(Topic ID: 240840)

JP trex issues


By Jimmyapple

1 year ago



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  • 39 posts
  • 9 Pinsiders participating
  • Latest reply 1 year ago by Jimmyapple
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#1 1 year ago

Hi all. Keep having switch issues with my JP and the trex apparently. All the switches test fine. During the diagnostic and game phases, however, the trex doesn’t always chomp (eat the ball) and sometimes the up and down sensors do not register. Again they do during test phase but not gameplay. He intermittently eats the ball but most times not. I tried adjusting the switches but no fix yet. Thoughts?

Jimmy

#2 1 year ago

check if yours is one of the early games prior to 87012. There is a service bulletin for this game specifically for the t-rex. There is a article on it in playmeter magazine.

Also check if you have the latest code [rom revision 5 i believe]. it helps with the dino operation. Could be binding and not operating right in game and work in test. Switches can be flaky.

Sometimes when operated slowly after not working for a game or 2 they become sticky internally and do not actuate correctly until the second time.

#3 1 year ago

I found my T-Rex had trouble eating the ball when the game was not level.

#4 1 year ago

Make sure the scoop the ball sits in isn't cracked or broken. Mine was cracked and she would drop the ball, got a new one and has worked ever since.

#5 1 year ago

If he does a LATE Chomp only on the way up I had the same problem.

Take him apart and look at the wiring. Most likely after all that up and down the wire has broken in half and is only touching when in the upright position.
I cut each side and soldered a new in between wire with more slack.

works perfect now.

#6 1 year ago

Yup agreed. Check wires, and if you want you can upgrade them to a more multistranded wire. Great for things like this but not cheap.

Oh yea.The JP article was in the vol 19 august 1993 PlayMeter mag. Check it out jurassic owners. neat read. Has great picture with Gary Stern in the egg room wth the cast of JP in the main article besides the dino update.

#7 1 year ago

Thank you all. Got some diagnostics to do and will report back. Seems like I should take the whole thing apart for now. This should be fun.

#8 1 year ago
Quoted from Jimmyapple:

Thank you all. Got some diagnostics to do and will report back. Seems like I should take the whole thing apart for now. This should be fun.

Its not that hard. Turn the machine on and then off wjen the trex lowers. Then remove the plastic playfield collar , thwn the back of Trex ( just one screw ).
Then trace the wire and consider splitting the casing to check the black and white wires at the bend point.
My white wire was broken and when i fixed it now works great. Good luck

#9 1 year ago
Quoted from Hawk007:

Yup agreed. Check wires, and if you want you can upgrade them to a more multistranded wire. Great for things like this but not cheap.
Oh yea.The JP article was in the vol 19 august 1993 PlayMeter mag. Check it out jurassic owners. neat read. Has great picture with Gary Stern in the egg room wth the cast of JP in the main article besides the dino update.

Is there a link to the article? Thanks

#10 1 year ago

Took the t Rex apart and all wires look fine and test fine. One was slightly crimped but every time I test the jaw in diagnostics it works at all levels. I tested the switches all work. Scratching my head. I’ll post pics if it will help but open to other suggestions. Again the only issue is that the trex doesn’t always pick up the ball when it goes down to do so in game play.

#11 1 year ago
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#12 1 year ago

Looks like the yellow saucer is cracked. Replace that and try to play it again. The dino will not act right if that saucer is damaged.

I will scan the pages from the magazine when I get a chance. I am looking right at the Magazine right now.

#13 1 year ago

also make sure any screws are in and tight the way they should be.

#14 1 year ago
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#15 1 year ago

There is one crimped wire slightly but still diagnostics fine. I’ll try to get a new saucer. Not sure if the wire is worth stripping. Don’t have a lot of room left

#16 1 year ago

And this is probably a dumb question but why would the plastic saucer matter if it’s cracked? If the switch works and the ejector works what would be the issue? Why would the mouth not close on it?

#17 1 year ago

the ball will not sit right or get pressed down or what have you. I cannot see how bad yours actually is but from the pic it looks cracked and may be hampering operation.
If its cracked it needs to be replaced anyways so no harm done.

#18 1 year ago

I'm having the same issue. T-rex begins to raise, then chomps. He has raised about 1/8" to 1/4" when the chomp happens so he just knocks the ball out of the hole.

#19 1 year ago

again switch adjustment is key. Plus as switches age the sweet spot changes and takes longer to activate and reset for another operation. Could be yours are just old and need replacement.

But adjusment is paramount. Once its done it works flawlessly. great design. But our favourite games are getting on in age friends.

#20 1 year ago

So odd. Mine goes down, doesn’t chomp at all, then chomps at top. The ball sits there then auto pops out. Frustrating. I’m trying to find a new saucer. It’s not cracked bad, but it is cracked. The ball registers in the saucer every time however. Just odd.

#21 1 year ago

Ya I may just order all new switches. Also while I’m in here should I oil this bad boy up or go through a cleaning? She’s dirty. I got most of the switches to be consistently on when in proper position. Sometimes up lags or is off. But again all test fine. Anyone got a link to the saucer?

#22 1 year ago

how well does your saucer switch work? Check that bad boy. If its flaky it will forget the ball is in the saucer and not chomp.

Maybe try switch test and bang on the middle of the playfield and see if any flake out. or any double switch activations or any weirdness at all and report back.

#23 1 year ago

Just clean everything and maybe the slightest wipe of grease on metal to metal contact points only. NO WD! . get synthetic grease. Great stuff. never goes bad.

#24 1 year ago

You can usually 'feel' a switch is bad when operated with your finger. It is very unlikely all your switches are bad. Not impossible...just unlikely

#25 1 year ago
Quoted from Jimmyapple:

Ya I may just order all new switches. Also while I’m in here should I oil this bad boy up or go through a cleaning? She’s dirty. I got most of the switches to be consistently on when in proper position. Sometimes up lags or is off. But again all test fine. Anyone got a link to the saucer?

Even though I don't think it's your problem:

https://www.marcospecialties.com/control/keywordsearch?SEARCH_STRING=eject+shield

#26 1 year ago

no but he needs it anyways from the look of his. I think its a switch issue for sure.

#27 1 year ago

And here's how to remove the tabs, https://pinside.com/pinball/forum/topic/jurassic-park-restoration/page/9#post-4149188. No one sells them without the tabs anymore.

#28 1 year ago

Mine didnt seem cracked very bad either (if i recall it looked a lot like yours) but it was enough to keep the ball from sitting up high enough for the rex to grab it.
It always amazes me how something being the smallest bit out of adjustment can change the way a game plays.

#29 1 year ago
Quoted from Jimmyapple:

So odd. Mine goes down, doesn’t chomp at all, then chomps at top. The ball sits there then auto pops out. Frustrating. I’m trying to find a new saucer. It’s not cracked bad, but it is cracked. The ball registers in the saucer every time however. Just odd.

Rex grabs the ball, brings it up then swallows, and chomps at the top after swallowing the ball.

#30 1 year ago
Quoted from Jimmyapple:

Ya I may just order all new switches. Also while I’m in here should I oil this bad boy up or go through a cleaning? She’s dirty. I got most of the switches to be consistently on when in proper position. Sometimes up lags or is off. But again all test fine. Anyone got a link to the saucer?

If you want to try a quick test with the saucer before buying a new one, switch the TRex saucer plastic with the one in the top right in the Boat Dock. Same part.

#31 1 year ago

So I think I figured out why it’s not working. The tRex up and down motor will sometimes go all the way around and then sometimes it goes backwards. When it goes backwards it gets caught behind the down switch and then kicks back over. If I bend the switch so it triggers both ways it doesn’t work properly. Is the motor supposed to go both ways? Or is it just supposed to go clockwise? I watched the times it ate the ball and it only ate the ball when it went clockwise.

FC578821-9427-4D2A-9969-F5CF61F83BEA (resized).jpeg
#32 1 year ago

Anyone mind showing me a picture of their switches underneath the playfield? For the tRex?

#33 1 year ago
Quoted from Jimmyapple:

So I think I figured out why it’s not working. The tRex up and down motor will sometimes go all the way around and then sometimes it goes backwards. When it goes backwards it gets caught behind the down switch and then kicks back over. If I bend the switch so it triggers both ways it doesn’t work properly. Is the motor supposed to go both ways? Or is it just supposed to go clockwise? I watched the times it ate the ball and it only ate the ball when it went clockwise.
[quoted image]

Found this in the manual, so it looks like it does turn in both directions.

trex motor (resized).JPG
#34 1 year ago

Thanks. My top switch will work going both ways but the bottom only one way. Is that normal? See how the motor hits the bottom and then goes the other way but the top doesn’t do that. I bent the switch to work both ways on the bottom but then the trex really wouldn’t work.

#35 1 year ago

Found the problem on ours. It was the classic broken wire in the harness. I figured it out by using the t-rex test mode. The jaw would snap perfectly in every position except all the way down. As soon as t-rex moved up just a fraction of an inch the jaw would start working again. I just spliced in a 1 inch piece of stranded wire, soldered it and wrapped it up in electrical tape. Works perfect now!

#36 1 year ago
Quoted from LOTR_breath:

Found the problem on ours. It was the classic broken wire in the harness. I figured it out by using the t-rex test mode. The jaw would snap perfectly in every position except all the way down. As soon as t-rex moved up just a fraction of an inch the jaw would start working again. I just spliced in a 1 inch piece of stranded wire, soldered it and wrapped it up in electrical tape. Works perfect now!

Yep. Classic issue. I had to run a new wire that bypassed the tubing that the wires run in.

#37 1 year ago
Quoted from LOTR_breath:

Found this in the manual, so it looks like it does turn in both directions.
[quoted image]

That's a diagram of the left/right motor and bi-directional relay for it.

The only motor that is bi-directional is the left/right motor. The up/down motor should only be turning one direction. The movement in that one direction makes the t-rex go down and up.

#38 1 year ago
Quoted from winteriscoming:

That's a diagram of the left/right motor and bi-directional relay for it.
The only motor that is bi-directional is the left/right motor. The up/down motor should only be turning one direction. The movement in that one direction makes the t-rex go down and up.

Oh, good catch. That does make more sense!

1 week later
#39 1 year ago

Mine only swallows the ball half time now. The Rex registers but the down switch is causing the trex to stay down and multiple chomp the ball, then go back up without swallowing. Then the ball pops out. It doesn’t impact play, other than being annoying. It’s hard to describe but it’s the bidirectional counterclockwise motion that causes it and “fixes” itself half the time (turns clockwise) and he works perfectly. So confused, so if anyone has any ideas I’m all ears. In test mode all switches test fine. Otherwise I’ll just flip away thanks again!

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