(Topic ID: 22753)

JP T-rex not moving left/right — SOLVED

By accidental

11 years ago


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#1 11 years ago

Since I got my JP the T-rex hasn't been moving left to right. The guy I bought the pin off said it was working before transit so the fault has to be from transit. This seems believable because the occasions I have enabled the left/right action in the operator settings he has moved intermittently.

This leads me to believe that it is a dodgy connection somewhere. Sometimes, even with t-rex left/right disabled, during gameplay he'd randomly chomp his jaw once in a dozen games or so. I'm guessing that this chomping would normally be accompanied by left/right movement if it were turned on, so whenever he chomps during gameplay is when the dodgy connection happens to be working.

So today I decided to dedicate some time to try to fix the issue. When I turn left/right on in the settings he won't move in diagnostic mode at all. In both diagnostic mode and normal boot-test mode I can hear the relay switching attempting to move him. There was one occasion when he did start moving reliably and I was pleased but after moving around some of the wiring harness to do some more work he stopped working again. I am unsure if the connection issue is under the play field or somewhere along the wiring snake to the back box.

I have checked under the relay board and the shaker motor board for cracked solder and they appear to be perfect. The relay is switching as it should. When I test with a volt meter there is 35 volts passing through when switched one direction. When switched in the other direction there are no volts passing through. I believe the shaker motor uses the same relay and this is operating as it should.

Can anyone suggest where/what/how to test to diagnose the fault and find the dodgy connection? Thanks!

#2 11 years ago

Bump

Even though the relay solder points all look good to my eye, would it be worth reflowing them anyway? And should I try cleaning inside the relay as well?

#3 11 years ago

Have you gone into test mode for the T-Rex to see if you can make him turn there? When you say intermittent, do you mean that some days/games he will turn back and forth normally. Or that when he does turn he will do so in a kind of start and stop fashion?

If it is the start and stop one, then it sounds to me like there is no connection issue. Sporadic movement is the normal symptom of a bad gearbox. Google the T-rex motors and you will get plenty of information on how many problems there are with them. Essentially your gears are likely shot. Most people with this problem just turn of the left right movement because as long as the T-rex eats the ball, they are happy. The motor can be pricey.

If you do replace the motor, make sure you update your roms, as the newer code puts less wear on the gears.

#4 11 years ago
Quoted from daley:

If you do replace the motor, make sure you update your roms, as the newer code puts less wear on the gears.

How? Move T-Rex less during gameplay?

#5 11 years ago

If he is moving but choppy movements it is the motor. Had that same problem the wire going to the motor was broken rt ar the wire coil.

#6 11 years ago
Quoted from daley:

Have you gone into test mode for the T-Rex to see if you can make him turn there? When you say intermittent, do you mean that some days/games he will turn back and forth normally. Or that when he does turn he will do so in a kind of start and stop fashion?

Yes I have always been testing in diagnostic mode because I have been leaving t-rex left/right turned off to have normal gameplay. If I leave it on then sometimes during gameplay he'll move off the center switch and be stuck there and won't pick up the ball, so I have just been centering him and turning left/right off so he'll stay there and eat the ball.

Yesterday when having time to diagnose the fault I turned left/right movement on and noticed that he was moving just fine. But after fixing a flipper issue later that day he stopped working. I'm not sure if the shaker motor action or even just the movement of the wiring harness when raising/lowering the PF is enough to break the connection, but whatever it is I can't seem to find it but I'm having trouble knowing where I should look. That's where I need your help

Quoted from dannunz:

If he is moving but choppy movements it is the motor. Had that same problem the wire going to the motor was broken rt ar the wire coil.

Where was this broken connection of yours? At the wire coil? What is that?

#7 11 years ago
Quoted from Crash:

How? Move T-Rex less during gameplay?

Nope. It is uses rapid pulses to the motor instead of full power on and off. It is supposed to cause less wear on the gears.

Lots of topics on it out there.

2 months later
#8 11 years ago

Just to round out this thread for anyone who is looking for a solution in the future …

The fix for me ended up being a reflow of all the solder joints in board above the shaker motor. I couldn't visually identify which was the culprit so I reflowed them all.

The board looks like this one:

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#9 11 years ago

is the left right motion turned off in the menus???

#10 11 years ago
Quoted from scottc:

is the left right motion turned off in the menus???

And if it's not, it probably should be.

The left and right thing is kinda clunky and not exactly impressive. (In fact, I think the game moves along a lot better without the T-Rex taking the time to find his center before grabbing the ball.)

The star of the whole show is that ball-chomping action, and if it does that, then bravo.

#11 11 years ago
Quoted from scottc:

is the left right motion turned off in the menus???

Sorry, I solved this ages ago — I should probably update the thread title!

I just realised that I forgot to add the solution to the thread so I did this in order to be hopefully helpful to future JP owners trying to solve this problem.

Quoted from Fatsquatch:

The left and right thing is kinda clunky and not exactly impressive. (In fact, I think the game moves along a lot better without the T-Rex taking the time to find his center before grabbing the ball.)

Maybe it's novelty factor for me not having it work for the longest time, but I think it's great when the T-Rex moves! He moves smoothly for me, maybe if he is clunky then the gearbox needs servicing.

I actually found that with left/right turned on the animations were smoother. For example, with it turned off he'd be still for while before bending to pick up the ball. With left/right turned on he bends over immediately after hitting the center switch.

#12 11 years ago

What was the solution?

#13 11 years ago

It was in the post you replied to above

Quoted from accidental:

The fix for me ended up being a reflow of all the solder joints in board above the shaker motor. I couldn't visually identify which was the culprit so I reflowed them all.

9 months later
#14 10 years ago

having a few issues with my T Rex, moving sideways very slowing or nothing, removed motor & bench tested it @ 6v seems ok, motor mounted in gearbox about 4.5v, thinking the gearbox is messed up, sometimes the gearbox jams up,

thinking new gear box & motor & new roms just to be sure?

#15 10 years ago

I worked on a JP that had this problem. The l/r movement was so sluggish, that the trex could not find his center before the CPU would disable the l/r movement.

To correct the problem, I added full-wave rectification for the l/r motor, which greatly improved the trex l/r movement. If you look at the circuit board above, you'll see 3 diodes. 2 are for full wave rectification of the shaker motor, and 1 is for half wave rectification of the trex l/r motor. Since the AC feed for this comes from a center-tapped part of the transformer (see manual pg. 46), you can easily add one diode and one fuse to the circuit board above and feed a full wave rectified signal to the l/r motor (see page 49, left side). If you want to change it back to half wave rectified (original) later, you simply remove one of two the fuses for the l/r motor.

fullwave.giffullwave.gif

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4 months later
#16 10 years ago

Are you saying T-Rex moves very slow with CPU ROM 5.01 due to the fact that PWM is performed on the motor AND power going to the motor is only partially rectified?

6 years later
#17 3 years ago
Quoted from Crash:

Are you saying T-Rex moves very slow with CPU ROM 5.01 due to the fact that PWM is performed on the motor AND power going to the motor is only partially rectified?

yes, same happened to me, did the modification for full wave rectification and now its ok, pwm to slow down the motor does not seem to me a good idea for the gearbox as the motor is allways in stop and go process

1 year later
#18 2 years ago
Quoted from KenH:

I worked on a JP that had this problem. The l/r movement was so sluggish, that the trex could not find his center before the CPU would disable the l/r movement.
To correct the problem, I added full-wave rectification for the l/r motor, which greatly improved the trex l/r movement. If you look at the circuit board above, you'll see 3 diodes. 2 are for full wave rectification of the shaker motor, and 1 is for half wave rectification of the trex l/r motor. Since the AC feed for this comes from a center-tapped part of the transformer (see manual pg. 46), you can easily add one diode and one fuse to the circuit board above and feed a full wave rectified signal to the l/r motor (see page 49, left side). If you want to change it back to half wave rectified (original) later, you simply remove one of two the fuses for the l/r motor.

I’m looking to add full wave rectification for the left right motor and I want to double check so I don’t mess anything up.
Am I running a wire with fuse and diode from the gry-grn wire on J1 to the gry-blu wire on J3?

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#19 2 years ago

Jumper from gry-grn wire to new fuse in series with non-banded end of new diode...then banded end of new diode connected to banded end of diode that is not already connected to another diode (D1 it looks like).

#20 2 years ago

The D1 diode is the only trace going to J3 so I tied into the gry-blu wire.
It works great!!
T-Rex is much smoother, eats the ball every time, and twice as fast going left/right!

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1 year later
#21 11 months ago

So does it matter what size diode to use? Will anything work? Or should I match the diode to be the same as the ones on the board we are bypassing

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