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(Topic ID: 262823)

Silverball Mania no coils fire


By msarac

7 months ago



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  • 17 posts
  • 8 Pinsiders participating
  • Latest reply 6 months ago by Atari_Daze
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#1 7 months ago

Just finished reassembling a project Silverball Mania and amazingly it booted right up on the first try. Apart from some switch issues, the game started, flippers work, and scored as expected, but the only coil that would fire was the right pop. Didn't work in game or in test. After testing a few things, I grounded each coil's transistor and they all fired fine. I put the ball back and hit start for the hell of it, and all of a sudden every coil worked! I probably played 30 games trying to adjust everything, then just like that they all went dead again.

Flippers still work fine, but the only coils I hear in test are the coin lockout and a relay in the backbox.

I have 45v at every coil, and every coil will fire when directly grounded to braid. Every coil will fire when its transistor is grounded. Every transistor tests at .42 or .47

F4 tests good out of its clip. The two fuses under the playfield were 3A so I replaced them with 1A and watched when i powered up. Didn't blow either.

I've re-seated all the connectors several times while pulling the boards to look for obvious broken traces or cold joints, and it all looks pretty clean. The fact they all came and went at the same time has me thinking logic issue somewhere, but not sure where to look at this point?

#2 7 months ago

The small jumper on J3 that goes from pin 13 to 25 is a likely culprit - it provides the logic voltage to the solenoid driver board itself (there was no trace directly to it according to bigal56 due to RF testing or safety testing when it was designed). So this single wire jumper is a weak point in the design.

The pins might need to be replaced or it could just be a bad wire, the headers might need attention as well.

#3 7 months ago

Also check the "SOl/SND BANK SELECT" signal that goes from MPU J4 to Driver J4. This signal should be LOW when solenoids are playing and high when sounds are playing.

#4 7 months ago

Slochar, that jumper is present and I have continuity across those pins. I also see the expected 5v at TP3.

Barakandl, that answer was WAY past my skill set! Put it this way, I did just dig out the logic probe I bought but never opened!

So it looks like the black clip to ground, the red on 5v? Which I can get from TP3 on the driver board correct? Set probe to TTL or CMOS? From there, which pin(s) am I probing on those J4s, and I'm guessing put the game into solenoid test mode while I'm doing this?

Appreciate the help guys!

#5 7 months ago

You had coils working, and then they went dead. Start with the connectors, specifically J4 on the MPU. The connectors are 40 years old and way past their rated duty by now.

#6 7 months ago

Seems odd all but one go dead. Since they work when you manually ground them it's not a power issue. I'm with Xenon. a connection problem with the MPU or SD board momentary address lines is most likely the issue.

#7 7 months ago
Quoted from msarac:

Slochar, that jumper is present and I have continuity across those pins. I also see the expected 5v at TP3.
Barakandl, that answer was WAY past my skill set! Put it this way, I did just dig out the logic probe I bought but never opened!
So it looks like the black clip to ground, the red on 5v? Which I can get from TP3 on the driver board correct? Set probe to TTL or CMOS? From there, which pin(s) am I probing on those J4s, and I'm guessing put the game into solenoid test mode while I'm doing this?
Appreciate the help guys!

Probe red on +5v. Probe black on Ground.

When in solenoid test check the LOW is lit at driver J4 Pin 7 / Driver U2 Pin 19.

When in sound test check the driver J4 Pin 7 / Driver U2 Pin 19 is HIGH with brief pulses.

You can also check the Driver U2 A B C D labeled pins change from HIGH / LOW on the probe during solenoid test. Each one should move to low at some point during solenoid test. If one is always high that will cause wrong/no solenoids.
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Seems like this problem comes up a lot and almost always related to connectors from MPU J4 to Driver J4.

#8 6 months ago

I would look for a broken wire at the coils. The power wire is piggy backed between coils. If one end comes off, all in the chain stop working.

#9 6 months ago

I still have 45v at all the coils, and they all work when their transistors are grounded so I think power is good.

Thanks for the details on the logic probe barakandl - all of those tests came back as expected. Driver J4-7 and U2-19 were low during solenoid test, high during sound test, and U2 20-23 all went HIGH to LOW during solenoid test.

I replaced the pins and headers on MPU-J4 and Driver-J4, and confirmed I didn't bridge any two pins that shouldn't be. Also had good continuity on the connectors between those two plugs. It still won't fire.

I noticed the driver board is not Bally but a Stern SDU-100 (10-24-78 Rev C). Assuming that's fine since those solenoids did work for a bit. I do have an Eight Ball Deluxe with the Bally AS-2518-22 driver board that works great - could I swap that into SBM to test? Figure if that works then the problem is somewhere on the driver board...

#10 6 months ago
Quoted from msarac:

I still have 45v at all the coils, and they all work when their transistors are grounded so I think power is good.
Thanks for the details on the logic probe barakandl - all of those tests came back as expected. Driver J4-7 and U2-19 were low during solenoid test, high during sound test, and U2 20-23 all went HIGH to LOW during solenoid test.
I replaced the pins and headers on MPU-J4 and Driver-J4, and confirmed I didn't bridge any two pins that shouldn't be. Also had good continuity on the connectors between those two plugs. It still won't fire.
I noticed the driver board is not Bally but a Stern SDU-100 (10-24-78 Rev C). Assuming that's fine since those solenoids did work for a bit. I do have an Eight Ball Deluxe with the Bally AS-2518-22 driver board that works great - could I swap that into SBM to test? Figure if that works then the problem is somewhere on the driver board...

you can try the eight ball deluxe driver board. all the bally / stern games driver boards are interchangeable except for maybe some four flipper games need thicker tracks around the relay.

Next thing you can check with a probe is the driver board U2 74154 outputs. Put the game in solenoid test and watch a used output of the 74154 chip. Like U2 P9 for the right pop bumper. During solenoid test U2 P9 should sit high and briefly pulse low when the pop bumper should fire. You can check that output and a few others to determine if the decoded solenoid signal logic is working OK.

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#11 6 months ago

I installed the EBD driver board and all the coils work, so definitely something on the board itself. I'll replace the rest of the headers while the original board is out and keep testing once it's reinstalled. I appreciate being able to add the logic probe to my bag of trouble shooting tools, so thanks again for the hand holding!

2 weeks later
#12 6 months ago

The silver lining in all this social-distancing is that I finally found the time to get back to this one! I used the good SDB to get this pin dialed in and working 100%, so that's a pretty good baseline for going forward.

I replaced all the headers on the original board, and when reinstalled it's right back to the same symptoms - no coils. The outputs on U2 look fine as pins 7-11,13-15 all sit high and pulse low during solenoid test.

#13 6 months ago

So I've replaced all the headers and pins with Trifurcons on the MPU, Stern SDB, and Rectifier boards, also I've done the ground mods and tied TP1 and TP3 together. That got everything working except the left sling and, intermittently, the right pop bumper.

Both of those still fire when the transistor is grounded so it must be upstream from that, right? Now if I'm reading these schematics right (huge IF), the signal to fire the left sling looks like this:

U2-11 - goes low during solenoid test
R67 - tests good
U3-2 - goes high during solenoid test, and all of the transistors on U3 test good.
CR9 - tests good
Q9 - tests good (brand new TIP102 for shits and giggles)
J5-9 - re-pinned a second time - see above.

The switches register in test, and the sounds and scores are there in gameplay, just no coil action on either.

Just to double check, I reinstalled the Bally SDB and everything works perfectly. What am I missing on the Stern board? I assume the schematics are valid for both boards?

Oh just remembered to check C23, which is coming in at .300vac. Pretty sure that ain't good! Could that be the root cause of these two not working correctly or at all?

#14 6 months ago
Quoted from msarac:

That got everything working except the left sling and, intermittently, the right pop bumper.
Both of those still fire when the transistor is grounded so it must be upstream from that, right?

Grounding the metal tab of the transistor does not test the transistor - all it does is test continuity from the transistor to the coil.

Quoted from msarac:

U3-2 - goes high during solenoid test, and all of the transistors on U3 test good.
CR9 - tests good
Q9 - tests good (brand new TIP102 for shits and giggles)

If SDB U3-2 is going high during solenoid test, the problem can only be diode CR9 or transistor Q9 or a trace connection between them.

Grab a jumper wire and hook one end up to test point TP6 on the solenoid driver board. Very briefly touch the other end of the jumper wire on the banded side of diode CR9. If the left slingshot activates, diode CR9 is suspect. If it doesn't your problem is around transistor Q9. Make sure there's no damaged traces to it from previous repairs.

Intermittent coil drive issues I've seen have always been a weak failure of the diode in the pre-drive circuit. So for your right pop bumper that activates intermittently replace diode CR8 and see how it goes.

Quoted from msarac:

Oh just remembered to check C23, which is coming in at .300vac. Pretty sure that ain't good! Could that be the root cause of these two not working correctly or at all?

Capacitor C23 isn't your problem, it'll typically have between 0.2V and 0.3V ripple across it.

#15 6 months ago
Quoted from slochar:

The small jumper on J3 that goes from pin 13 to 25 is a likely culprit .

Did you ever verify this and reflow the solder to the pins?

#16 6 months ago
Quoted from BigAl56:

Did you ever verify this and reflow the solder to the pins?

I did. The wire checked out and later on I replaced J3's header, pins and connector. Just curious though, the TP1 to TP3 jumper mod just reduces the strain on those pins; it doesn't eliminate the need for the wire between 13 and 25, right?

Quoted from Quench:

...Very briefly touch the other end of the jumper wire on the banded side of diode CR9. If the left slingshot activates, diode CR9 is suspect. If it doesn't your problem is around transistor Q9.

IT'S ALIVE!!! This is the nugget of knowledge I've been searching for - I wasn't aware of that trick to test the diode. It was reading .48 just like the other diodes in that area so I assumed it was good. Replaced CR8 and CR9 and both the sling and pop are working great now! I guess the moral of the story is you can't always trust the multimeter test with diodes?

I learned a ton troubleshooting this one, so thanks again to everyone who contributed!

#17 6 months ago
Quoted from msarac:

I wasn't aware of that trick to test the diode. It was reading .48 just like the other diodes in that area so I assumed it was good. Replaced CR8 and CR9 and both the sling and pop are working great now! I guess the moral of the story is you can't always trust the multimeter test with diodes?

You cannot test a diode in a circuit, only by itself.
Glad you got it figured out, I know what a relief that is.

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