(Topic ID: 234465)

Help: AC/DC Pro all coils stopped working


By gameroompinball

1 year ago



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  • 25 posts
  • 5 Pinsiders participating
  • Latest reply 1 year ago by robertmee
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ACDC Table (resized).jpg
ACDC J7 (resized).jpg

#1 1 year ago

In the middle of a game all my solenoids lost power. I checked the main board and the fuse was blown and the light under it was not lit. I replaced the fuse and the light underneath is still out. After I initiate a new game and check the fuse it is blown. Any ideas?

Thanks

#2 1 year ago

Can you go into test mode and test the coils and see which test blows the fuse? Any playfield fuses blown?

#3 1 year ago

Little confused on the chain of events....when you replaced the fuse, I assume you did so with power off. When you powered back on the game, but NOT start, did the fuse immediately blow again, or did it only blow when you started a new game? If it blew AFTER you started a game, then do exactly what ^he/she said. Instead of starting a game, go into test mode and test each coil until the fuse blows. Then you'll know the culprit. Remember, to test the solenoids, you'll need to have the coin door switch bypassed.

#4 1 year ago

Thanks for the suggestions. I've been away for work and hopefully I'll be able to test it out tonight so I can report back.

#5 1 year ago

Ok here is the latest. Game off. I put a new 5A slo-blow fuse in F10. I turn the game on. Instantly the fuse lights up and blows. Any thoughts?

#6 1 year ago

F10 is for flashers and low powered solenoids. None of the solenoids should activate on power up, so it may be a bad flasher or blown bridge rectifier. Or a shorted transistor for one of the coils.

Put in a new fuse, and Pull Connectors J6 and J7 off the power board.

Power up....If the fuse blows again, possibly bad bridge rectifier.

If the fuse holds, plug in J6 and J7 one at a time, and see which one blows the fuse. Pay attention when you plug J6 in, to see if any flash lamps burn bright before the fuse blows. Or J7, if you hear any coil activate.

Report back.

#7 1 year ago

Ok here is the latest. I followed robertmee suggestions. Power off. Unplugged J6 and J7. Replaced fuse F10. Turned game on. F10 light is on all is good. Next plugged flashers J6 in still good. Finally I plug in J7 low current solenoids. No solenoid activation sounds heard, but F10 fuse lights up orange and blows.
Ok now what’s next?

#8 1 year ago
Quoted from gameroompinball:

Ok here is the latest. I followed robertmee suggestions. Power off. Unplugged J6 and J7. Replaced fuse F10. Turned game on. F10 light is on all is good. Next plugged flashers J6 in still good. Finally I plug in J7 low current solenoids. No solenoid activation sounds heard, but F10 fuse lights up orange and blows.
Ok now what’s next?

Do you have a DVM (Digital Volt Meter)?

#9 1 year ago

Okay, so even though one page of the manual says Solenoids for J7, they are actually flashers on ACDC. I'm sure the manuals are generic across games, so some have solenoids while some have flashers on J7.

In any case, here are the transistors associated with J7, and here are what they control. Visually inspect each one of the flashers and make sure none of the legs of the flashers are touching anything they shouldn't be.

If you don't find anything obvious, we will need a meter for the next step.

ACDC J7 (resized).jpgACDC Table (resized).jpg

#10 1 year ago

Yes I have a DVM. I took a quick look at those and they visually looked clean. Please let me know what to check next.

#11 1 year ago
Quoted from gameroompinball:

Yes I have a DVM. I took a quick look at those and they visually looked clean. Please let me know what to check next.

Remove J7 and power off game. Put your meter on Ohms or Continuity. Put the Black lead of your meter under the ground braid in the backbox. With the red lead, check each pin of the J7 connector that you removed. You might need a paper clip attached to your lead to get into the hole. See if any of the pins reads very low ohms or close to 0, or has direct continuity to ground.

Next, with J7 connector still removed, and a new fuse, power up game to the state that it normally blows the fuse. With Meter on VDC, black lead under ground strap, put red lead on Pin 1 on the board of the J7 header, and you should measure 20VDC or close. Just verifying that you have 20V here first for next test. Now, with red lead on Pin 1, move your black lead and check each of the remaining pins on J7 board. They should all read mV or close to zero. If one of them reads 20V, then the transistor associated with that pin is shorted.

#12 1 year ago

If both of the above checkout, another test, is with game off, J7 removed, DVM on ohms/continuity, put red lead on Pin 1 of the J7 connector, and then check Pins 2 through 10 with the black lead, and see if you have 0 ohms on any pin. This would indicate a shorted socket or flasher bulb.

#13 1 year ago
Quoted from robertmee:

If both of the above checkout, another test, is with game off, J7 removed, DVM on ohms/continuity, put red lead on Pin 1 of the J7 connector, and then check Pins 2 through 10 with the black lead, and see if you have 0 ohms on any pin. This would indicate a shorted socket or flasher bulb.

Since you seem to know about these fuses, any idea whats going on with mine? While playing my ST premium, the upper right flipper suddenly stopped working during gameplay. After checking all the connections, I noticed the fuse under the playfield for this flipper had blown. I replaced the fuse twice and they immediately blew each time when I turned on the game. Any help would be appreciated.

#14 1 year ago
Quoted from newpinbin:

Since you seem to know about these fuses, any idea whats going on with mine? While playing my ST premium, the upper right flipper suddenly stopped working during gameplay. After checking all the connections, I noticed the fuse under the playfield for this flipper had blown. I replaced the fuse twice and they immediately blew each time when I turned on the game. Any help would be appreciated.

I can try to help you, but if you don't mind, start a separate thread. There may be others more knowledgeable on ST that can help too.

#15 1 year ago
Quoted from robertmee:

Remove J7 and power off game. Put your meter on Ohms or Continuity. Put the Black lead of your meter under the ground braid in the backbox. With the red lead, check each pin of the J7 connector that you removed. You might need a paper clip attached to your lead to get into the hole. See if any of the pins reads very low ohms or close to 0, or has direct continuity to ground.
Next, with J7 connector still removed, and a new fuse, power up game to the state that it normally blows the fuse. With Meter on VDC, black lead under ground strap, put red lead on Pin 1 on the board of the J7 header, and you should measure 20VDC or close. Just verifying that you have 20V here first for next test. Now, with red lead on Pin 1, move your black lead and check each of the remaining pins on J7 board. They should all read mV or close to zero. If one of them reads 20V, then the transistor associated with that pin is shorted.

Excellent thank you! When I get home tonight I will try this and report back.

#16 1 year ago
Quoted from newpinbin:

Since you seem to know about these fuses, any idea whats going on with mine? While playing my ST premium, the upper right flipper suddenly stopped working during gameplay. After checking all the connections, I noticed the fuse under the playfield for this flipper had blown. I replaced the fuse twice and they immediately blew each time when I turned on the game. Any help would be appreciated.

For your ST, Id imagine either your transistor went bad, or somehow you lost a diode on the coil or coil is shorted. My money would be on the transistor. Been known to happen even on newer games like this. Any chance it was while you were holding a flipper button in for a while cradling the ball? Failure could happen a number of ways but that seems to do it sometimes. Easy enough to test and replace a transistor on a SAM game. I'm not an experienced tech guy and did this successfully.

I will say though, get some help soldering if it's your first time. Once you put a new transistor in you probably won't have another problem with that flipper as aftermarket transistors from pinball life are more robust.

#17 1 year ago
Quoted from RVApinballer:

For your ST, Id imagine either your transistor went bad, or somehow you lost a diode on the coil or coil is shorted. My money would be on the transistor. Been known to happen even on newer games like this. Any chance it was while you were holding a flipper button in for a while cradling the ball? Failure could happen a number of ways but that seems to do it sometimes. Easy enough to test and replace a transistor on a SAM game. I'm not an experienced tech guy and did this successfully.
I will say though, get some help soldering if it's your first time. Once you put a new transistor in you probably won't have another problem with that flipper as aftermarket transistors from pinball life are more robust.

Yes, I was cradling the ball for about three min. while I was explaining the gameplay to someone. Looks like the transistor Q12 has no power to it. Going to replace the transistor, my first time doing it.

#18 1 year ago
Quoted from RVApinballer:

For your ST, Id imagine either your transistor went bad, or somehow you lost a diode on the coil or coil is shorted. My money would be on the transistor. Been known to happen even on newer games like this. Any chance it was while you were holding a flipper button in for a while cradling the ball? Failure could happen a number of ways but that seems to do it sometimes. Easy enough to test and replace a transistor on a SAM game. I'm not an experienced tech guy and did this successfully.
I will say though, get some help soldering if it's your first time. Once you put a new transistor in you probably won't have another problem with that flipper as aftermarket transistors from pinball life are more robust.

https://pinside.com/pinball/forum/topic/star-trek-pre-fuse-#post-4804684

At least one thing I found out, is the Stern Manual is wrong. Figures.

#19 1 year ago

Thank you all for you help. It was Q12. A new one was just put in and the flipper now works!!!!

#20 1 year ago
Quoted from gameroompinball:

Excellent thank you! When I get home tonight I will try this and report back.

Ok here is the latest. I went thru the first step fine. I put a new 5A fuse in, J7 unplugged, powered on the game. 20V on pin 1. Pins 2,3,4 0V. Pin 6 20v, pins 7, 8, 9, 10 0V. Looks like the culprit is transistor Q20. If you agree. I'll get one this week and install it.

#21 1 year ago

Yep...shorted transistor.

You can double check, with power off and your meter on diode. Remove the connector. Red Meter lead on metal tab. Black meter lead on each outside leg. Should read .6v or so. Swap black to metal tab and red to outer legs...should read open circuit. Check a working transistor to see. Then check the bad one and you'll probably see it fails on one of the legs.

Also be sure to check the coil associated with that transistor and make sure it is not shorted. You don't want to replace the transistor only to have it fail again.

#22 1 year ago

Maybe I'm missing it, but where can I see which coil is associated with it?

#23 1 year ago
Quoted from gameroompinball:

Maybe I'm missing it, but where can I see which coil is associated with it?

In the chart I posted...sorry, it wouldn't be a coil, but left ramp flasher. It's odd that a flasher transistor would fail, unless the flasher bulb/socket shorted.

There's always a chance that Q20 isn't shorted but being turned on by a failed U6, but that would require a logic probe to diagnose. That's why I suggest you diode check the transistor against a working one to see if it differs.

#24 1 year ago

So it appears that the flasher socket is shorted which seems odd

image (resized).jpg
#25 1 year ago

Yep...that's what blew the transistor in the first place, and continued to blow the fuse every time you powered up the game.

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