Doctor Who mini-playfield gearbox/motor

(Topic ID: 219162)

Doctor Who mini-playfield gearbox/motor


By chaos19

3 months ago



Topic Stats

  • 18 posts
  • 8 Pinsiders participating
  • Latest reply 18 hours ago by pinball_faz
  • No one calls this topic a favorite

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#1 3 months ago

My dr who mini play doesn't move in play or test mode. I get voltage on the motor on all the ccw and cw tests so I believe its the motor or gearbox or both. I can move the miniplayfield up and down by hand with some strength, does this mean the gearbox is stuffed. If it isn't I'ld like to buy a new 20V DC motor online but I have no idea of the RPM, torque or current. I emailed twice MultiProducts that built the gearboxes for Bally/Williams and they will not send me a reply (probably because I'am not a business). Also how do I unscrew the motor from the gearbox, its not as simple as my Indiana jones. Any info will be much appreciated.

#3 3 months ago

I would start with the bi directional board. There is a capacitor on there that likes to leak, and take out the trace below it.

#4 3 months ago

I started with the bi directional board and checked with my DMM and get +20v to -20v from the motor jumper with all cw & ccw tests as with the pins on the motor itself.

#5 3 months ago

I'm unclear if your motor is working at all. It sounds like you pulled the MPF... pull out the motor/gearbox then pull the motor off the assembly.
Plug the motor in the connector to check the motor. I really doubt the motor is burned out; it really does not get that kind of abuse.

faz

#6 3 months ago

Its the gearbox i'm most worried about, they cost over $200 here in Aus. I read somewhere that if I can move the cam wheel, which happens when I move the mpf up of down by hand (I haven't taken the mpf out yet), then my gearbox is stuffed. I would like a second opinion.

#7 3 months ago

Assuming "stuffed"=="not awesome"... and yea, probably is.

I'd be happy to do a Facetime/Tango chat if you want to talk through it?
faz

EDIT: Isn't it 3:00am in AUS?

3 months later
#8 4 days ago

I wish to bump this and say that if you hear some gear noises but the axle doesn't turn means your gear box most definitely is "stuffed." I had mine go out, and it's pretty obvious. It goes up and then just doesn't, yet the motor is spinning and (some) of the gears are turning, yet the axle on the opposite side isn't spinning... it's doomed.

#9 4 days ago

Pinball Resource may have one or rebuild for you.

#10 4 days ago

To test the motor.. remove it from the machine and attach the leads to a battery. Ive seen a 9 volt battery used most often.

#11 4 days ago
Quoted from yellowghost:

To test the motor.. remove it from the machine and attach the leads to a battery. Ive seen a 9 volt battery used most often.

I've done that too, but it doesnt always indicate an issue. You're gear box can be going out and yet will still pass this test.

#12 3 days ago
Quoted from jorant:

I've done that too, but it doesnt always indicate an issue. You're gear box can be going out and yet will still pass this test.

Keep in mind that the game powers that motor with 11V more than the 9 volt battery, so if there is a problem with the gears, it should be exposed by this. Many people seem to disassemble the gearbox to “fix” a problem that isn’t even there. In my case, the motor wasn’t being given enough power while in the game because I had lost one of the -2- wires which are feeding the motor

#13 3 days ago
Quoted from Rdoyle1978:

Keep in mind that the game powers that motor with 11V more than the 9 volt battery, so if there is a problem with the gears, it should be exposed by this. Many people seem to disassemble the gearbox to “fix” a problem that isn’t even there. In my case, the motor wasn’t being given enough power while in the game because I had lost one of the -2- wires which are feeding the motor

If you lost one of the two wires, you won't just get weak power, you get NO power.

#14 3 days ago
Quoted from jorant:

If you lost one of the two wires, you won't just get weak power, you get NO power.

Not 1 wire to the motor, there is a flasher (I think it’s the doctor 5 flasher) that the mini play field power also runs through - in my case, there was a connector that had 1 hot wire from the harness and 1 hot wire from that flasher which joined in the connector. The connector (if I am remembering correctly) is a 2-pin molex which then connects to the motor

#15 3 days ago
Quoted from Rdoyle1978:

Not 1 wire to the motor, there is a flasher (I think it’s the doctor 5 flasher) that the mini play field power also runs through - in my case, there was a connector that had 1 hot wire from the harness and 1 hot wire from that flasher which joined in the connector. The connector (if I am remembering correctly) is a 2-pin molex which then connects to the motor

There is only one set of wires feeding the motor power. The flasher can be totally disconnected and not harm the performance of the playfield.

#16 3 days ago
Quoted from jorant:

There is only one set of wires feeding the motor power. The flasher can be totally disconnected and not harm the performance of the playfield.

yup... it's a DC motor. This is the one time where in "sci-fi" terms... "Reversing The Polarity" actually does something. -12V or +12V causes the MPF to move CW or CCW.

faz

#17 1 day ago
Quoted from pinball_faz:

yup... it's a DC motor. This is the one time where in "sci-fi" terms... "Reversing The Polarity" actually does something. -12V or +12V causes the MPF to move CW or CCW.
faz

I wonder if mine was wired incorrectly? That is pretty bizarre

#18 18 hours ago
Quoted from Rdoyle1978:

I wonder if mine was wired incorrectly? That is pretty bizarre

Whoops... sorry.. I misstated something. The voltage is +/- 20V. and I'm not illustrating which voltage drives CW/CCW.. I don't remember. The important thing is that it's just a simple DC motor.

faz

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