Hi everyone. I’m having an issue on my F14 Tomcat where, during gameplay, switch 55 (General Yakov) and sometimes (not as often as switch 55) also switch 47 are being triggered just by hitting the left flipper, switch 63. During gameplay, it happens very often. Sometimes every time you hit the left flipper. In test mode, it doesn’t happen at all for some reason. Ive tried for days to get it to happen in test mode. All three switches are on the same row in the matrix.

I originally suspected an incorrectly gapped switch that was making intermittent contact from vibration. I pulled switch 55 off of the bottom of the table and gapped it properly. The problem remains. I even disassembled the switch stack. There was absolutely no way that the switch could be making contact.

Even with the switch hanging from the table with an inch between the blades, the problem persists. Like I said above, in test mode, it doesn’t show that any other switches are being activated. I’ve tried test 5, switch levels, and test 6, switch edges. Once you start a game, it’s immediately obvious that something isn’t right. The first four or five times I hit the left flipper, it starts scoring points as if those other switches are being closed too. The sounds are activated and in the case of switch 55 for Gen Yakov, the kicker solenoid is activated too. After the first four or five flipper strokes, it happens every handful of times the flipper button is pressed. It seems to be connected to the lower flipper, not the upper flipper. If I push the flipper button gently enough to activate the lower flipper but not the upper flipper, the problem happens. If I hold the left flipper button in and let it out slowly so that the upper flipper is cycled but the lower flipper is held, the problem doesn’t happen.

I have a logic probe, a DMM, and a small o-scope. I tried looking at voltage through connector 1J8 pins 7, 8 and 9 with my meter. Pin 9 is the column with the left flipper. Pin 8 is for the column with the Gen Yakov switch. With my meter on C53 in the flipper circuit, the voltage is steady when the flipper activates and the General Yakov switch doesn’t. When the flipper is pushed and the general also activates, the voltage on the flipper circuit jumps a bit and then settles down after the General Yakov sounds are done playing. It does this when the general switch is physically closed and also when the intermittent issue is happening. I’m not near the machine right now so I can’t give any specific voltage numbers off the top of my head. I also tried my logic probe on U38 and U40 to see if I could see anything going high when it wasn’t supposed to. Unfortunately, every pin I checked stayed low while cycling the left flipper.

The fact that this is so intermittent is my issue. If it was a mechanical issue or a shorted transistor, I could find it and fix it.

I don’t think this is related to switches or the harness but I’m going to build a switch matrix tester to rule those out.

Do any of you have any other ideas? Ive attached a pic of the MPU schematic I’m working with and a link to the manual.

https://www.ipdb.org/files/804/Williams_1987_F_14_Tomcat_Schematic_Diagrams_manual_pages_51a_to_60a.pdf

56EE4BDE-394E-430D-9E49-BCF334053446 (resized).png

I’m not sure what you mean by “lane change switch”. I went through every switch in test mode and made sure I found every one listed on the matrix chart. I checked the diode on switch 55 but no others. I will check the others in that row and those columns this afternoon.

Thank you.

Thank you. I will check the diodes this afternoon. I appreciate your help.

Well I’m unable to find any loose diodes on any switches from those three columns. I did find a broken 2.2k 250vdc capacitor on the left flipper. It looks like it’s just to limit the spark on the EOS switch. Hitting the table doesn’t ever activate the switches. It only happens when the game is in play and you hit the flipper button.

Is it possible that the PIA has an intermittent short internally?

Thank you. The right flipper scores no points when holding it up with my hand and hitting the button or when I hit the right flipper button any time. The left flipper button does NOT score any points at all when holding the flipper up with my hand and pushing the button. As soon as I let it go and the coil takes over it starts scoring points almost immediately.

I just found the flipper section on the schematic. I’m going to look it over and see if I can come up with anything else to check out.

Thanks again.

With the flipper held up with my hand and the flipper button pressed, the flipper holds firm when I let the flipper go but hold the button and scores NO points. If I let the button go and hit it again without holding the flipper, it scores 50,000 points when switch 55 is triggered and 1000 points when switch 47 is triggered. It doesn’t score points every time, but it happens more often than it doesn't.

Yes, switch 55 and 47. 55 is the problem most of the time. The ghost scoring happens even with that switch hanging from the bottom of the table with the stack disassembled and the blades an inch apart or with a piece of tape in the switch.

Yes, checked all diodes on every switch in those columns and that row.

It turns out switch 31 is also ghost scoring. It’s a micro switch rather than a stack of leaves. I attached a picture of it. I don’t see a diode on that switch but I don’t see one on any of those three switches and the other two aren’t ghost scoring. All of the ghosting switches are on the same row.

So far, the only thing I’ve found out of sorts is that 2.2k 250vdc capacitor on the left flipper.

image (resized).jpg

Yes, I checked them both.

Also, I pulled the green-violet wire out of the connector. This is for the column that switch 55 is connected to. It still scores switch 55 when it’s not even plugged into the board.

I haven’t checked those. I will next.

Last night I pulled the green/violet wire out of the connector on the board. This is the wire for the column that includes switch 55. Even with switch 55 disconnected from the board it’s still scores points when you hit the flipper.

No, I said the capacitor on the left flipper has a broken lead. I haven’t found anything that’s fried.

I can’t find anything else anywhere that seems to be wrong. Not sure what else to check at this point. Nothing seems to be out of sorts.

Thanks for that info. I will check them and report back.

I checked all of the capacitors for each column. They all checked out nearly identical.

I turned the machine on, started a game, and unplugged 1J8 from the board. With every one of the columns disconnected, the ghost scoring still happens when the left flipper is actuated.

With 1J10 and 1J8 both disconnected, it doesn’t ghost score at all. With 1J8 disconnected and 1J10 still connected it ghost scores. With 1J10 disconnected and 1J8 connected, it doesn’t.

I got around to checking the diodes on the flipper coil. They both test good.

Thanks. I already checked all of the SR’s and SRC’s in that circuit. They all test good and don’t look to be damaged.

I appreciate you guys taking the time to try to help me.

Thanks for that info!! I will look into it and report back.