(Topic ID: 251765)

Doctor Who intermittent Switch 74 and/or 75, mini-opto-5 error on POST


By Supernibbler

5 months ago



Topic Stats

  • 8 posts
  • 7 Pinsiders participating
  • Latest reply 4 months ago by Catch86
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#1 5 months ago

As the post title suggests I have a problem on a Bally DW that POST's an intermittent Switch 74 and/or 75 mini-opto-5 error on the power on self test. I don't know how these errors would affect game play, but the game plays absolutely fine, so I don't know if there is really a problem or not. Anybody have any ideas 1. what the problem is? 2. How it theoretically should affect game play, and 3. the fix?

I am not opposed to replacing the opto board, but if the errors do not affect game play or proper function of the game I don't really think it's necessary.

I ask this because I would like to sell the game; so obviously I would like to alleviate the symptom to sell an error free game.

#2 5 months ago

Once you progress in multiball after locking 2 balls the optos will start to complete the matrix for you, and if you have doctor 7 selected, will complete the whole board without you earning it.

It's likely a combination of the opto boards (cracked connections are common here) and maybe a warped opto carrier.... it's plastic and distorts over time (from who knows what.... I just replaced mine).

That's the good news. The bad news is you have to remove the mini playfield assembly to replace, and that's a PITA thanks to the older style playfield tilt in that game (no slide rails). You have to take off the glass molding at the top of the game, put the playfield up, disconnect the harness, loosen some screws, and angle it out.

https://www.afpinball.com/uploads/7/4/1/4/74144281/thedoctorwhominiplayfieldv1.2.pdf

is a great guide to servicing the mini pf

#3 5 months ago
Quoted from Supernibbler:

As the post title suggests I have a problem on a Bally DW that POST's an intermittent Switch 74 and/or 75 mini-opto-5 error on the power on self test. I don't know how these errors would affect game play, but the game plays absolutely fine, so I don't know if there is really a problem or not. Anybody have any ideas 1. what the problem is? 2. How it theoretically should affect game play, and 3. the fix?
I am not opposed to replacing the opto board, but if the errors do not affect game play or proper function of the game I don't really think it's necessary.
I ask this because I would like to sell the game; so obviously I would like to alleviate the symptom to sell an error free game.

Had the same issue on my DW. I had blown optos, warped carrier, so I fixed that along with installing Ulf's new linear bracket kit and now, zero issues.

#4 5 months ago
Quoted from slochar:

It's likely a combination of the opto boards (cracked connections are common here) and maybe a warped opto carrier.... it's plastic and distorts over time (from who knows what.... I just replaced mine).

+1

faz

#5 5 months ago
Quoted from Supernibbler:

As the post title suggests I have a problem on a Bally DW that POST's an intermittent Switch 74 and/or 75 mini-opto-5 error on the power on self test. I don't know how these errors would affect game play, but the game plays absolutely fine, so I don't know if there is really a problem or not. Anybody have any ideas 1. what the problem is? 2. How it theoretically should affect game play, and 3. the fix?
I am not opposed to replacing the opto board, but if the errors do not affect game play or proper function of the game I don't really think it's necessary.
I ask this because I would like to sell the game; so obviously I would like to alleviate the symptom to sell an error free game.

Suspect damaged wire harness from wear
Check for internationally broken wire(s) in the mini playfield harness:
In switch test carefully flex the harness to check if the opto's move off and on.

#6 4 months ago
Quoted from eyeamred2u:

had blown optos, warped carrier,

What is "Ulf's new linear bracket kit"? Where can I find it? How much is it? And do I have to remove the mini-playfield?

I could not find a place that had stock on the opto board.

Thanks!

#7 4 months ago

Ive removed the opto assy without removing the entire pf. I usually cycle pf up halfway after removing 3 chute scoop and platic ramp.

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