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(Topic ID: 278096)

Harlem Globetrotters Globe Saucer Solenoid Not Firing


By thrillhousejames

29 days ago



Topic Stats

  • 20 posts
  • 5 Pinsiders participating
  • Latest reply 22 days ago by Quench
  • No one calls this topic a favorite

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#1 29 days ago

Hi everyone, I recently picked up a HG pin which is mostly working...except one thing. Initially, the globe saucer would kick the ball out about 70 percent of the time, then 0 percent of the time, then I thought I fixed it by cleaning the plunger and replacing the coil sleeve...but we're back to it not firing now.

So far, I have verified that the coil has continuity to the solenoid driver board. Verifed both test points on the solenoid driver board are giving 5v (Sitting at about 5.17v). I have changed the transistor on Q12 thinking that may be the issue as well, but no dice. I have changed the coil with a verified working coil as well (correct part number, don't worry!) At this point I'm not sure what could be causing this coil not to fire. I plan to redo the pin header and connections at some point soon, but as I said, currently the wiring has continuity to the solenoid driver. Literally everything else on the machine works great, except that the globe saucer coil stopped firing. Any help is appreciated, thanks Pinside!

#2 29 days ago

Is the switch working? Does it fire in test?

#3 29 days ago
Quoted from Jahkub:

Is the switch working? Does it fire in test?

Yes, switch registers, chimes and awards points.

EDIT: Solenoid does not fire in test

#5 29 days ago
Quoted from thrillhousejames:

Yes, switch registers, chimes and awards points.
EDIT: Solenoid does not fire in test

Broken wire at coil lug? You have a DMM? Do you get power at the coil? Like the other poster asked, does it work in coil test?

#6 29 days ago

Thanks for the suggestion, I'll check on it when I get back home this evening

Quoted from RC_like_the_cola:

Broken wire at coil lug? You have a DMM? Do you get power at the coil? Like the other poster asked, does it work in coil test?

Yes I have a DMM. Coil is getting power at both lugs, measuring 15 ohms across the lugs. Does not fire in coil test

#7 29 days ago

Diode test from base of Q12 to pin 9 of U3 measures 0.56v, base of Q12 to pin 10 of U3 measures 0.85v

These are the same measurements I get from the transistors of verified working coils that also connect to U3

Measuring 0.695v when I do the diode test on U3 from pin 9 to 10, and pin 10 to pin 15

#8 29 days ago

So red lead on pin 10, then measuring 9 and 15?

#9 28 days ago
Quoted from Jahkub:

So red lead on pin 10, then measuring 9 and 15?

Yes, as per that thread

#10 28 days ago

I'd say if you can confirm the whole circuit between the coil and the transistors, then keep moving towards the mpu. Maybe even try swapping U10 and U11 on the mpu to start. When I fist got my Harlem it had bad pia chips that were causing strange solenoid behaviors.

#11 28 days ago

Does the globe saucer coil activate when you:

1. Hook up a jumper wire to ground and very *briefly* touch the other end on the metal tab of Q12?
2. Hook up a jumper wire to test point TP6 on the solenoid driver board and very *briefly* touch the other end on the base of Q12?
3. Hook up a jumper wire to ground and very *briefly* touch the other end on pin 10 of U3?

#12 28 days ago
Quoted from thrillhousejames:

Hi everyone, I recently picked up a HG pin which is mostly working...except one thing. Initially, the globe saucer would kick the ball out about 70 percent of the time, then 0 percent of the time, then I thought I fixed it by cleaning the plunger and replacing the coil sleeve...but we're back to it not firing now.
So far, I have verified that the coil has continuity to the solenoid driver board. Verifed both test points on the solenoid driver board are giving 5v (Sitting at about 5.17v). I have changed the transistor on Q12 thinking that may be the issue as well, but no dice. I have changed the coil with a verified working coil as well (correct part number, don't worry!) At this point I'm not sure what could be causing this coil not to fire. I plan to redo the pin header and connections at some point soon, but as I said, currently the wiring has continuity to the solenoid driver. Literally everything else on the machine works great, except that the globe saucer coil stopped firing. Any help is appreciated, thanks Pinside!

Have you checked and/or changed the diode and resistor for this Q12 circuit on the SDB?

#13 28 days ago
Quoted from Quench:

Does the globe saucer coil activate when you:
1. Hook up a jumper wire to ground and very *briefly* touch the other end on the metal tab of Q12?
2. Hook up a jumper wire to test point TP6 on the solenoid driver board and very *briefly* touch the other end on the base of Q12?
3. Hook up a jumper wire to ground and very *briefly* touch the other end pin 10 of U3?

Yes to all three of these questions. Very weird thing happened though. After doing these tests, the coil started firing when I manually trigger the globe saucer switch. That is unexpected and I'm not sure exactly what it means, or if it's just a fluke?

Quoted from Jahkub:

I'd say if you can confirm the whole circuit between the coil and the transistors, then keep moving towards the mpu. Maybe even try swapping U10 and U11 on the mpu to start. When I fist got my Harlem it had bad pia chips that were causing strange solenoid behaviors.

Thank you again, you've been super helpful. Please see my above reply to Quench if you have the time, a new development has occured

Quoted from emsrph:

Have you checked and/or changed the diode and resistor for this Q12 circuit on the SDB?

Tested yes, they check out as far as I can tell. No replacement parts on hand currently

#14 28 days ago

UPDATE: After it briefly started working, it will no longer trigger the coil when I ground pin 10 of U3. Suspect the IC was working intermittently while failing. Will swap U3 and U4 and report back

#15 28 days ago
Quoted from thrillhousejames:

Will swap U3 and U4 and report back

Suspect diode CR12 first even if it tests ok at the moment you test it with your meter. They sometimes become "lazy" and intermittently stop conducting.
U3 failures are usually more catastrophic with locked on coils.

#16 28 days ago
Quoted from Quench:

Suspect diode CR12 first even if it tests ok at the moment you test it with your meter. They sometimes become "lazy" and intermittently stop conducting.
U3 failures are usually more catastrophic with locked on coils.

Thank you for the insight. I went to desolder CR12 to do a temporary swap from CR13, and the diode literally fell apart in my tweezers. Safe to say it wasn't in great shape! I'll go ahead and order more transistor array ICs, diodes, and resistors. Will rebuild that section of the board after the arrival of the parts and update the thread.

#17 28 days ago

For now you can just borrow the diode at CR18 - it's in an unused driver circuit that the game doesn't have any coils attached to.

#18 23 days ago
Quoted from Jahkub:

I'd say if you can confirm the whole circuit between the coil and the transistors, then keep moving towards the mpu. Maybe even try swapping U10 and U11 on the mpu to start. When I fist got my Harlem it had bad pia chips that were causing strange solenoid behaviors.

Diodes replaced, still couldn't get the globe saucer coil to fire. Swapped U10 and U11 and game would not boot up, swapped them back and it still won't boot up. Put new 6821 PIA chips in, and that didn't fix the problem either, so I'm going to check the sockets and most likely replace them. Thanks for your help, I'm sure we will get this running soon!

#19 23 days ago

It's booting up again, going to replace U3 for fun and see how it goes. Curious how I would check to see that it's even getting the signal to fire though, guess I'll hang out with the schematic for awhile lol

#20 22 days ago
Quoted from thrillhousejames:

going to replace U3 for fun and see how it goes. Curious how I would check to see that it's even getting the signal to fire though

Pin 9 of U3 should briefly pulse low to zero volts when the Globe Saucer is being activated - watch it with your multi-meter in solenoid test mode at solenoid #03

What voltages do you measure at: (use the "GND" test point on the solenoid driver board to hook up the black multi-meter lead to)
- pin 14 of U2
- pin 10 of U3
- pin 9 of U3
- non-banded side of diode CR12
- banded side of diode CR12

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