all sq pulses are inconsequential? U6 is the only chip that didn't have them. The little ICs are pretty cheap and fairly easy to replace, so I'm cool with that. U4 is another animal.

Additionally, could this be related to the coils firing on power up? Note: Per quick investigations, it appears that it is not unusual for this to happen on start up, tho I'm reluctant to write it off as we're working in that neck of the woods.

Thanks, I kinda understand My confusion goes back to the direction of data and current flows in these schematics so.... I plod on slowly in my learning curve.

Ok, So I'm going to replace U6 and likely U58 while i'm getting dirty. Hopefully, i have thoseand the sockets or it's another GPE order.

Thanks again, I'll respond as I move forward.

Ok, I found that I have some ICs that may work. U6 calls for a 7402, I have 74LS02. U58 calls for a 7406, I have a SN7406N.

Can I use these as replacements?

Thx.

Ok, I found this while searching the internet for substitute for 7402 and it's a Pinside post from Ed at GPE.

I guess I get me a plain old 7402. Will report back upon installation.

Well finally back with an update. I took some time off from this conundrum to let my sanity recharge. After finally ordering up the parts from GPE ...and waiting for delivery, I popped the new ones, LS7402 and 7406N into the new sockets I had perviously installed. Initially, there was nothing at all going on in the Solenoids circuit. So I immediately checked the fuses and two were blown, F1(high voltage) and F2(solenoids), tho not sure what happened there, but something did! Anyway, I replaced them both and fired it up, but no special solenoids at all. Worse off than before as they were were working all the time prior. So I swapped out each U6 and U58 to see if maybe I got a bad one and no change. Last thing I did was check the pins with the logic probe. U4 out of game High, and in game Low. U6 out=L, and in = L, U58 out=H, out=H.

At this point I walked away for a while to gather myself(sorta.)

Now, clearerish headed , I'm trying to figure how I went backwards in this repair. Please Save me from myself...and this machine!

oops, same ones as before, U6-13, U58-6, U4-19

Ok, U6- 11 out=H, in=L
U6-12 out=H, in= H

Well Thank You'z, that's a whole lot of info guys. I'll read it at least 3 more times, to make sure I get my head good and spinnee. Then, I'll test all mentioned U pins in attract and game, and report back.

For what it's worth here are the latest results,
U59-8 Out of game= H and In Game = H (problem..?)
U59-9 Out =H and In = H

U6-11 Out = H and In = L
U6-12 Out =H and In = H

Additionally: Upon game power up saucer ejects fire and upon game start ball trough eject fires(normal actions I think.)

Lastly and maybe irrelevant, During attract all lamps either on or slow flashing depending on which lamps, but on game start there are a ton of lamps staying on. I don't remember this occurring in my original assessment but it has been a couple weeks of hiatus(?). Some obviously should not be on, others I'm not so sure (literally more than half of the lamp matrix ) I mention this not to muddy the thread but as a possible correlated issue or?

I'm getting ready to pull the board again, and recheck continuity/traces but part of me says waste of time. If I'm getting signals/pulses/blanking to the various U pins, I've got my continuity, correct?

Thanks for the continued lessons/help!

So......replacing U59 is the next step?

Ok...., I'm tip toeing around as it appears the replacement of U56 has solved the final leg of special solenoid issue! Everything comes on when it should and shuts off as well. And as a a side Bonus.....the lamp issue is gone! I can only guess I may have had a connector askew as nothing but U56 and connectors were touched.

All in all, I learned some more and really appreciate the help and patience.

Cheers,
Larry