Jurassic Park: T-Rex Center Switch

[StrutterAtlanta]

Having a small T-Rex problem with my recently acquired Jurassic Park
Pinball machine. The T-Rex doesn't seem to want to eat the ball. First
question: when, exactly, SHOULD the T-Rex eat the ball? I might just be
impatient!

Upon startup, the T-Rex passes the tests (well, that is, I don't get
any errors). Accessing the T-Rex test in the Diagnostics yields the
following

top - ON
bottom - OFF

center - OFF
right - OFF
left - OFF

I can open and close the jaw as well as use 'Start' to move T-Rex up
and down. He won't move side-to-side, though. And when he goes all the
way down he looks a little off-center (center being where the ball
should be).

According to the manual:
"The T-rex Top Switch must indicate ON to allow left and right
movement."

OK. That should work for me. But it doesn't.

According to the manual:
"The T-rex Center Switch must indicate ON to allow up and down
movement."

The center switch, according to my diagnostics, is 'OFF' but I can
still move T-Rex up and down with the Start button.

I'm not very experienced with these things, either. I don't know
what/where the center switch is nor do I know how to adjust it
correctly. Can anyone enlighten me? How do I make the center switch
turn 'ON'? Should I adjust the T-Rex so the jaw centers over the ball
slot? How would I do this?

Any help is greatly appreciated!

Thanks
StrutterAtlanta

[Rondogg]

What does it do during gameplay?

It should eat the first and 4th balls and also eat the ball to start
multiball (if I am not mistaken)

[Boyd Bottorff]

Post by StrutterAtlanta
Upon startup, the T-Rex passes the tests (well, that is, I don't get
any errors).

I believe, but I'm not sure, that it doesn't give you errors; it just
shuts down the dino.

Post by StrutterAtlanta
Accessing the T-Rex test in the Diagnostics yields the
following
top - ON
bottom - OFF
center - OFF
right - OFF
left - OFF

Try lifting the playfield, then manually closing the left/right/center
switches, just to check them. But if the top switch is on, and the
T-Rex doesn't *try* to move, it's probably a motor issue, or power to
the motor. Or one of the relays that controls direction of the dino.

Either that, or the dino movment was disabled at some point. There are
two adjustment settings that control this, make sure they're enabled.

Post by StrutterAtlanta
I can open and close the jaw as well as use 'Start' to move T-Rex up
and down. He won't move side-to-side, though. And when he goes all the
way down he looks a little off-center (center being where the ball
should be).

That's why you want to check the center switch. See if it is being
activated.

[StrutterAtlanta]

"Try lifting the playfield, then manually closing the left/right/center
switches, just to check
them."

This was my next step. Can you walk me through closing these switches?
I'm new at
troubleshooting these things.

"There are two adjustment settings that control this, make sure they're
enabled."

Are these the settings set to 'OFF' in the diagnostics screen? How do I
enable them?

Thanks!
jjd

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[Boyd Bottorff]

Post by StrutterAtlanta
"Try lifting the playfield, then manually closing the left/right/center
switches, just to check
them."
This was my next step. Can you walk me through closing these switches?
I'm new at
troubleshooting these things.

Get the game into switch test first. Lift the playfield enough to see
the back of it.

At the back left (bottom left of the underside, once lifted), locate the
T-rex assembly. It'll be the big part cut out of the plywood. There
will be a crescent-shaped path that has a shaft sticking through it. At
either end of the crescent is a switch with, IIRC, a long flat piece of
metal sticking out of. That metal, when pressed, presses down a little
tab sticking out of the switch. Those are the right and left switches.
As the T-Rex moves right and left, the shaft going through the guide
path presses the switches, so the game knows the dino's reached its
limit.

The center switch is located under the under-playfield ramp. Instead of
a long piece of metal sticking out of it, it's a short piece of metal
with a roller on the end. Again, the T-Rex shaft presses this switch
when Mr. Rex is at the center position.

Well, the switches can be pressed by hand-- just gently push on the
metal actuators, so that they press the tab on the switch down. Since
you're in test mode, it should register the switch you pressed.

Post by StrutterAtlanta
"There are two adjustment settings that control this, make sure they're
enabled."
Are these the settings set to 'OFF' in the diagnostics screen? How do I
enable them?

They're not in diagnostics, they're in adjustments. Get to the
adjustments menu (same way you get to diagnostics, except that the
middle button needs to be in the other position-- press it once, first.
You should, IIRC correctly, see audits first. Go through the audits
section, until you get to adjustments. Step through the adjustments
until you see "Expand Adjusts". Press the start button so it says
"yes". Continue through adjusts until you see "Move T-Rex Up/Down (or
maybe L/R; I forget which comes first). It should say "yes" If not,
press the start button to change it. The next adjust will be the other
"Move T-Rex" adjust. Again, make sure it says "yes".

BTW, I'm doing this from memory-- a few details may be off a bit, but
hopefully this should be enough to get you going.

[StrutterAtlanta]

"What does it do during gameplay? It should eat the first and 4th balls
and also eat the ball to
start multiball (if I am not mistaken)"

During gameplay, the first time I hit the T-Rex I hear the audio of a
person screaming, as if
eaten. Then nothing happens. The T-Rex sits there. After 10-15 seconds,
the jaw moves about
five times and my ball is kicked out of the indent it sits in.

I'm assuming the T-Rex is supposed to bend down and eat the ball
here...right?

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[AsiaPinball]

Yes, the T-rex is meant to bend down and eat the ball here.

From your first post, my JP does not line up exactly to the centre (it

is slightly to the left of centre). This does not cause any problems
during gameplay - i.e. when the dino eats the ball, it centres OK -
therefore, I doubt this is your problem.

The underplayfield pcb that links to the dino causes problems. Search
the group for "JP dino pcb" and you will get a thread that discusses
this problem. Reflowing the joints on the pcb can often solve the
problem of no left / right movement.

It could also be the motor that is broken - again a common fault.

Early versions of the game roms had problems with the software leading
to premature failure of the motor. If you don't have the latest roms
you should update to them to protect the motor.

You should check www.sternpinball.com for service bulletins for JP -
lots of useful information here, including theory of operation of the
TRex, which may help you solve the problem. www.marvin3m.com also
amkes some comments on these common faults.

Good luck,

Paul

[Gerry Manis]

Hi, Strutter.

What the manual says about the center switch being ON before it allows
the TRex to move up and down is correct. Here is a very simple
solution:

Go into the TRex test. Take off the playfield glass. Grab a hold of
your TRex's head, and manually move it towards the center. You'll
notice that the center switch indicator is now on. Let go of the TRex
head. Put back on the glass. Get out of diagnostics. Start a game.

That will fix it, and your TRex should work. If it doesn't, you have a
different problem. Things to check in that case:

1) Is the TRex turned on in adjustments? There is an adjustment to
simply eliminate it from working. Make sure it is on.

2) Is the up/down motor shorted in any way? Mine has this problem,
and I have to occasionally wiggle the capacitor attached at the
connector after I have lifted the playfield. (I should probably fix
this some day...) Mike at MAD Amusements (an Ebay seller) used to have
replacements on EBay. You might check with him if you need a new one.

3) You probably also have a left/right motor problem. Rick at Bay
Area Amusements used to stock these. Not sure if he does now, or not.

4) Make sure you have the latest ROMs, as there was a software bug
that caused damage to the motors (It caused the direction to be
switched too quickly, causing damage to the gears inside the gearbox of
the left/right motor). I think I got mine from Ray at Action Pinball
several years ago.

Best of luck. I really enjoy this game, especially when it all cleaned
up, and working completely!

Gerry Manis.

[Gerry Manis]

When I said manually "move" the TRex head, I meant "rotate"! Big
difference!

Best of luck,

Gerry Manis.

[StrutterAtlanta]

This is all fantastic advice, and thanks to EVERYONE for their input!
Community on the internet
is such a powerful thing.

I started with Gerry's advice: going to Diagnostic Mode and rotating the
T-Rex until he was
more on center. The center switch went to 'ON' immediately. I tried to
move him left and right
but didn't have any luck.

I did fire up a game, though, and the T-Rex ate my ball when he was
supposed to, something
he didn't do before. That was great!

So now I have to figure out the L/R aspect of it. But, for now, at least
I get to enjoy this part.

THANKS TO ALL!
jjd


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