A bad transistor.

Flashers are driven by solenoid drivers. Inside page of your manual. Get from ipdb.org if you don't have one.

Info in the chart attached from the manual, does not seem to be 100% correct in terms of # of flashers involved since it says flasher 10 is 2 backbox and 1 playfield.

The Flasher 7 is on the C side so maybe your a/c relay isn't working properly, if 7 is still an issue. Don't remember which flashers were removed on F-14 at least in terms of their #'s.

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Were these flashers working before and then failed?...or have they never worked? (depending on answer, a different course of troubleshooting)
Just to make sure, since it wasn't mentioned - both bulbs are the correct #89's? You said they were dim, usually when the driver transistor fail they fail completely dead...only very occasionally they fail partially.

slochar - keep in mind that there is only one A/C relay, and if the AC relay is bad it will affect all of the switched coils & flashers, not just one.

I suppose I should have read his initial post better since he says all the other flashers work. I read the message yesterday on my phone and replied today when I could highlight/paste the page in so bad for me.

And boo to data east for making the default a/c side the flashers! Duh. Feel like that's always appropriate to mention whenever a/c side stuff comes up.

So if you were to ground the metal tab of Q-14 with a jumper connected to the ground braid, does the flashers light now?

No big.

Maybe?

This is a correct part.

???

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I would use a logic probe or DMM and test the output of U-17 pin 8. In attract mode pin 8 should be a low/0.8 volts.

Flasher #7 may not be implemented in software. I would take some measurements before bothering to install any parts or make any mods.

Flasher #7 is implemented in software, it only doesn't operate because the circuit & bulb hardware is removed. It can be restored by reversing the steps of the original mod to remove it. There's a helpful video at the link below.
https://www.ipdb.org/files/804/Williams_1987_F_14_Tomcat_Service_Bulletin_41.pdf

Send me your email and I'll can send you the PDF file that I have to make the necessary changes. It will be Monday before I can send it. I will out of town this weekend.

F-14 Tomcat Retrofittinig the Proto-Flasher.pdf

OH! The PDF does work if you click on it.

This seem normal, now check SR5 pin 9 in attract mode. Should be 0.0 volts.

Correct the white dot is pin #1.

This would indicate that Q-10 is still good. So this just leaves Q-14. Now the question remains why Q-14 went bad? Are you running standard #89 bulbs or leds? After replacing Q-14 I think I would do a current test manually on this circuit before turning on Q-14. This can be done by using your DMM in series with this circuit. Set DMM to DC current, move red lead connection to correct spot, hook black lead under ground braid, turn on game, then touch red lead to Q-14 metal tab. Read meter and disconnect red lead. What do you get?

Existing Q-14 with #89 bulbs. Connected red lead of dmm to 10A port. Set dial to 10A. Touching metal tab of Q-14 reads .73 in both flasher test mode and in "on".

That seems fine too. Maybe you just got a bad TIP 102. It happens.

Could a loose bulb socket cause these issues? I noticed the one spins a bit on the backboard and I had to hold it from the back to get the bulb to lock in.

The wire solder tabs can sometimes spin around and touch each other, this will be a short circuit. If this happens it will pop the transistor the first time it turns on. You may have inadvertently spun the wire tabs apart when you changed the bulb removing the short, but the TIP was already damaged. This is something I always check when I bring home a new game for the first time.

No, the whole idea of the warming resistors is to pass a small current through the lamps while they are idling. If the resistors were failing 'high resistance' (which is by far the most common failure mode of resistors) you wouldn't see ANY glow.

Because you CAN see a glow I would say they are doing the job perfectly!

Is there any alkaline damage to CPU board?

Well as SRC-6 goes, that was a very good temporary repair. I don't think that this is the cause of your flasher issue, but you never know. Either you have a part that is randomly acting up (U-17) which is smoking the driver transistor or maybe this Hack is causing erratic switch closures causing the driver transistor to lock on. Replacing SRC-6 with a non capacitor resistor pack is well documented on System 11s. Try that with a new TIP102 and retest.

Please keep your terminology correct to avoid misunderstandings.

There is NO ACID on the main board. Any leakage is from ALKALINE batteries (usually) and alkaline is the exact opposite of acid.

Come on I think everyone knows what he meant.

Yes, they probably did but if one incorrect thing is "OK" then I could start calling resistors, capacitors and triacs, transistors - you know what I mean....

Let's try and keep the correct terminology to avoid misunderstandings - PARTICULARLY important when people who are unfamiliar with electronics are attempting to repair something WAY beyond their skill level!

Let's face it, many asking for help here have trouble knowing which end of a soldering iron to hold let alone make a sound solder joint without destroying the board!

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No problem, as long as he replaces all of the SCR's then checks the value of all the connecting wires (should read about 127 microbreweries each) then we are good to go.

Isn't it better to try and educate people rather than allow them to continue down an incorrect path? One small mistake leads to bigger and bigger misunderstandings.

Since you know SRC-6 is bad, then replacing this first might be the way to go for now. I would purchase some AND gates just to have on hand anyway. Also some chip sockets too.

Google is your friend:
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There are many TTL logic gates used on the CPU board. U-17 in the circuit you are working on is an AND gate. It has a part # 7408 under the label.

https://www.marcospecialties.com/pinball-parts/7408

https://www.greatplainselectronics.com/proddetail.asp?prod=7408

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There are literally hundreds of thousands of ICs and they all do different things. The term "IC is just generic for a small package of micro electronics it doesn't describe the function of the device where saying it is an "AND gate" does.

The 4 flashers in the backbox, alternate back and forth in pairs during the game and at the end of the game.

You either have alkaline damage or you have bad game rom sockets. If your board looks good maybe you should change sockets if your able.

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I have seen this before, but not very common. The flashers could also be part of the erratic behavior.

Sounds like garbage on the data or address bus. An easier solution before you pull out the soldering iron again. Is to either replace the CPUs (the chips themselves not the board) with known good ones, or use a logic probe to poke around the pins to see if any critical ones aren't strobing. Preferably the logic probe first along with voltage checks with a meter to make sure nothings wrong that's going to also destroy your good CPUs. It could be a PIA too, which you can also do the same procedure too. But really once you start getting this deep, unless you really know what you're doing, it's probably best to just buy a new after market board.

I understand that something on the play field could be miss wired/shorted and be causing damage to Q-14, but this can't set off random sounds. Now if U-10 was to be acting up it could set off some coils( solenoids 9-16) and some sounds. But bad sockets on the CPU chips could cause this also. U-10 isn't socketed from the factory so you can't swap in a different one for easy testing. Williams did use cheap sockets that are @ 35 years old now. I can't tell you which is the best direction to go, from my couch. But you know what your options are.