(Topic ID: 534)

Twilight Zone possible short?

By mjruser

11 years ago

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  • 8 posts
  • 2 Pinsiders participating
  • Latest reply 11 years ago by mjruser
  • Topic is favorited by 1 Pinsider


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#1 11 years ago

Hello All,

First of all thank you in advance for any posts! Just recently got our twilight zone out of storage after 8 years. Replaced the original power board with the new aftermarket one and the game was working perfectly, then during game play the machine stopped working and a hard power cycle didn't reset it. On power up there is a distinct hum from the speakers and after about 15 seconds the machine 'jitters' the lights, flippers and such will momentarily activate all at once, randomly and a few dots are displayed randomly on the display. I'm unable to get any debug info from the cpu led's as it doesn't go though the startup cycle.

Any ideas on what it might be or how to start 'debugging' it. Thanks again!

Kind Regards,
Mike Randolph
Grants Pass, Oregon.

#2 11 years ago

First start with this guide:


I'm sure more people will help soon as several own that specific machine and will most likely have good suggestions. Oh btw ... did you check/replace the big filter capacitor on the power supply ??? It might be drying out and going bad after all these years.

#3 11 years ago

The capacitor will look something like this:


#4 11 years ago


Thanks for the post, I've spent hours reading that excellent repair guide and debugging earlier issues. However I'm unable to even get to the point where I can 'debug' with the guide.

Just replaced the entire power supply board, so unless the cap is located somewhere else I'm not looking, it's new with the power supply board or did you mean it's on/next to the actual power supply in the bottom of the machine?

Thank you

#5 11 years ago

It usually mounted separate somewhere in the backglass cabinet. It's quite large. I guess I should have put a coin next to that in the picture. That particular capacitor is about 3.5 inches in diameter. It's not part of the power supply board but a main power supply component that often goes bad in an aging machine. The electrolyte solution inside dries up over time.

I don't know that particular machine so it might not use one being newer. Those connections on top are screws.

#6 11 years ago


Thanks again for the post, I appreciate it!

Looked around and didn't see anything like that in the TZ, so perhaps it doesn't have one or it's different?


#7 11 years ago

Try reseating all your eproms ... it's possible there are just some dirty connections in the chip sockets after all that time. Trying to help.

#8 11 years ago

Hello Brokedad,

Thank you so much for the help. EPROM for the win! Really like TZ, but it feels a bit like a foreign sports car...5 hours of maintance per 1 hour of drive time. Having it sit for 8 years, wasn't a real good thing I'm guessing.


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