After installing the cointaker color changing door mod, I started to notice after a few games, that the upper left flipper was firing a millisecond slower and out of sync than before. I didn't think it was the door mod, or that they were related, but I couldn't figure anything out so I started testing and I can verify, when I fully depress the flipper button, the upper left flipper isn't quite in sync when I have the color changing door mod on. When I turn off the mod, it seems that the flipper is back in sync and a fully depressed button fires in sync with the bottom left flipper. It's pretty obvious and instantaneously affected by the mod. On = a hair out of sync and sometimes weak and not a full fire. Off = normal left side flipper activity.

So the mod gets +12volt from the pcb just underneath the left flipper (which also powers the coin door lamps and switches). Does that board have anything to do with the flipper system in a TZ?

Could there possibly be a correlation between the door mod and the flipper system? Why would having the mod on affect the left flipper system but not the right? Any thoughts or am I crazy?

Thanks for your response. The LED strips are installed behind the translite but in front of the white wood that holds the translit lamps. Not sure how the LED light would be hitting anything on the flipper opto's. I've even tested with the translite removed and the white door swung all the way open and the problem remains.

Bump for any other ideas?

If I unplug the door mod, the problem goes away completely. As soon as I plug it back in, the flippers are out of sync on the left hand side. The upper flipper fires a little late and it sounds like a quick 1-2 click when the flippers fully extend instead of fully in sync extension.

Haha thanks. It is really noticeable. I may take some video of it tonight.

Can anybody tell me how exactly to test 12v with my DMM and where on the boards? I'm wondering if the 12v dips when I have the door mod on. I'd like to test all the spots along the chain to see if I'm getting a good 12 volts. But I'm pretty new at this. I can follow directions like a champ. I'd like to test the power driver board, the opto board (what is the board at the top left of the backbox?). Then eventually I'd like to test the coils (all with mod on and mod off).

PROGRESS!!! I had all 4 flippers completely rebuilt.. new coils, stops, arms, eos switches, springs... the works (this was good anyways because one coil had a diode missing and all 4 coils were completely heat stressed where I could not get the coil sleeve out).

But, the problem remained. If I turned on the door mod, the left side flippers became out of sync and weaker instantly the upper left would be weaker.

So I swapped the flipper opto boards from left to right and guess what, now the right side has the problem and the left side is fine!!! Problem found. So here is my question. Should I order new opto boards and if so which of the following?
http://mad-amusements.com/product.php?id_product=794
or
http://www.marcospecialties.com/pinball-parts/A-17316-GLM
or
??????

The original part is: A-15878
Can I manually repair the circuit board and if so, where should I be checking? I've cleaned the black opto and interrupter but still no dice.

Does anybody have one or two of the originals they'd be willing to sell me or am I better off with an option above? Thanks again for all the help!

Hmm... have you tried the mad-amusement ones or are they the same. What about these:
ebay.com link: Bally Williams WMS Pinball PCB Board A 15878 Flipper x2

So I guess trying to manually repair the board isn't worth the trouble... Just wonder if it's a simple diode or something.

Is this what you're referring to? http://ksarcade.net/optos-1/type-1-flipper-opto-board-a-15878.html It appears to be a rebuilt one but I assume it functions exactly the same as the original part? Is the actuator hard to transfer?

Okay I ordered two because I want them to be the same and feel the same. I'll look to get my existing one repaired and then have a spare set.

While I wait for shipping, I've heard you can solder together pins 1 & 2 on the old flipper opto (just but a solder link between the two on the back of the board on the connector) and that will make both flippers work together with the same trigger. Is that true and something to consider doing?

hmm weird. Talking with Ray @ Action Pinball and it sounds like he does it all the time. I guess since I have new ones coming it wouldn't hurt to try. Anybody else have input?

Just to put some closure on this thread, it definitely ended up being my Type 1 flipper opto. Even after swapping the opto elements on the "bad board". A new Type 1 flipper from K's Arcade completely resolved the issue.