I am stumped!

I have an F14 with the right slingshot fires upon power up.
I have replaced the tip-122 and the 2N4401 as well as the resistor network
I checked and replaced U45 and U50 and both had bad pins that were associated with Q 71 and Q 77

Is there anything that I am missing?

Are there any components behind the U45?

I also tried to isolate the problem by only attaching the power input and 1J19 but still get the sling firing upon power up.
I replaced the coil as well and the diode on the coil is good.

Seriously ready to throw in the towel!

Thanks in advance!

It locks on, yes.

I just found that too. I looked on page 28 and see that the 7407 is in front of everything. The slingshot switches are not "in the circuit" as I am only plugging in the connector for the special solenoids. I am leaning towards a bad pin on the 7407. Just not sure if I have one to replace it.

Thanks!

7407 checks good... Now I am at a loss!

Yes, TIP and 2N4401 test good as do all components in the circuit.
Yes, there are no switches shorting and as well only the power connector and the connector to the special solnoids are connected when power is turned on.
No solder blobs or coils shorting. Although this particular coil when I got this game was put in incorrectly and the diode was shorting on the bracket.
I have since fixed it, replaced the coil and put back correctly.

To summarize:

Everything within the circuit checks and tests good from the 7407 to the U45 and out to the 2N4401 and TIP 122.

I guess the only thing left is the actual slingshot itself. Maybe I should try a different coil perhaps when powers on it ground itself out? (hands in air)

I just moved the wire from the cpu j19 pin 4 (I think thats Q71) from right slingshot
to the left slingshot (cut wire at left slingshot) powered up and coil locks on. This removes the right sling coil as a possible problem.

I see that Q73 is not currently being used. I may try rewiring everything to that transistor circuit and see if that will solve the problem.
At this point, I have tried everything I can think of

No stuck switches. Switch matrix not connected.
I did check ZR1 and ZR3 both check good.
I have been through the entire circuit. I have replaced the tip 122 and 2n4401 as well as u45 and u 50 (7402) i checked the 7407 pia. good. This is a massive mystery to me! I have been repairing pins almost 30 years, never seen anything like this!

Ok, I will disconnect the coil grounding and check the path. From the schematic though on page 28, it starts at a 7407 and runs through to a u45 and u50. From there it goes out to the 2n4401 and tip 122 as well the resistor network. All has been replaced except for the 7407 which I did find to be good. Although, I did check the 7407 with game off and not with a load on it Hmm, possibly with a load on it could bring it down. Thanks!

Actually, I have tried all connectors removed except power. With J19 connected, the coil pulls in immediately upon power up with only the power and J19 connected. So, I would have to try this with only the power input going to the board and J19 removed. Hope this works.

Huge thank you to everyone that wrote in to help. SUPER APPRECIATED!!! Problem solved!

So, here is the answer: Ready????

So, U45 pin 4 was not making any continuity to the middle leg of the 2n4401 causing the transistor to always short to ground and
thus pull in the coil as soon as power was aplied

Thanks again!.

With power on and j19 disconnected. I metered the tab of q 77 and compared the other tip 122 and found q 77 had .600 while the others measured 0.00.
I followed that signal back through the circuit and found no continuity from pin 4 u45 to the middle leg of 2n4401. Problem solved