(Topic ID: 80046)

Dr. Who Machine Mini Playfield Not locking both balls. Opto targets Not Working

By StotzBotz

7 years ago

Topic Stats

  • 8 posts
  • 3 Pinsiders participating
  • Latest reply 7 years ago by pinball_faz
  • No one calls this topic a favorite


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#1 7 years ago

Sorry to be a pest about this problem but I'm stumped and in need of enjoying my Dr. Who machine. This feature worked fine a few days ago but now I can't get both balls to lock in place on the mini playfield Time Expander. It will lock 1 ball then when you try to lock the other it makes the usual sound but spits it back out. The 5 opto target switches in the second level don't seem to be registering and when in test mode switch 71 thru 75 are indicated as OFF. Is there a way I can turn these ON in settings menu or does this mean the opto board is damaged? I've pushed them in in the test mode with no change so they aren't registering. I've re connected the 12 pin plugs coming from the min playfield and am getting an angled screwdriver today to remove the opto target assembly to see if there is a wire loose. Just wondered if there is anything else that I can try. I'm not sure if the 2 problems are related or if there is a place on the main board I should be looking at. I so much appreciate anyone's help as I have had this game barely a week and knowing how fun it is to play when working properly it's really frustrating. Many thanks in advance.

#2 7 years ago

As said on RGP and in other posts, you need to check what's causing the opto switch problem.

Just as a test, I pulled the connector for the optos. I get your exact condition.

This issue could be as simple as the connector is unplugged; a broken wire; or perhaps the optos themselves are failing.

Optos always send the signal. If the signal is not being received (or the receiver has failed), the signal from the switch is gone.


#3 7 years ago

Yes I pulled out the 5 target opto assembly and for some reason there are 2 opto receivers missing for the 74 and 75 switch. Also there is some of the paper covering damaged on the side of the assembly which might be letting light in. Ordering a set of opto boards from Marco hoping that will solve my problems. Sorry for the annoyance.

#4 7 years ago

My DW was in similar condition when I purchased it. The mini playfield was not working in game because the optos for the five targets weren't working. I had a few burnt out emitters and a couple broken off receivers. I replaced the optos and all was well. Good luck.

#5 7 years ago

Thank you. This machine is so fun when working properly. I just can't understand how it worked the first few days I got it then all went wacky on it. Those receivers missing should have not allowed it to work properly. Oh well. Hoping for the best when Marco takes care of me.

#6 7 years ago

Williams compensates for switches that are out. I'm not sure how it would compensate for all buttons being out, but if one or two is out, it will allow the game to progress with only three of the switches working.

There's a key sequence to reset switch errors. If you press the credit button during Test 13, Test 14, Test 15 it resets all errors. I would guess if you did this, it would remove the instructions to compensate as well. It takes 30 games or 90 balls for the game to start compensating again.

Is that possible that you reset the errors??


#7 7 years ago

Possibly I did or the fact that the machine sat up for several months without batteries or power might have done it. I did get the opto boards for the 5 target assembly in from Marco, installed and wrapped with electrical tape and installed back in the machine. Happily I am exterminating Deleks once more and all is fine with the mini playfield. What a unique machine this is. Thanks again for all the help.

#8 7 years ago

Excellent! Congrats!

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