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(Topic ID: 264643)

Jurassic Park (DE) T-Rex Left/Right Issue


By grantopia

7 months ago



Topic Stats

  • 8 posts
  • 5 Pinsiders participating
  • Latest reply 7 months ago by grantopia
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#1 7 months ago

The left/right movement on my t-rex hasn't worked since I acquired this game awhile ago. The up/down and ball eating work fine so I've just never been that motivated to look into it. Since we're pretty house bound I figured why not see if I can crack it.

All the wiring looks good on the motors. When I go into the t-rex test, when I use the left and right flipper buttons I can hear a relay click and the motor sounds like its running, but there is no movement left and right.

In the research I've done it seems like alot of people have had this problem and the fix is always a little different. The schematics in the manual aren't that great (or I'm dumb which is just as likely) but it looks like Q27 controls the left right movement. I'm wondering if that is just bad since it it sounds like the relay and motor are working in test.

In looking at the switche, the one on the right of the underside of the playfield has this diode wired on....is that correct?

If anyone has any ideas please let me know. Just wanted to see if there was something else I should check out before I pull the mpu and Q27.

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#2 7 months ago

Yep mine looks the same. I’m shopping the game right now, so if there’s anything else you need pics of just ask.

B20B077D-3269-410E-B43B-E8B09DF5D570 (resized).jpeg
#3 7 months ago

If a small relay on a printed circuit boards runs the motor for this. I'd pull the board and reflow the solder on it first. Age and vibration is hard on those DE motor boards.

LTG : )

#4 7 months ago
Quoted from LTG:

If a small relay on a printed circuit boards runs the motor for this. I'd pull the board and reflow the solder on it first. Age and vibration is hard on those DE motor boards.
LTG : )

I'll see if I can track down where the relay for it is. These schematics are not the best ha.

#5 7 months ago
Quoted from grantopia:

it looks like Q27 controls the left right movement. I'm wondering if that is just bad since it it sounds like the relay and motor are working in test.

That is what I found causing the issue on a friend's JP. Go for it.

#6 7 months ago
Quoted from grantopia:

I'll see if I can track down where the relay for it is. These schematics are not the best ha.

Under the playfield, further from Rex than you would expect. Reflow worked for me when Rex would only go one direction.

https://pinside.com/pinball/forum/topic/jurassic-park-club/page/91#post-4571777

#7 7 months ago

The relay had all the wires soldered to the pins, so I repinned the connector and the header pins and reflowed all the solder hoping I'd get lucky. No change after that so I'll probably pull the board and test the transistor.

#8 7 months ago

Q27 and Q24 both tested good as did the pre driver for Q27. I swapped Q27 anyway since I had the board out and no change there. Is there a good way to figure out if the problem is upstream in the board or down at the mech itself?

If I've got the schematic right it looks like the PPB board is not used in the movement at all. Q27, Q19 and R70 all test good. After that on the board it looks looks there are 2 ICs, a 7408 and then a 6821. Is there a way to check at the motor to rule out a bad motor before I go further back into the board?

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