(Topic ID: 197551)

What could cause no coils to fire besides flippers?


By megalo17

2 years ago



Topic Stats

  • 49 posts
  • 13 Pinsiders participating
  • Latest reply 2 years ago by Quench
  • Topic is favorited by 5 Pinsiders

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Linked Games

  • Stars Stern Electronics, 1978

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There have been 5 images uploaded to this topic. (View topic image gallery).

IMG_0781 (resized).JPG
IMG_1414.gif
IMG_1402c.jpg
Alltek-SDB.jpg
IMG_5725 (resized).PNG

#1 2 years ago

At my wits end...
In a nutshell, Stern Stars, all new boards, all fuses test good, 43V power at all coils. Game will start, however, zero coils will fire besides flippers. All diagnostic LEDs on mpu and driver board are good. I've repinned all connectors. What am I missing? I've owned it for 2 years and played it zero times... I've verified all wiring going into connectors is correct with schematic and a working pin. Any help really appreciated.

#2 2 years ago

100% guarantee it's the 1A fuse under the playfield between the flippers that is blown.

Make sure you replace it with a 1A slow blow fuse, don't substitute in 2A or 3A or 5A. These will sometimes just go bad from flipper vibration as that's where it's located. If it blows immediately after installing, then you have other issues.

#3 2 years ago
Quoted from schudel5:

100% guarantee it's the 1A fuse under the playfield between the flippers that is blown.

Or the fuseholder has gone bad (tarnished, broken clip, weak clip).

#4 2 years ago
Quoted from megalo17:

In a nutshell, Stern Stars, all new boards, all fuses test good, 43V power at all coils.

So you've got power at all the coils.. The problem might be up stream. Try testing the ground path to the coils from the Solenoid Driver Board (SDB).

Using a piece of wire, very briefly ground the metal tab of the solenoid driver transistors on the SDB to see if its respective coil activates? Grounding the metal tab of transistor:
Q1 should activate the 10 point chime coil
Q4 should activate the Outhole coil
Q12 should activate the top Pop Bumper coil
Q13 should activate the left Drop Target reset

#5 2 years ago

2nd the vote on fuse under playfield. Fuse and holder can look good and be bad. If so, easy fix. Good luck...........

#6 2 years ago
Quoted from schudel5:

100% guarantee it's the 1A fuse under the playfield between the flippers that is blown.
Make sure you replace it with a 1A slow blow fuse, don't substitute in 2A or 3A or 5A. These will sometimes just go bad from flipper vibration as that's where it's located. If it blows immediately after installing, then you have other issues.

I have this exact problem on STARS but it's not the 1A fuse, OR any continuity. No breaks in the daisy chain. It's driving me insane. I even tried jumping over the fuse holder, and jumping power directly from the flipper coils to the other coils. I've also repinned most (but not all) connectors, I'll get the rest this weekend.

Flippers and lock out coil works, nothing else. getting only 17 volts at the flippers (which work perfectly!) and 17 volts at all coils. Can't get them to fire. It's really driving me crazy.

#7 2 years ago
Quoted from Quench:

So you've got power at all the coils.. The problem might be up stream. Try testing the ground path to the coils from the Solenoid Driver Board (SDB).
Using a piece of wire, very briefly ground the metal tab of the solenoid driver transistors on the SDB to see if its respective coil activates? Grounding the metal tab of transistor:
Q1 should activate the 10 point chime coil
Q4 should activate the Outhole coil
Q12 should activate the top Pop Bumper coil
Q13 should activate the left Drop Target reset

I've got the alltek ultimate driver board. Not sure I can short those. I think they're mosfets? I'll look into it.

#8 2 years ago
Quoted from schudel5:

100% guarantee it's the 1A fuse under the playfield between the flippers that is blown.
Make sure you replace it with a 1A slow blow fuse, don't substitute in 2A or 3A or 5A. These will sometimes just go bad from flipper vibration as that's where it's located. If it blows immediately after installing, then you have other issues.

That fuse provides power to the coils, correct? They've all got 43Vdc.

#9 2 years ago

Have you checked your rectifier board? Had a similar issue with my meteor, some of the coils ground connection is on there and not on the SDB.

#10 2 years ago
Quoted from Thrillhouse:

Have you checked your rectifier board? Had a similar issue with my meteor, some of the coils ground connection is on there and not on the SDB.

It's a new board. All voltages good. Continuity from transformer to board terminal is good. All wires verified.

#11 2 years ago

I don't want to pour more money into this by purchasing an alltek driver board tester, but I'm running out of options.

#12 2 years ago

If you go to solenoid test mode (via the test switch inside the coin door), do the Solenoid Diagnostic LEDs on the Alltek board flash/flicker when solenoids are supposed to activate?

Can you tell us what model of MOSFETs are used on this Alltek SDB so we can determine which pin to ground. It looks to me by the board picture in their manual that the transistor metal tab is still the one to ground - but lets make sure first.

If you have a logic probe, does pin 7 of connector J4 at the SDB board pulse low when solenoids are supposed to activate?

#13 2 years ago
Quoted from Thrillhouse:

Have you checked your rectifier board? Had a similar issue with my meteor, some of the coils ground connection is on there and not on the SDB.

How did you fix this? Rebuilding the connectors? Or were there rectifier board issues?

Me and the OP are trying to figure out the same issue on the same game.

#14 2 years ago

I am no super tech but I believe that the issue is with a broken wire in the daisy chain either on the playfield coils or switches. The OP should be able to manually fire the coils with an alligator clip and doesnt need a test board. Make sure that the ground wire that runs from the cab to the back box has been attached, its easy to miss with these old games that need to have the head removed when breaking them down. With the game in attract mode attach one end of a alligator clip to the ground in the back box and touch the other end to any of the pop or sling transistors, Q9 will be the easiest to see for the pop bumper

Quoted from Quench:Can you tell us what model of MOSFETs are used on this Alltek SDB so we can determine which pin to ground.
. If the coil does not fire then do a continuity check from the common coil wire (Yellow on Stars?) to the back box connector. If the coil does fire then do a switch test. Push the switches on the right sling closed and begin the test. If the test shows #36 closed then I would refer to what Quench has mentioned above
Quoted from Quench:If you have a logic probe, does pin 7 of connector J4 at the SDB board pulse low when solenoids are supposed to activate?

.

Quoted from CrazyLevi:

How did you fix this? Rebuilding the connectors? Or were there rectifier board issues?
Me and the OP are trying to figure out the same issue on the same game.

I didn't realize the OP had already replaced the rectifier board and should disregard my post. In my case I always start with replacing the rectifier boards and redoing the connectors as they are cheap and easy to repin on these SS. Getting the playfield coils to fire was actually a secondary bonus of what I was trying to track down at the time.

#15 2 years ago
Quoted from CrazyLevi:

How did you fix this? Rebuilding the connectors? Or were there rectifier board issues?
Me and the OP are trying to figure out the same issue on the same game.

I also had a similar issue, it was caused by my poor "repinning" of the solenoid ground return on the SDB. I think it's on J3, one of the .156 connectors (check schematic for Solenoid GND). Once I located the poorly pinned wire, the solenoids returned. Check that you have continuity from the pin, along the wire to the playfield as mentioned in the post above.

#16 2 years ago

Thanks for the tips everyone! Trying to get around to it... and I'm fresh out of pins. Time to order 100!

#17 2 years ago

I haven't pulled the trigger on a logic probe yet, but it's time. Any recommendations for one that won't break the budget?

#18 2 years ago

Here's the mosfet. That's all the data I can find on them.

IMG_5725 (resized).PNG

#19 2 years ago

After doing the solenoid diagnostic only Q19 and 15 fired. I believe it's the flipper and coin lock-out coils. No other diagnostic led's lit. I checked continuity between the ground return on each coil and the pins and they were all less than 1 ohm.

#20 2 years ago

Firstly, what are the solenoid diagnostic LEDS on the Alltek SDB doing in solenoid test mode? They will be telling you if communication from the MPU board to the SDB is working or not.

The MOSFET is a FQB33N10L . Grounding procedure is the same as the normal transistors on factory SDB's. Briefly shorting the upper metal tab part of the MOSFET transistor to ground should activate solenoids. Grounding the metal tab on transistor:
Q1 should activate the 10 point chime coil
Q4 should activate the Outhole coil
Q12 should activate the top Pop Bumper coil
Q13 should activate the left Drop Target reset

#21 2 years ago

The diagnostic leds are only lighting for the two coils. No other diagnostic leds light during the test. Tomorrow, I'll ground the mosfet, attaching an alligator clip to the center prong. I suspect they will all work, since it's a new board and one shouldn't presume multiple failures when troubleshooting. But, we'll see... Thanks again! I can't let this pin own me!

#22 2 years ago
Quoted from megalo17:

The diagnostic leds are only lighting for the two coils.

If the solenoid diagnostic LEDs don't flash for the momentary solenoids, then it probably means there's a communication issue between the MPU board and the SDB. The flipper enable relay and coin lockout coil are considered "continuous coils" and use different signals from the MPU board.

Check that you have proper continuity between MPU connector J4 pin 10 and SDB connector J4 pin 7. A poor connection on this solenoid enable signal can cause none of the momentary solenoids to activate.

#23 2 years ago
Quoted from Quench:

If the solenoid diagnostic LEDs don't flash for the momentary solenoids, then it probably means there's a communication issue between the MPU board and the SDB. The flipper enable relay and coin lockout coil are considered "continuous coils" and use different signals from the MPU board.
Check that you have proper continuity between MPU connector J4 pin 10 and SDB connector J4 pin 7. A poor connection on this solenoid enable signal can cause none of the momentary solenoids to activate.

Yes, I have continuity across that wire. The pins are new and look good. I'll check the mosfets just in case. Any other ideas? Emotional roller coaster...

#24 2 years ago

Mosfet test worked. Q7-10, and Q17 and Q18 are not used, I believe. Every other one fired.

#25 2 years ago

Do you think this could be a board issue? With all the onboard diagnostics, and the game exhibiting the same symptoms that existed before I replaced mpu, solenoid, and power boards, I'm thinking the alltek is fine.

#26 2 years ago

Sorry this is causing a headache for you.

The SDB is not responding to commands from the MPU board to activate solenoids so the first thing to do is make sure the SDB is receiving those command signals. If these signals all test ok, then the Alltek SDB is suspect.

You mentioned the connectors have been re-pinned - are you sure none of the terminal pins accidentally got squashed too much and aren't physically touching the pin on the board? Below I've posted a picture of a connector and how a terminal is gapped too much and not making contact with the board pin.

Grab your mulitmeter and set it to DC voltage. Hook up the black meter lead to ground somewhere.
Start the game and go to the solenoid test mode.

See the picture of the Alltek SDB below - sorry about the poor quality but it's all I can find that's published. To the left of the J4 header connector, you can see traces running from the J4 pins to a tiny black resistor network with tiny legs on its side.

If you follow the pin/signal marked CB2 and put your red meter lead where that signal goes to that black resistor network, you should read 0 volts while in solenoid test mode.
Do the same with the signals marked PB0, PB1, PB2, PB3. Keep your red meter lead on these pins during the solenoid test - when certain solenoids are supposed to activate, some of these signals should briefly change from 5 volts to 0 volts. With these signals you are basically looking for the quick change to 0 volts happening.

I hope this all makes enough sense for you to follow. If not post a nice clear pic of the same area pictured below so I can detail better where to measure.

Alltek-SDB.jpg
IMG_1402c.jpg

#27 2 years ago

Quench, I can't thank you enough for all of your help! It's truly appreciated. If I get this baby working, someone is getting a nice stocking stuffer this year..
With regards to the pin connectors, I don't think any of mine lean all the way over to the opposite wall of the housing. Maybe 50% daylight showing, so I'll address that.
I can follow your directions for measuring the voltage at the resistors. I'll check that tomorrow.
Thanks again!

#28 2 years ago
Quoted from megalo17:

With regards to the pin connectors, I don't think any of mine lean all the way over to the opposite wall of the housing. Maybe 50% daylight showing, so I'll address that.

That's not a good sign. You can try and repair the tension on the terminals for those PB0, PB1, PB2, PB3 and CB2 signals at the SDB and MPU side. See the animated slideshow below:

IMG_1414.gif

#29 2 years ago

I have the exact same problem on the exact same game and I'm also following this thread. Thanks!

I suspect connection error between the boards.

Or maybe it's just a Stars thing and an alltek defect. I've used TWO different alltek MPUs and SDBs so it's likely not defective boards.

#30 2 years ago

I might of missed it but did you do a switch test?
I had a stern melody lane that did the same thing ended up being a tilt switch closed.

#31 2 years ago
Quoted from wdennie:

I might of missed it but did you do a switch test?

The solenoids aren't activating in solenoid test mode, so switches aren't in the equation yet.

#32 2 years ago
Quoted from CrazyLevi:

I have the exact same problem on the exact same game and I'm also following this thread. Thanks!

What's changed on your machine between it working and now not working?

#33 2 years ago
Quoted from Quench:

What's changed on your machine between it working and now not working?

It was never working. Project game. Wouldn't boot when I got it, I have now gotten it to the same spot as the OP.

#34 2 years ago
Quoted from wdennie:

I might of missed it but did you do a switch test?
I had a stern melody lane that did the same thing ended up being a tilt switch closed.

That's interesting. I have a couple non-working switches which are maybe stuck closed? Wasn't bothering tracking down the switch issues till I figured out the bigger solenoid issue. Will look into that.

#35 2 years ago

I just had this exact problem with my Meteor after having it in the light test mode for a good bit. Turned out to be the 1A slo blow. It looked like it was still good but tested bad. Only the flippers, coin door and knocker coils worked.

#36 2 years ago
Quoted from Chalkey:

I just had this exact problem with my Meteor after having it in the light test mode for a good bit. Turned out to be the 1A slo blow. It looked like it was still good but tested bad. Only the flippers, coin door and knocker coils worked.

Correct me if I'm wrong, but that fuse supplies power to the solenoids, right? If the coils are getting good 43Vdc then I can rule that out. Unless it's a return fuse? I'm sorry, I've got a junior level understanding of schematics, but these drawings give me fits!

#37 2 years ago

Quench, the terminal voltages at the resistor bank did drain from the 5Vdc during the solenoid test. It almost seemed like they would pulse down a couple times during one test sequence, but the lead may have been touching two points. Those points are super tiny!
The connector pins actually look similar to yours. Bad memory... Great picture, btw. Those pins are tiny.

#38 2 years ago
Quoted from megalo17:

Correct me if I'm wrong, but that fuse supplies power to the solenoids, right? If the coils are getting good 43Vdc then I can rule that out. Unless it's a return fuse?

I don't know what it's doing, I just happened to have the same (or similar) symptoms at the same time this thread was up and the fuse was what did it for me. So I was just kind of saying thanks to the people that mentioned the fuse and making sure you checked the fuse (and the wiring on each end, etc).

#39 2 years ago
Quoted from megalo17:

Correct me if I'm wrong, but that fuse supplies power to the solenoids, right? If the coils are getting good 43Vdc then I can rule that out.

Yes that playfield fuse is for the solenoid power after the flippers. The flippers are not fused by that particular fuse. If you're reading 43VDC at the playfield coils, then this fuse should be ok. Plus this further verifies it:

Quoted from megalo17:

Mosfet test worked. Q7-10, and Q17 and Q18 are not used, I believe. Every other one fired.

By this I take it you already tested grounding the MOSFET metal tabs to activate solenoids and they each fired right? That tells you the playfield solenoids definitely have power and grounding through the SDB is ok.

We just need to sort out why the SDB isn't receiving/responding to commands.

Quoted from megalo17:

the terminal voltages at the resistor bank did drain from the 5Vdc during the solenoid test. It almost seemed like they would pulse down a couple times during one test sequence

Ok, if you're willing to try this we can manually command the SDB logics to activate solenoids - this will tell us if the SDB is working or not:
Machine OFF. Disconnect the J4 connector from the SDB and leave it disconnected.
Hook up a wire to the SDB J4 header pin 7 - the pin marked CB2 (use an alligator clip if you have them and make sure it doesn't short to an adjacent pin). We'll call this the ACT wire.
Hook up another wire to ground - we'll call this the GND wire.
Power on the game and go to solenoid test mode.
Connect the other end of the ACT wire to ground so the J4 pin 7 signal (CB2) is now grounded.
a1) Very briefly touch the other end of the GND wire onto pin 6 (signal PB0) of the SDB J4 header.
a2) Does the left slingshot activate?
b1) Very briefly touch the other end of the GND wire onto pin 5 (signal PB1) of the SDB J4 header.
b2) Does the right slingshot activate?

#40 2 years ago
Quoted from Quench:

By this I take it you already tested grounding the MOSFET metal tabs to activate solenoids and they each fired right? That tells you the playfield solenoids definitely have power and grounding through the SDB is ok.
We just need to sort out why the SDB isn't receiving/responding to commands.

Yep, they all fired when I grounded the MOSFET.

Quoted from Quench:

OPQuoted from megalo17:the terminal voltages at the resistor bank did drain from the 5Vdc during the solenoid test. It almost seemed like they would pulse down a couple times during one test sequence

I'll give that a shot after work. Thanks again!

#41 2 years ago

I had a similar issue on an Eight Ball Deluxe with a new Alltek MPU. Re-seating the socketed chips on the Alltek MPU resolved it (credit to pinballninja who solved it).

#42 2 years ago

IMG_0781 (resized).JPG

#43 2 years ago
Quoted from michiganpinball:

I had a similar issue on an Eight Ball Deluxe with a new Alltek MPU. Re-seating the socketed chips on the Alltek MPU resolved it (credit to pinballninja who solved it).

Seems like a smoking gun to me! U2 chip. I've never removed any of these IC's before. Fingers crossed!

#44 2 years ago

WOW! That was it... Pretty emotional find for me. Happy and pissed at the same time! I can't thank you guys enough for the replys and persistence. Lesson learned. An arrival inspection will occur from now on. BTW, with sufficient light and possible some low level magnification, I could've identified this without removing the IC's. Thanks again! Case closed.

#45 2 years ago
Quoted from Quench:

If the solenoid diagnostic LEDs don't flash for the momentary solenoids, then it probably means there's a communication issue between the MPU board and the SDB. The flipper enable relay and coin lockout coil are considered "continuous coils" and use different signals from the MPU board.
Check that you have proper continuity between MPU connector J4 pin 10 and SDB connector J4 pin 7. A poor connection on this solenoid enable signal can cause none of the momentary solenoids to activate.

Are you sure this is correct?

I have no wire at mpu j4 pin 10. The mustard and red wire that is at j47 on the sdb is at mpu j4 pin 9.

There is indeed continuity. But if it's pinned one off at the mpu that would certainly explain my issue.

#46 2 years ago

That was indeed the issue.

Two happy Stars owners in this thread now.

Thanks for the help everyone especially quench!

#47 2 years ago

That's great. I followed the thread and it's great that you guys both found two different causes to an identical problem. Thanks for documenting. Seems that it could definitely happen to all other classic Sterns as well.

#49 2 years ago
Quoted from megalo17:

Seems like a smoking gun to me! U2 chip....
WOW! That was it...

Wow indeed! That bent pin (pin 19 of U2) is the source of the solenoid enable signal from the MPU board and goes to the SDB connector J4 pin 7 (marked CB2 mentioned above).
Great find and glad you're up and running!
Credit to michiganpinball who prompted you to check the socketed chips on the MPU board.

Quoted from CrazyLevi:

That was indeed the issue. Two happy Stars owners in this thread now.

Excellent stuff!

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