(Topic ID: 314115)

Bally PB Knocker Stuck On

By GPS

3 months ago


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#1 3 months ago

Hello All

Having an issue with my Bally Playboy and the knocker. I am using an Alltek SDB and according to Dave at Alltek whom I took a video for of the startup, he says it looks good!

What is happening is as soon as you turn the game on, way before it boots, the knocker locks on. I have checked the coil out if the circuit and it is good showing about 5 ohms. I have replaced the diode making sure it went in the same direction as the original. Original was fine but cut it out to test it.

Anyone out there able to shed some light on where I should start checking this issue? Game is really coming along nicely and this is, at this point, the major issue.

I do have a new Alltek light board coming as the MPU are new and the SDB is newer. Just fyi and almost certainly unrelated but just putting it out there.

Thank you as always.

G

#2 3 months ago

I would suspect the output driver (TIP) on the SDB. Check it, and take a close look over the SDB.

#3 3 months ago

Thank you JethroP. I do not have a schematic for that board. Can you or another point me to which transistor it is please?

Thank you

#4 3 months ago
Quoted from GPS:

Thank you JethroP. I do not have a schematic for that board. Can you or another point me to which transistor it is please?
Thank you

http://www.pinballrebel.com/pinball/cards/Tech_Charts/Bally_Playboy_Tech_Chart.pdf
It's Q3

#5 3 months ago

Faultfinding 101

First understand how the coils are operated. Lots of excellent help on PinWiki for this era of machines. I suggest having a good read of that FIRST.

Second narrow down the faulty driver and repair/replace it as required.

Go back to basics and understand HOW the coils are operated in your machine and it will all become clear to you.

Why would you think a coil locking on makes the coil the problem? That is actually the very LAST thing I would look at in this situation.

That's the same as thinking your brake pedal is faulty because the brakes are locked on without realising the handbrake is on.

#6 3 months ago

Check out 5.7.2 and 5.7.3 in the link below. Hope this helps.

https://www.pinwiki.com/wiki/index.php/Bally/Stern#Testing_and_Replacing_Transistors

#7 3 months ago

Yep, most likely a shorted driver transistor. Only other thing I can think of and not very likely would be if the signal wire going to the coil is pinched somewhere and shorting to ground. A bad diode or reverse installed diode can cause the transistor to short due to collapsing magnetic field causing a reverse spike to get back to the board.

#8 3 months ago
Quoted from pins4u:

Faultfinding 101
First understand how the coils are operated. Lots of excellent help on PinWiki for this era of machines. I suggest having a good read of that FIRST.
Second narrow down the faulty driver and repair/replace it as required.
Go back to basics and understand HOW the coils are operated in your machine and it will all become clear to you.
Why would you think a coil locking on makes the coil the problem? That is actually the very LAST thing I would look at in this situation.
That's the same as thinking your brake pedal is faulty because the brakes are locked on without realising the handbrake is on.

The reason why I checked the coil is because those with far more experience than I have suggested verifying that the coil was not shorted and also checking the diode to insure it was ok. Hope that clears that up

#9 3 months ago

Appreciate all those who were really helpful in their responses. Thank you. I’ll have to dig into the SDB a bit further. Thing that is confusing there is that I shot a video of the startup sequence to Dave at Alltek (very helpful) and he advised that it appeared to look correct. That is the solenoid status leds. Just a bit confused as if there was a problem other that board, I was under the notion that it was pretty intelligent to show that there was an issue

I fully get the idea of a driver transistor and how it works. Further understand that if it is shorted it will no longer “switch” but send current that will result in the coil be locked on. Again just a bit confusing when I have the manufacturer telling me it looks good. I’ll do some more digging and get to the bottom of this.

Again fellas, thank you for your thoughtful and helpful responses. I am grateful

#10 3 months ago
Quoted from GPS:

those with far more experience than I have suggested verifying that the coil was not shorted

FYI...if the coil was shorted, then it would not lock on. Instead, if it was shorted you would fail a part upstream like a fuse or transistor.

#11 3 months ago
Quoted from JethroP:

FYI...if the coil was shorted, then it would not lock on. Instead, if it was shorted you would fail a part upstream like a fuse or transistor.

Absolutely makes sense. Thank you JethroP !! I am going to check and see if the coil is somehow shorted to ground. Barring that, it must be an issue with a driver transistor on the SDB

Thank you again!

#12 3 months ago
Quoted from GPS:

I am going to check and see if the coil is somehow shorted to ground. Barring that, it must be an issue with a driver transistor on the SDB

If the transistor has failed it’s (likely) providing your path to ground. Pinwiki has a good test procedure for the transistor.

#13 3 months ago
Quoted from GPS:

I have checked the coil out if the circuit and it is good showing about 5 ohms.

That's about half what it should be. If you don't have a manual, you can download one at the link below.

https://www.ipdb.org/

Knocker coil is a 26-1200, which is about 10.8 ohms.

https://flippers.com/coil-resistance.html

Get the right coil before you do anything else. Likely another problem elsewhere, but start with the right coil (or double check part number/ reading on existing coil).

#14 3 months ago

Thank you fellas. I am sending the board back to Dave at Alltek to eliminate that from the equation. I will also verify the coil resistance again and get a new one if needed. I remain grateful to all. Thank you

#15 3 months ago

Can we be clear here - WHICH board are you sending back? The solenoid driver/power regulator board OR the MPU?

The problem is most likely a shorted driver transistor/MOSFET on the solenoid driver board.

#16 3 months ago

Thank you again phishrace !! Rechecked the coil and it is indeed the correct one according to the manual and it is showing a resistance of 10.6 ohms. So I think we’re good there. Must have fricked up the reading before. My apologies.

I also checked to see if the coil was shorted to ground somehow and it is not.

I’ll wait to see what Alltek has to say. Hopefully they find a mosfet that is bad and that will put this small issue to bed.

Thank you all!

G

#17 3 months ago
Quoted from GPS:

Thank you again phishrace !! Rechecked the coil and it is indeed the correct one according to the manual and it is showing a resistance of 10.6 ohms. So I think we’re good there. Must have fricked up the reading before. My apologies.
I also checked to see if the coil was shorted to ground somehow and it is not.
I’ll wait to see what Alltek has to say. Hopefully they find a mosfet that is bad and that will put this small issue to bed.
Thank you all!
G

Please make sure to replace the diode on the coil, watching the polarity.

#18 3 months ago

Hi Fellas

Ok think I MAY have found the issue and was hoping j could get some confirmation. Please see the attached picture.

If my suspicions are correct, I have the knocker wire (black with white trace) in space 4 of J2 on the SDB. Think this should be in soace 5. Can anyone out there confirm please?

By the way. I did send in the original SDB and now have the replacement in the game. Soni do not think I have an SDB issue. Thank you Save Seidman at Alltek

Hoping you guys can set me straight here. If this is indeed correct what I am thinking, this is the last issue!!

Thanks guys

George

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#19 3 months ago

Shit. Now that I look at it closely it IS in the right spot. With the SDB board being exchanged by Alltek, I am at a loss. Sorry guys. Thought I may have found it. But it is in the fifth spot.

When I put my meter on the black wire with white trace and the other probe on ground I get continuity. Should not be the case unless Q3 on the SDB is activated or if it is shorted which I don’t believe it to be as this was the same issue I was having before and now with a new board.

Again guys any guidance would be appreciated sorry fir the false alarm on last post

#20 3 months ago

Just fyi, Alltek did not say what they found if anything.

#21 3 months ago

Disconnect the wires from the connector (just pull the connector out) and measure with meter continuity between coil lugs and ground. If you get ground with the machine off, you have a sneak short in the wire. It's not uncommon for this to happen. In that case unless you can find the short, best to just replace that wire in the harness.

If no short that way, make a temporary jumper setup where you're replacing the wires at both ends (pull the connectors out of their housing, make a jumper up with connector pins on one end and alligator clips on the other) and replace the wiring. Test. Also, make sure the solenoid in its bracket doesn't have screws run through it at all causing a ground. Got any other coils around to swap in? Anything from a 23-800 through 26-1500 will work for a test.

Also make sure your +43 feed wire is attached to the banded side of the diode.

#22 3 months ago

Thank you for replying slochar
I did the first test you suggested by testing for ground on both coil conductors with J2 disconnected. I DO NOT get continuity

As for the coil and wiring, the two green wires are going to the banded end of the diode (+45.6) The black with white trace to the other terminal.

There are no screws running through the coil and I did ohm out the coil and it was ok at approx ten ohms.

#23 3 months ago

Take J2 off. Put meter on J2-5 Q3 on connector, and ground. Turn game on. Does it go to ground right away? If so it's something on the board shorting out, and since it's a different board, hopefully not.

Also, the lower right connector, j4 is the inputs.... try disconnecting that as well. Maybe it's an input issue since everything else seems to be ok.

#24 3 months ago

Thanks again slochar
Ok. Put probes on J2 Q3 terminal without connector on and other probe to ground. Even without turning the machine on I got continuity. This happened with J4 off as well

#25 3 months ago

Continuity that is between J2-5 Q3 and ground. Sorry fir not making that clear

#26 3 months ago

Here is a pic of the new board in the game. Screw in upper right and lower left corner to affix board. No plastic standoffs

image (resized).jpg
#27 3 months ago

Given that I do not have any plastic mounting clips on this board, just two screws in the corners could the board be shorting against the two rails it’s mounted to??

#28 3 months ago

You can float the board to test, but yes, if you get continuity between ground and the Q3 pin, it's shorted to ground. If it still does it when you are floating the board (not attached at all, the ground through the connector will have to do) the transistor is blown and back to square 1. You can test this with it off, if it's shorted to ground the transistor is toast.

If you have NO plastic standoffs at all (even leftover nubs) you should get some, the board isn't made to contact at other points. I don't think that's necessarily the issue but you never know.

#29 3 months ago

Well here is what I got (doesn’t sound good) I held the board in the air not touching anything and then checked for continuity between ground and J2-5 (Q3) and yeppir there is continuity.

As I have said before when this issue reared it’s ugly head, the knocker would lock on instantly upon game power up. After initially finding this issue we disconnected the ground wire to the coil so that nothing would get hot.

I will email Dave Seidman at Alltek and see if my bird that I sent in had a bad Q3. There was no report with the board I got back just a different bird soni don’t know.

Perplexing…

G

#30 3 months ago

Have emailed Dave at Alltek with the hopes that he can shed some light here. Just cannot figure out how Q3 would get blown as the knocker has been disconnected and only tries to connect a couple times to see if I still have the issue. When I realize I do I immediately shut the game off so I am not stressing any component by leaving it actively locked on

#31 3 months ago

Can you define "continuity". How are you measuring it? What's your multi-meter set to? What reading are you getting?

#32 3 months ago

Compare to another Q # the same way see if the reading is the same just to confirm your meter is working as it should.

I guess those diagnostic LED's on the Alltek board are only when it is firing as it would be obvious if it was measuring the actual output?

If something in the wiring is causing it to blow I'd just replace the wiring. Add a fuse to the knocker as well if you haven't done so already. Sometimes on these games the main solenoid fuse doesn't blow as it should since it's just one unfused coil for the knocker, and the wire burns the insulation off.

Does either wire to the solenoid seem crispy at all? Stiffer than it should be, or crunchy? Kind of hard to describe how it would feel, but it's different than a normal wire for sure.

#33 3 months ago

Maybe the below will help. I followed vids guide to est the Q3 and then Q19. This is what I got

409F8CBA-311A-4BC9-A943-993DD376234D (resized).png
#34 3 months ago

To answer your question about whether the wires seem crunchy”. No not at all. I understand what your asking and further the feel of a wire and insulation that has gotten really hot. Hope that helps too.

As fir the continuity question I am using the tone option on my meter

image (resized).jpg
#35 3 months ago

Again, when the new board was put in, the knocker was disconnected and only briefly connected using test leads. When it locked on I immediately shut the game off. I did not leave it in this condition for more than a second or two at most

#36 3 months ago

Just talked to Dave at Alltek and he advised that there was nothing wrong with the previous board I sent in. Hmmmmm. Now j am really confused

#37 3 months ago

Just to recap; Connectors on J2 and J4 are disconnected. Board is floating not connected to rails by screws etc. when I place the meter on J2-5 and the other lead on the ground strap I am getting continuity when the game is off.

When I check for continuity between knocker coil terminals and ground, I do not have continuity.

Thanks for all the kind assistance thus far guys. If you think of something, please let me know. Thank you

George

#38 3 months ago
Quoted from GPS:

As fir the continuity question I am using the tone option on my meter

FYI, tone mode tells you there's some form of continuity which won't necessarily be a dead short. You need to use low resistance mode on the meter. In your case you set it to the 400 Ω scale. Put the meter probes together and the reading you get (close to if not zero) is a short circuit.

But I digress..
The output of the Q3 transistor goes to J2 pin 5. *But* it also goes to SDB J3 pin 4 and you have a wire there which shouldn't be there. You also have a wire missing from SDB J3 pin 3 - this wire is supposed to be white and comes from the rectifier board J3 pin 18 which is ground.. Looks like you have that white (smokey brown in your case) wire in the wrong position of the SDB J3 connector.

#39 3 months ago

Hello Quench. Thank you very much for the assist. I will look here in a little bit and confirm. Let me get the wires correct first on the SDB and then go back and revisit the continuity situation as the fricked up wires could be causing all this. Hang tight and I’ll be back with you soon. Thank you again!!

#40 3 months ago

The driver transistor on the NEW board will be destroyed in a microsecond. You will not have a chance to turn the machine off and it doesn't matter that you only had it on for a second.

Semiconductors will be damaged BEFORE a fuse has a chance to react. If your coil has the diode around the wrong way for example BANG - the transistor will short out at switch on in less than the blink of an eye.

These things need to be confirmed BEFORE turning on a new board.

Possibly your new board is now also damaged.

#41 3 months ago

Three cheers for Quench !!!

That was it. Damn, something so simple. I am sure that I messed that up as I re-pinned all the molex connectors. Thought I paid pretty close attention. Don’t know if that was working before I got the game but bottom line is it is now. Thank you Quench and all who helped in this, at times, weird problem. Thank you all!!

George

#42 3 months ago
Quoted from GPS:

That was it.

Great to hear you've got it resolved. That left outlane's a doozy, only game I feel like putting a rubber band there to block it

#43 3 months ago

Thank you Quench. Without your direction I would still be hunting around. Thank you!!

#44 3 months ago
Quoted from pins4u:

The driver transistor on the NEW board will be destroyed in a microsecond. You will not have a chance to turn the machine off and it doesn't matter that you only had it on for a second.

Semiconductors will be damaged BEFORE a fuse has a chance to react. If your coil has the diode around the wrong way for example BANG - the transistor will short out at switch on in less than the blink of an eye.

Possibly your new board is now also damaged.

just to add. the original board had no issue. the new SDB had no issue. it was just a mispinned wire.

the OP asked the right questions, and followed leads. nice work, tricky one to diagnose.

#45 3 months ago
Quoted from youdontknowme:

just to add. the original board had no issue. the new SDB had no issue. it was just a mispinned wire.
the OP asked the right questions, and followed leads. nice work, tricky one to diagnose.

Sure, I made the (incorrect) assumption that the machine WAS WORKING and then developed this fault with a locked on coil.

Under these conditions, turning the machine on with the locked coil still connected would likely toast a replacement board in milliseconds.

That was my warning - look for the reason the coil locked on FIRST and I didn't read that this machine had NEVER worked correctly in the first place.

#46 3 months ago
Quoted from youdontknowme:

just to add. the original board had no issue. the new SDB had no issue. it was just a mispinned wire.
the OP asked the right questions, and followed leads. nice work, tricky one to diagnose.

Thank you for the kind words. I am grateful. As I said before, I was very careful when I was re-pinning so it could have very well be my mistake or it could have been there all along and I just duplicated what was there even though it was incorrect. Good thing is that issue is no longer an issue and the game is very close to being perfect. Still a couple things to dial in as usual but very close. There is NO WAY I could have fixed that issue without the great guidance here on this thread> Thank you fellas!!

G

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