DE Jurassic Park T-Rex repair question

wontwa

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Anyone know of any good tutorials online for troubleshooting the T-Rex in this game? Mine generally seems to work fine - moves back and forth, neck moves forward and back, etc. However, when it leans down to eat the ball it goes all the way down but does not open it's mouth to grab it, then goes back up, chomps a couple of times, then the ball gets kicked back into play. Not really sure where to start with this. I did look in the main menu and the settings are turned on for it to eat the ball. THe diagnostic that starts when the game is turned on doesn't indicate anything is wrong.
 
That's a weird issue. Do you have the latest ROM version? I had an older one and when it did the test cycle at the beginning it would do the chomp as if eating a ball, but the newer ROM doesn't do that. You might want to go to the newest version anyways because it's supposed to cut down on the wear and tear of the T-Rex motors.

I also found this service bulletin which details the operation of the T-Rex and some troubleshooting tips, http://www.sternpinball.com/downloads/sb39a.pdf .
 
The message that comes up at the beginning says, A4.00 6/7/93 - so I'm guessing that's not the latest ROM version. Thanks for the tips (and the link). I've only had the game two days and it's my first DMD pin, so still pretty new to it. Can the ROMs be easily ordered somewhere, or am I looking at downloading them and getting a chip burner? (sorry for the newb question).
 
The latest ROM version is 5.10 so you should definitely upgrade. You can buy the roms from most pinball suppliers, marcospecialties, pinballlife, actionpinball, and probably others. If you have access to a chip burner and the chips, then you can certainly burn them yourself.

The nice thing about Jurassic Park is that it's very popular so you should be able to find a lot of resources on fixing/troubleshooting it.
 
I have the 5.x series ROMs, which are the latest version, and the T-Rex chomps during diagnostics. Check the coil and linkage for binding when the T-Rex drops. The mouth should be open all the time, when the head lowers the mouth opens slightly more, then the coil fires when it is down to close the mouth completely. You can easily remove the cover from the T-rex and check it, it is held by one screw at the back. Use the diagnostics in the menu to raise and lower the head and see how it behaves.

Check the wires to the coil, if it has a break and looses its connection when the down, the coil won't fire and close the mouth. This could explain why it chomps when up but the mouth won't close when down.
 
I have the 5.x series ROMs, which are the latest version, and the T-Rex chomps during diagnostics. Check the coil and linkage for binding when the T-Rex drops. The mouth should be open all the time, when the head lowers the mouth opens slightly more, then the coil fires when it is down to close the mouth completely. You can easily remove the cover from the T-rex and check it, it is held by one screw at the back. Use the diagnostics in the menu to raise and lower the head and see how it behaves.

Check the wires to the coil, if it has a break and looses its connection when the down, the coil won't fire and close the mouth. This could explain why it chomps when up but the mouth won't close when down.

Everything sounds right except the part where the coil should fire to close the mouth completely. Checking that out seems like a great starting point. Thanks for the tips!
 
Dang Wontwa, I am in Grand Rapids and have looking for a Jurassic for over a year! May I ask where you found this gem??

Thanks and enjoy!
 
I had the same issue with mine. It turned out to be the metal piece that attaches the motor to the mouth. I guess they made them out of some weak metal that is prone to breaking at the thin point. A replacement steel version cost me like $20 and fixed the issue right up. Takes a little work to get into his mouth though, tiny space to work, lots of fishing with needle nose pliers. Good luck.
 
I had the same issue with mine. It turned out to be the metal piece that attaches the motor to the mouth. I guess they made them out of some weak metal that is prone to breaking at the thin point. A replacement steel version cost me like $20 and fixed the issue right up. Takes a little work to get into his mouth though, tiny space to work, lots of fishing with needle nose pliers. Good luck.

Did yours do the chomping while in the upright position even when the metal was broken?

Was there somewhere in particular that you ordered the replacement steel, or did you have it fabricated?

Thanks for the suggestions!
 
Dang Wontwa, I am in Grand Rapids and have looking for a Jurassic for over a year! May I ask where you found this gem??

Thanks and enjoy!

One showed up on Jackson's CL a month or so ago. Was able to get a solid deal on it, and the timing worked out perfect. The drive on black ice roads in a cargo van, however - not so great.

Good luck finding one, I'm really happy with it!
 
Did yours do the chomping while in the upright position even when the metal was broken?

Was there somewhere in particular that you ordered the replacement steel, or did you have it fabricated?

Thanks for the suggestions!

I don't think it chomped when it was powering up, it really couldn't have since that metal piece was hanging off of it inside. I got it at Marco Specialties online. Looks like it cost me more than $20, oops. It worked like a charm once I determined that was the problem. There is a motor that runs the mouth (like my wife's, hey-o) so you should be able to see if that's working when you boot up. It will snap a few times right after it moves back and forth.
Here's a link to the piece...
http://www.marcospecialties.com/product.asp?ic=535-6640-00
 
I appreciate the advice, but I'm thinking that I don't have the same issue you had. Mine chomps up and down when in the upright position, it just doesn't chomp to grab the ball when down. I took a quick look and noticed that the grey sheathing that holds all of the wires going to the dinosaurs head is sliced open in a spot (where the head would go into the upright position) - so I'm guessing it's likely what the earlier posts suggested, that a wire is likely cut/not making a connection. Hope to get a closer look at it later... Thanks, though!
 
Is the T-Rex triggering the down switch when it is fully down? Go into the test mode to see.

Cant say for sure but maybe the game only triggers the mouth closed right after the down switch is triggered.
 
Just thought I'd update this thread should anyone do a search in the future with a similar issue. Ended up being that the sheathing for the two wires that go to the t-rex was sliced, and on closer examination - the white wire was completely sheared in half. They were connecting just enough while in the upright position to move the jaws, but when the t-rex moved his head all the way down there was no connection. A little soldering and everything works great now!
 
Mine had the same thing. When I fixed mine I also took out a screw at the base of T-Rex that had a plastic tab that held the wires in a certain place. Didn't seem like it was going to mess anything up and the wires could move more freely now when the T-Rex moved. Basically the wires were not bending in the exact same spot every time. Something to try if they break again.

Congrats getting it fixed. Nothing worse than a sick dino.
 
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