Those lights are routed to/controlled by the aux lamp board. This is the one that is on the back of the light panel when you open the backbox.

Start by inspecting the board, and all connectors to make sure everything is fully seated.

This is most likely just a flakey socket, since it sounds like it’s intermittent. We can tackle that issue later.

Yes, aux lamp board does t show any smoking guns. How does the main lamp board look ? It’s the one in bottom left of the back box.
Can you also get a pic of the mpu? Top left board in the back box. These are notorious for having a battery puke on the board and causing issues.

Looks like you've got a corrosion issue on your MPU. It's hard to say where else it has spread to, but it should be addressed.

This may or may not be the cause of the lights staying lit, but it will be difficult to determine without taking care of it first.

Capture (resized).PNG

You've got a couple options:
-Clean the board yourself (consult pinwiki for details). This involves desoldering & soldering many items
-Swap out the MPU from another game you have (EBD, Lost World) to test. You'll need to swap the ROM too, located at U2
-Buy a replacement new MPU (they're good to have on hand for trouble shooting purposes, even if you fix the original)
-Buy a used MPU (they show up in the market quite often)
-Borrow a MPU for testing

That could be saved with enough time, effort, and skill. But, when a replacement is $160, you have to figure out if it’s worth it.

Have you put the lost world mpu in? Did the lights issue change?

Sorry for slow response. After looking at the two mpu’s you’d have to swap some jumper for it to work properly.
The centaur mpu has been set to allow just one rom to be used, and the lost world is still using two.

If they were both set up for the same number of chips, you would still need to change all the dip switches to match.

That’s not too uncommon. It looks like it has been repaired. For the time, leave it, and if a coil isn’t working, we’ll address that at that time.

The mpu board you linked will work. Altek makes a good board, and lots of places sell them.

Another option, for a little cheaper is here. This is a good board and works just the same:

https://nvram.weebly.com/bally---stern-pcbs.html

No that’s like that from the factory. You can leave it.

On a side note: On the lost world mpu, is there a battery still attached (it will be at the bottom of the board). If it looks original, cut it off right now, before it kills the board, like the centaur mpu. Just take cutters and snip both ends, semi-close to the board. When you’re ready to tackle the lost world, you can replace the battery then.

Well, that's not necessarily unexpected. But know we know that the MPU is good. What we don't know is if the connectors are good. Or the aux lamp driver.

So the aux lamp driver board controls these lights, and some others:

Capture (resized).PNG

Both of the slingshots, both pop bumpers, and the chamber feature (top left corner of the pf) lights are controlled by the aux board.

Once the game fully boots up, what do the chamber lights do? And sling lights? And pop bumper lights? What do they do once you start a game?

Most likely, if you’re not into board repair. But it still may not fix it. It could still be corroded connectors.

So if you buy a new aux lamp board, and it still occurs, you’ll have to re-pin the connectors. Not a tough job, just need a crimped (you’re welcome to borrow my spare)

But yes, next step would be new aux lamp board. (Sorry, pinball isn’t very cheap if you can’t repair everything)

Awesome. Good job!

Yea those are the ones. Just reheating the current solder and adding a little. Technically the proper way is to remove the old, and replace. But reheating and adding will be sufficient for now.

Just online. I can float you a couple if needed, but they’re good to have available.

When the game is on, if you wiggle the connectors (on aux lamp board, and mpu) does the lights change? Of course, please be careful.

So, it's looking like the aux lamp board has a address issue. It's either coming one of the chips has failed, or it's not getting the data correctly. The first would be remedied by a new aux lamp board. The second would be by re-pinning the connectors, and reflowing the headers.

Woohoo. Good job.

Keep them. You can learn to repair them now. Next time you won’t need to go out and buy a new one.