(Topic ID: 320435)

Doctor Who mini playfield is out of sequence

By Tucker46

1 year ago


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  • 15 posts
  • 8 Pinsiders participating
  • Latest reply 1 year ago by SamW
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#1 1 year ago

I have a Doctor Who that i just replaced the mini play field motor. After it was replaced, i started receiving errors that there was no cw movement. I ran the test and both directions worked when tested. When i start a game the play field would start in different positions. Down, mid or up. It wouldn't capture the balls and the lite lock target and center position buttons ( when in the center position at start) all start counting down the expansion factors. I've tested all the switches from the menu and they are working correctly. I'm not sure where to go from here. Does anyone have any ideas.

#2 1 year ago

Lift playfield and look at wires going to motor. There is a red dot on one side of the new motor. That is where the black wire goes. The red wire goes to the other side. I put a new motor in and wired it red to red and had similar problems.

It that is not your problem, then maybe the cam wheel is not locked down with Locktite, and is slipping which is confusing the Optos below the motor. Clean the optos with a q=tip and rubbing alcohol.

Lets hope it is not a bad 10 Opto board sending mixed signals.

#3 1 year ago

Also, I have found that if one of the 5 mushroom button Optos is burnt out, that row of square lights will count down. So if all those Optos are not connected, it would also have the effect of counting all of them down. That is the 12 pin connector that sits below the motor.

#4 1 year ago

What does the visual show on the DMD? Is it not showing the correct position of the Mini-PF in test mode? Could have something as simple as a broken opto wire.

Many things go wrong here, but narrow it down to the simple things like Tophervette suggested.

May want to post in the Doctor Who Forum for a targeted audience.

#5 1 year ago

I removed the MPF, checked the motor wiring and all other wires for any breaks and found nothing. The mushroom buttons and cleaned the optos and led's with alcohol and am still having the problem. On power up the MPF moves up and down a few times then stops, usually in either the middle or upper position before displaying fpr me to see the test report. The report says that there is no CW movement and no CCW movement.

#6 1 year ago

So, we eliminated the easy fixes. Three choices left. Based on price.
1. The Opto pair below the motor is bad. $20
2. The motor board is bad. $100
3. The 10 Opto board is bad. $100

There is a way to test the Optos, listed in the Dr.Who club posts, with a camera. I have never tried that.

A tech with meter could test your boards for a faulty part. Or you could look at both, looking for a burnt component.

The good news is that Marco sells all those parts. Or if you lived close to someone that has similar game or parts, you could swap.

#7 1 year ago

I had a DW long time ago with similar problems , the culprit was a loosen cam wheel on the motor axle.
You will need to open the gearbox and re-solder the cam wheel .

#8 1 year ago

Is the motor correct wired ? You could try to swap (+) and (-) on the motor and see if the errors disappear.

#9 1 year ago

I had the exact problem. Swap the motor wires.

#10 1 year ago

I'm not sure this is a bad motor wiring. Feels more like the opto on the bottom of the MPF. Still unclear the whole picture. Why don't you PM me you're phone number for a call (or facetime) to talk through this. We can report back to document anything significant.

faz

#11 1 year ago

Thanks for all the suggestions. I tried switching the wires and that didn't help. I checked the LED on the motor opto and it did light up but have no idea how to check if its being received correctly. I'll look through the post mentioned and see if there is a way to test the boards.

#12 1 year ago
Quoted from Tucker46:

Thanks for all the suggestions. I tried switching the wires and that didn't help. I checked the LED on the motor opto and it did light up but have no idea how to check if its being received correctly. I'll look through the post mentioned and see if there is a way to test the boards.

Call Faz.

#13 1 year ago

So with the help of Rich Fazio (MPF Master), we were able to solve the problem. It turns out either the emitter or the receiver (not sure which one is which) on the back side wasn't getting completely blocked by the cam (pic 1). The solution was to place a small nylon washer in between the mounting plate and the emitter/receiver (pic 2). No more errors and its working perfectly again. I don't know what could have altered the position of the opto switch when i changed out the motor. Thanks for everyone's help and extra thanks to the "MPF Master".

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#14 1 year ago

This one was definitely tricky. Everything worked just fine as an independent component but the "system" failed.

All the mushrooms worked .. perfect
We tested voltage out of the Bi-Directional board through Test 14 ... perfect
We tested the opto at the base of the game .. perfect (but this was a gross test.. block the beam with a finger).
We compared the diagnostics on the DMD to what was going on .. perfect (until the error at least.. but made it through a few cycles first)

This is a very subtle issue that I've never seen before. The opto was probably always just on the edge of working but replacing the motor shifted it just a hair.. and that was enough.

Very glad to hear it's working again!
faz

2 months later
#15 1 year ago
Quoted from pinball_faz:

This one was definitely tricky. Everything worked just fine as an independent component but the "system" failed.
All the mushrooms worked .. perfect
We tested voltage out of the Bi-Directional board through Test 14 ... perfect
We tested the opto at the base of the game .. perfect (but this was a gross test.. block the beam with a finger).
We compared the diagnostics on the DMD to what was going on .. perfect (until the error at least.. but made it through a few cycles first)
This is a very subtle issue that I've never seen before. The opto was probably always just on the edge of working but replacing the motor shifted it just a hair.. and that was enough.
Very glad to hear it's working again!
faz

OMG. You are a life saver. I had this exact same issue. Added a washer and it's working again. THANK YOU.

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