Nine Ball
Stern Electronics, 1980You're currently viewing posts by Pinsider Barakawins1.
Click here to go back to viewing the entire thread.
I'm having a problem with the left ball lock. Once the ball enters the saucer hole, the game stops. The next ball doesn't eject and the only way to start the next
ball is to tilt. After tilt, the ball will eject from the saucer. I'm a bit stumped as to why this is happening. Need the schematics to chase this problem down.
Slochar and Quench. Thanks for the info. I'm a little stumped as to what's going on with this machine. I can play the game just fine other than the left ball
lock. Once a ball goes into the ball lock it never ejects, nor does the ball into the shooter lane. If I remove the ball from the lock saucer and place it in the
ball trough, it doesn't end the ball either. Any ideas? Maybe one of you have a photo of the diodes on the ball trough microswitches? I'm wondering if maybe the
diodes on these switches are not installed correctly.
Also if your big drop target bank has problems, balls will get stuck in that lock - it MUST see the "current ball" (blinking light) target go down (go from open switch to closed switch) before it will kick the ball out.
Hmmmm.. Based on what you're saying here.. I'm suspect that it has to do with a diode on one of the switches on the long target bank. I had a problem
wherein drop target 8 would fall as soon as I put the game on. I removed the targets and reinstalled. Now 8 is fine. No problems. Maybe something was
shorting against it.
Now, if the ball is locked in the saucer and I manually knock targets down, the ball will kick out. I think you're onto something here. Maybe one of the
diodes on the back of the switch stack for the drops is bad and it's not seeing it during game play. Crazy thing is there are no switch errors in switch test.
Dropping targets one by one they all register. The ball lock registers too. Something is just amiss and it's driving me nuts.
Update: I've managed to isolate this issue to a mis-wire by the prior owner at the left slingshot. If anyone has wiring photos for the two left slingshot switches
under the playfield that would be fantastic. I need to see which lugs the .05uf capacitor attaches to, Which lugs the diode attaches to and there is a white/brown wire and white/yellow wire which also attaches to the lugs. Thanks in advance. This should fix it all.
Quoted from slochar:Even if this fixes your issue I'm going to move forward with the rom deep-dive and make a run at the core issues with the switch handling. I know Oliver did this years ago, but that fix needs some kind of rom expander to work. I'll see if I can shoehorn it into the normal rom footprint and take a different pass at it.
very cool. I'll test it out.
Quoted from Quench:Yes, diode orientation, capacitor and white-yellow wire locations look correct.
Thanks for that info!
So, tested all diodes in the row and column for the left ball lock. All are fine. I'm starting to wonder if a diode for some reason only fails under load. Before I do,
I'm going to compare my wiring and diode orientation at my friend's house who has a 9 ball. I'll keep updating. Along with the ball lock problem, seems my left
slingshot is triggered by the left middle ball lock switch. Pressing down on this switch will trigger the left slingshot and sometimes the pop bumper.
All switches report correct numbers throughout. This is frustrating. Any other ideas? I already checked all the diodes out of circuit as well. In switch test I shorted
the contacts before the diode and was able to get the correct numbers displayed as well. I'm starting to think maybe this switch is just bad and I need to replace
it. I did a continuity check on it with a meter and when contacts touch it beeps so I'm a bit stumped
Quoted from Quench:In game mode, does the ball get stuck in the left lane saucer even when ball capture isn't lit? i.e. when it's not supposed to be locking the ball?
Yes. It gets stuck in the saucer even when capture is not lit.
What happens in game over mode if you take a ball from the outhole and roll it into the left lane saucer? Does the game kick the ball straight out? it's supposed to, in order to make sure all balls are back in the outhole trough area and ready for new game. Or does the ball just sit in the left lane saucer?
Yes in game over mode, the ball gets kicked out from the saucer and into the trough as it should.
The odd thing is that when the ball locks in the saucer, I can manually score all targets, slingshots, etc... If I pick the ball up out of the saucer and place
it into the ball trough, nothing happens. The next ball won't kick out unless I tilt the game.
Here's a video of my issue. As you'll see the ball lock doesn't eject the ball until I drop a bunch of targets manually. Then, if I remove the ball from the saucer and
put it in the trough, the next ball doesn't eject unless I tilt the game.
Quoted from Quench:So go into solenoid test mode and check that the drop target release coils for drop targets #7, #6, #5, #4, #3, #2 and #1 are working.
I'll check this tonight. Hopefully you're right! Can't wait to solve this issue.
Quoted from Quench:There's no release coil for drop target #8 so that's normal.
Onto drop target #7. Quickly inspect the drop target mechanism where the #7 coil is to make sure there's no wiring issues.
Next, grab a piece of wire with both ends stripped. Hook one end to ground and *very briefly* touch the other end on the metal tab of driver transistor Q13 on the solenoid driver board. Does the #7 drop target fall? If not, try grounding the metal tab of other transistors i.e. Q14 should make the #6 drop target fall, Q9 for drop target #5 - just so you get a feel for how grounding the transistor metal tabs behave.
Quench.. I did what you said. For Target #7 I grounded the Q13 tab to the ground braid in the cab and target #7 target dropped as did all others. I even changed the leaf switch and diode for the ball lock saucer.. Same result. I checked continuity of the wires going from the target leaf switch up to connector J2 and all is well there too. Maybe tell me if the wiring to target #7 is the same as on your machine? The target to the left is #7
772D1460-3C18-4216-B11B-3EF611FF8361 (resized).jpegThe Law and Quench,
Here's a new video.. I think the problem is with the #7 drop target. I'm not exactly sure what the heck is going on here. When the ball enters the saucer, the
#7 target should automatically drop is what I'm thinking. Mine doesn't. However when I manually hit this target, the game works as it should. The targets drop
and the ball releases from the saucer. Any ideas?
Quoted from Quench:Grab your jumper wire, hook up one end up to test point TP6 on the solenoid driver board. Very briefly touch the other end of the wire on the banded side of diode CR13 on the solenoid driver board - it should be near the Q13 transistor. This will test transistor Q13 itself. What happens? Does that #7 drop coil activate?
Quench, I can rule out a board problem and driver. The mpu I changed to an NVRAM Weebly board. The driver board I changed to a working bally board. Still same
issue. Something is not letting that #7 target drop when the ball locks in the saucer.
Quoted from Quench:Sorry, please do the ground test of driver transistor Q13 on the solenoid driver board as I mentioned back up in post #64 and let me know what happens. For some reason I thought you already did it.
This is not a switch/MPU board issue.
Yes I grounded switch Q13 and the #7 target dropped.
Quoted from Quench:Now go and do the jumper test I mentioned in post #71
Target 7 drops
Quench it's not the mpu or the driver board. I changed the mpu and the driver board to known working boards. The boards are working in other machines flawlessly. I'm thinking this is a bad diode on the switch matrix somewhere or there's some wire not making good contact.
The issue is definitely isolated to Target #7. I need the schematics to show what's in line with this target. maybe theres a bad diode upstream or downstream. Something is causing the target not to reset when the ball enters the saucer. Not sure how the saucer affects the #7 target sequence.
Quoted from Redketchup:I will study how your drop target bank behave without the ball in the saucer. You need to be sure it’s working ok there. I made a little video how mine work
Redketchup. Thanks for posting your vid. My targets appear to work like yours do with the ball not in the saucer. It's when the ball is in the saucer that it causes
the targets not to drop normally. Only target #7 causes them to reset and the ball to exit ball lock. I changed the diode on the #7 switch already and no difference.
Quench, I thought about what you said in terms of the Bally board and some transistors not being used. I'm not sure what game it came from. I had it as a spare working board. I put the original Stern driver board back in the game and now the 7 drop falls as it should when ball enters the saucer. It still doesn't pop out as the symptom moved to target #4. If this target is required to fall during the drop sequence, the ball doesn't launch from the saucer. If I knock down target 4 manually, the ball ejects.
I'm going to dive into this later tonight.. I'm glad I swapped driver boards. Thank you for making that comment. It made think about it. I have to check the
transistor that drives that #4 drop and it's pre driver chip. I think this may do it. So I guess not all bally driver boards are compatible with this machine.
Small update.. I grounded the Q10 Transistor tab for target #4. It was dropping but intermittent. Then fully stopped dropping. I suspect a bad Tip102 on that
target so I'll check into it later. Also need to see which pre-driver chip controls this target just in case so I can replace it. I'm getting close.
Quoted from TheLaw:Duh duh duuuuuh. Whelp shorting Q13 didn't work for me which means it's a coil issue. Ah shit i gotta get into that goddamn drop housing. Oh boy.
Or, you may need to just change that transistor. Test the transistor Q13 in diode test. If this transistor is bad the target won't drop.
Quoted from Quench:Ok, next grab your jumper wire and connect one end to ground then very briefly and carefully touch the other end on pin 11 of the U3 chip on the solenoid driver board. If you're not sure which is pin 11 of U3 then please post a picture of your solenoid driver board so I can point to it.
Quench.. On the bally board driver board I did as you said as well. I grounded pin 11 at U3 and target #7 didn't drop. So I'm guessing this pre-driver is bad on this board as well?
Fixed!!!
Here are the fixes.. I had two driver boards. Both had issues.. First, we'll talk about drop target #7 not dropping when the ball lands in the left ball lock. The fix for
this, believe it or not, bad solder joints at connector J5 lower right. I started flexing the board and the game would periodically work. Ugh!!!!!
Stern MPU - Drop Target #4 would not drop when ball lands in left ball lock. Fix.. Capacitor C5 shorted. Changed Cap and all is well with driver board #2.
Game plays fun and fast now. Lots of thanks to Quench, Slochar and all fellow pinsiders for helping out on this one. Now I know the left ball lock is fully dependant
on drop target sequencing. Especially starting with drop 7.
Quoted from TheLaw:Fixed coil, everything fine now. Great work everyone figuring this annoying ass issue out for us and everyone moving forward!
Way to go.. Hey when you get a chance, can you check the ball trough microswitches to see if you have disc caps on them. Also, do you have disc caps on the slingshots?
Interesting. I have caps on ball trough micro switches. Also on slings. My left sling goes off from time to time. I wonder if that’s because of the caps on them
Hmmm. I have one on my pop bumper as well. Does anyone have one on their pop bumper? Dead bumper has one but the above switch matrix shows it should have one.
Quoted from frunch:I had one on the pop bumper and both slings and found they would often fire multiple times or be too sensitive. I would just install caps at the 3 switches called out on the schematic.
Cool.. I'll report back on this tomorrow. Thanks. My left sling goes off more than it needs to and very very sporadically an extra ball shoots out in the shooter lane. I think it's due to these caps.
Actually, if I touch the switch contacts for the slings with my fingers, left or right sling, they snap. I thought that was odd.
Update: So I removed the .05uf 100v caps from the ball trough and left and right sling switches. The game currently only has 1 on the dead bumper, 1 on the 7k/skill shot standing target, and 1 for the upper left loop roll-under gate.
Symptom: left slingshot fire sporadically. No difference.
Ok.. So I seemed to narrow it down to the middle ball lock switch. Seems this switch when depressed multiple times will cause the sporadic left slingshot to engage. I changed the diode on this switch stack, seems no difference. The balls lock up as they should and release as they should otherwise. Anyone know why
this is happening? The left sling switches are gapped with no issues and are far apart. The white brown wire from the middle ball lock switch connects to the left
sling switch stack. Here's a video of what I'm seeing and some pics of the middle ball lock switch and left sling switch wiring.
Video of issue:
1st pic is of middle ball lock wiring
2nd pic is of the left sling wiring
3D102A77-4E94-4E64-8C06-F0216E146A79 (resized).jpeg5C762555-59E6-4832-836A-B7D7E335D502 (resized).jpegYesterday played multiple games. No more issues. Not sure what corrected this problem but it's all gone now.
You're currently viewing posts by Pinsider Barakawins1.
Click here to go back to viewing the entire thread.
Wanna join the discussion? Please sign in to reply to this topic.
Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!
This page was printed from https://pinside.com/pinball/forum/topic/stern-nine-ball-left-ball-lock-schematic-needed?tu=Barakawins1 and we tried optimising it for printing. Some page elements may have been deliberately hidden.
Scan the QR code on the left to jump to the URL this document was printed from.
Woodcliff Lake, NJ