Hi everyone! This is my first post here. I just bought a Taxi, brought it home and moved it into my apartment. I got it set up and it booted no problem and I played 2 games with no issues. On my third game I earned a replay at one million points, the knocker coil fired, and the game froze as if I had tilted. No flippers, displays went out, it just kept playing the main theme with with the GI lights on. I turned the game off and on and now it will not boot, it just makes various high pitched noises. The 5v light comes on on the MPU but the other two do not. I took a look around for any obvious blown fuses or loose connections from moving the game but didn't find anything. I'm still very new to pinball so any help would be greatly appreciated, I'm well versed in arcade repair so I'm very comfortable with a meter and soldering iron, I just need a push in the right direction!

Thank you so much for that link! After reading through most of the 11B info I'm thinking this is a power problem, I'm not getting anything from the diagnostic or reset lights on power up or when the CPU test switch is pressed and I'm not getting anything on the displays. All I get is various weird high pitched noises and the 5v led comes on. The game was playing perfectly until the knocker coil fired. Of course I left my meter at the workshop today, I'm going to pick that up now and will report back with voltage readings!

Got my meter and checked voltages on the power supply, I have 4.9v at test point 1 and nothing on the 12v and - 12v test points. 5v at the MPU test points reads 4.83 which seems low to me. I reseated all the connectors and no change. What should I be checking next?

Absolutely, here is a picture of the power supply. I'm confused by the lack of both +12v and -12v. After looking at the schematics for the power supply it looks like I should at least have -12v even if there is something wrong with the bridge rectifier. F4 and F5 both tested good, and there is 4.9v on the 5v test point and on the 5v pins of J1. No +12 or -12v on the respective pins of J1, so that's why the MPU won't boot. But where the 12v went I've got no idea.

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I pulled my power supply out and tested it in my friend's Black Knight 2000 and it worked no problem. I put it back in mine and got nothing. I reseated some connectors and poked around a bit and then got the game to boot with "adjustment error" on the display and all settings back to factory. My research is saying that's usually a battery problem. The seller told me the battery was replaced recently, should I look into replacing it again?

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Here are a few better pictures of the battery area. It definitely looks like there was corrosion that was cleaned around the chips, and some damage and a solder bridge above U31. I poked around a little with the meter and everything seems to have continuity like it should. Should I look into getting this board cleaned and repaired again? Thank you all so much for your help so far! The game has been playing fine the last 2 days, I earned a jackpot and a replay today and the game didn't lock like before, I'm not sure what happened originally but hopefully just a one time issue from moving the game.

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I've been playing a lot today with no issues, but at the end of my last game I got a match and the game locked up when the knocker fired. The displays went out and it just sat with frozen playfield lights. Fortunately this time it booted no problem after being power cycled. Why would the knocker sometimes crash the game?

Edit: it locked up mid game as well, looping the "increase jackpot" music. It didn't boot the first time I turned it off and on but booted the second time. This seems like a power issue, my guess is the 5v is dropping and making the MPU lock up but I'm hoping someone might have a better guess.

I ran the coil test and the knocker crashed the game again so there is definitely a problem there. The knocker itself moves freely and smoothly in the coil, and the info I found said the ae-26-1200 coil doesn't have a diode on it. Is there a diode on the driver board that could be bad?

Edit: I removed U41 and U42 to check for corrosion on the legs, and now the game is back to not booting. It just makes a high pitched or buzzing noise when turned on. I double checked all the voltages and they are good, and the reset circuit shows +5v. Should I look into cleaning the sockets for U41 and U42?

Another update: I put my MPU in a Black Knight 2000 and it's playing perfectly. It didn't boot with just the power connected but is booting every time with everything connected and the ROMs swapped over. Ran the coil test and the knocker isn't crashing the game. I did clean up some of the corrosion on my MPU before putting it in BK2K, maybe that was enough to bring it back to life? I'm not really sure where to go from here, my efforts to isolate the problem to one board aren't paying off as I had hoped. Should I be checking my driver board next? There has to be a bad diode or some other problem somewhere in line with the knocker in Taxi that is letting it crash the game. If anyone has any ideas I'd really appreciate the help!

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A little update on this problem: I've currently got Taxi's MPU and power supply running in BK2K and vice versa, and both games have been getting played daily with no issues. I've scored plenty of jackpots and replays on both and neither has ever crashed. Since they're both doing so well I'm leaving them as is for now, I'm guessing cleaning the boards and reseating all connectors chased away whatever ghost was in my Taxi to begin with. Thank you all so much for your help on this! If you ever find yourself in Aurora IL stop by Yetee Station Arcade and say hi

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