(Topic ID: 293848)

Gottlieb Big Shot Repair

By Flip-it-good

1 year ago

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  • 180 posts
  • 14 Pinsiders participating
  • Latest reply 3 months ago by Flip-it-good
  • Topic is favorited by 3 Pinsiders


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There are 180 posts in this topic. You are on page 4 of 4.
#151 5 months ago

Nice idea with the slow motion cell phone! We watched the video and although the pawl does get very close to the end of each tooth I adjusted it where the pawl stop is further into the tooth. No skips and the end of ball bonus still stiffs you on 2-4 thousand each time. It occurs less if you just hit a few targets and have a bonus under 5k. Could there be something before the end of ball unit that is not doing something? Like, what tells the end of ball bonus unit what to do?

1 week later
#152 4 months ago

Can someone please do me a favor and let me know where these two wires go.
Thanks Fernando

20220323_110047_HDR[1] (resized).jpg
#153 4 months ago

The black wire from ‘U’ goes into the harness and goes to the Knocker (or perhaps the chime unit).

I don’t have a BL-WH but I do have a WH-BL in that position on ‘W’, according to the schematic it also goes to the Knocker.

C3DBC17C-DF19-4918-B156-248F91F70E91 (resized).jpeg

Caveat: I’m in the middle of repairing this non-working game.

#154 4 months ago
Quoted from AndrewP:

The black wire from ‘U’ goes into the harness and goes to the Knocker (or perhaps the chime unit).
I don’t have a BL-WH but I do have a WH-BL in that position on ‘W’, according to the schematic it also goes to the Knocker.
[quoted image]
Caveat: I’m in the middle of repairing this non-working game.

Thanks Andrew it makes sense since the knocker and chime unit is missing in my game.

#155 4 months ago
Quoted from Flip-it-good:

Nice idea with the slow motion cell phone! We watched the video and although the pawl does get very close to the end of each tooth I adjusted it where the pawl stop is further into the tooth. No skips and the end of ball bonus still stiffs you on 2-4 thousand each time. It occurs less if you just hit a few targets and have a bonus under 5k. Could there be something before the end of ball unit that is not doing something? Like, what tells the end of ball bonus unit what to do?

how confused would you like to be?

typically, a bonus unit steps up to accumulate a bonus, then when the ball drains it steps down and points are added for each step.

your bonus unit doesn't do that. Instead, it's a 15 step unit that is looking at each drop target one at a time to see if it's down. If it is, then points are added.

so first check is make sure all the "pool ball" lights work. If they don't, could be the drop target switch is not working and you won't score a bonus for that pool ball.

assuming all your pool balls light, then look at the schem around 3B:

1] when a ball falls in the ball return hole (outhole). The C relay powers and the C switch with the YEL and GR+WH wire closes.

2] if drop target #1 is down, J powers

3] J powering causes I to power

4] the circuits around schem 5G cause the L relay to power and increment the 1000's reel. How many times it increments depends on the LB and HB switches letting more pulses thru, but it should increment at least once via 1D

5] score motor 1B switch closes and steps up the bonus unit. Note this happens whether scores were added or not.

that sequence repeats until the bonus unit has stepped all the way around back to home, at which time more stuff is triggered and the ball is either kicked to the shooter or the game ends so the whole bonus sequence doesn't start again.

you'd have to work thru all the circuits and the score motor switch timing to understand exactly what is going on, but if it's mostly working, what you want to know is:

1] is it not scoring a particular pool ball?

I usually knock down half the drop targets and collect the bonus. If it short pays, I reset and knock down less until you find one(s) that don't work. If first half works, reset and try second half.

2] if it is scoring all pool balls, but not reliably, I'd knock down all the targets and watch I and J relays to see if they aren't powering consistently.

you can also shotgun it and check:

- motor 1A
- motor 1D
- I relay switch

above 3 in L relay coil circuit

- C, O and I relay switches in J relay coil circuit at schem 3C

#156 4 months ago

Thank you so much, I will check all of these. I just cleaned all of the switches for the pool ball lights. I didn't realize that the light being on or off told some other system whether to score or not. I see three types of switches for the target Banks, one for the ball lights, one to score the 500 points when the target drops and one leaf switch that seems to be attached to the whole Target Bank in the center. I did check each drop target individually and let the ball drain with the exception of an intermittent one, the 15 ball, all seem to score okay at the end of ball. It seems to only rob you of points when there's multiple targets down. And when you get to the fifth ball and all targets are worth 3,000 each, missing two or three is significant in your scoring at the end of the game! I'm not a designer but this seems like one of the most complicated end of all bonus systems. That bonus score unit takes a serious beating even if there's no score at the end of the ball.

1 week later
#157 4 months ago

Tried cleaning everything again. Rivets are hitting perfectly, no tooth skipping on the gear. Found a nice dead end.

#158 4 months ago

can you make your video of the bonus unit available?

the bonus unit itself should step up at a regular cadence, and the score reels are kinda independent of the bonus unit stepping.

you'll want to determine if the bonus unit stepping is the problem or the score reels incrementing is the problem.

one place you could get in trouble is if the switch dogs on the score motor are in the wrong slots. See the chart around A14 on the schem. A dog is the thing with S/L slots riding the cam edge. If someone took the switch stack off, the dogs sometimes fall off and putting them back in the wrong slot would affect switch timing, which could cause the wrong number of pulses to get to coils.

when all else fails, I disconnect the score motor and turn the cams by hand and so it's easy to watch what is going on. Some games have a "service plug" to make disconnecting easy, other you have to unsolder a wire and use a jumper to reconnect when you want the motor to run by itself (like when setting up the conditions before you want to turn the cams by hand).

the one gotcha is don't turn the cams by hand when the 120V coils will fire. You can't turn the cams fast enough and the fuses will likely blow. If you need to turn the cams when those coils fire, remove the fuses and reset the banks manually at the appropriate time. Also, don't leave solenoids powered for a long time or some smoke will leak out of the coils. A few seconds is fine.

#159 4 months ago

Thank you Baldtwit for some great information...Here's the link to my YT channel showing exactly what's going on at end of ball...

#160 4 months ago

ok, so when working the bonus sequence is add 1000 (and ring the chime), then step the bonus unit once.

the bonus unit double stepped 3 times and you got shorted 3000, so the problem is the bonus unit double stepping.

first thing is to repeat the experiment and point your camera at the J relay. It should pretty much stay powered if all 15 balls are lit. If you can get a video angle with the J relay and the bonus ratchet visible at the same time, that'd let you see if J is dropping out.

the most common issue is J is not powering reliably do to wiper <-> rivet connection issues on the bonus unit.

if J is stable, then it gets messy and the below will be confusing to most sober people.

short answer is try and gap score motor 3C so it opens as late as possible (near the top of the cam lobe) and score motor 1A so it only closes near the top of the cam lobe.

tmi below

if I'm reading the schem correctly (start worrying), the circuit will rapidly step the bonus unit 5 times via score motor switch (SCM) 1A in a 120 cycle (rotation of the score motor).

if after each step the J relay powers to indicate a lit ball, the remaining 1A pulses in the cycle are ignored so the bonus unit stops stepping.

near the end of the cycle, motor 2B closes and causes the I relay to power.

I relay keeps itself powered until SCM 3C opens, which is near the end of the NEXT cycle. Before 3C opens, the score reel and chime do their thing and the I relay switch is preventing 1A from stepping the bonus unit.

the ugly bit is when the scoring is done, the bonus steps via SCM 1B at the time of the 4th 1A pulse and you have only a few degrees of cam rotation before 3C opens, the I relay drops out and the 5th 1A pulse could step the bonus unit again.

there's a bit of a race condition with things changing state close to the same time.

the best way to ensure a predictable race winner is gap SCM 3C so it opens as late as possible. You want there to be max time for the bonus unit wipers to rotate and J relay to do it's thing before the 1A switch closes for the 5th time in the cycle.

having a large 1A gap will keep the pulse width narrow and therefor delay powering the bonus unit step up coil a bit.

if you repeat videoing the bonus unit ratchet a few times and the double step moves around, that would suggest a timing issue rather than a problem with the bonus unit wipers. The timing is so tight you sometimes lose the race and get a bonus step because J hasn't stabilized yet.

#161 4 months ago

Holy cow! I read that whole bottom part and just started to laugh out loud!! I'm sure if I take it one sentence at a time I'll eventually figure it out lol! I will start with re-gapping 3C and 1A with the max timing you suggested and will post another video with all 15 balls energized and a view of relay J. Thanks for taking the time to lay it all out!

#162 4 months ago

So if I understand correctly, 3C the contacts are spread as far as they can go and close at the last possible moment when the highest point of the dial comes by and the same with 1A the bottom set of switches. I'm assuming you mean that 1A should also close at the last possible moment when the tooth comes by. I will be posting a video in the next few minutes....

#164 4 months ago

I got rid of big shot because i could not get this dialed in. My hot shot works 98% of the time. Ive played others with problems. The change that resulted in the best improvement, for me, was to adjust the length of the plunger travel on the bonus stepper. I feel it's a bad design.

#165 4 months ago

I tend to agree, the amount of work the bonus unit does is insane!

#166 4 months ago

even when slowing down the video it's hard to tell when the score motor switch state is unknown and the bonus step up coil can't be seen at the same time as the I and J relays.

quick check is look at the I relay and make sure the make-break switch with the green-red wire on the moving blade is working well. Also check the J relay switch with the slate+red and green+red wires is opening well.

a second quick check is just hold the J relay closed when dumping the ball in the outhole. Do you get all bonus points then?

what you really want to know is when the bonus unit is stepping in relation to the state of the J and I relays, and the easiest way to see what is going on is to disconnect the score motor.

take a look at the score motor ... the power wire on the motor is black and the other is brown+red. The schem doesn't show one, but sometimes brown+red will go to a single pin plug/socket. If it doesn't, you'll need to unsolder the wire from the motor, then reconnect it with a jumper that you can remove.

set up your game to the state you had when you said "end of ball", and before dumping the ball in the outhole remove the jumper so the motor won't power.

put the ball in the outhole and then turn the motor cams counterclockwise with your hand. The interesting times is when the 1A, 1B, 1C, 2B and 3C switch stacks are changing state.

1] when the ball went in the outhole, C and J should power and stay powered

now you turn the cams slowly:

2] nothing should happen when the 1A and 1B stacks lift.

3] when you've gone almost 120 degrees, the 2B stack changes state. At that time, I should power and J should stay powered.

4] keep turning a bit and the 1C stack falls in the cam notch. J should unpower.

5] keep turning and the scoring/chime happens, and the next time 1A and 1B lift at the same time, the bonus unit step up coil should power. I should be still powered at that time.

the key question is whether the bonus unit is stepping BEFORE the score has been added to the reels ... it shouldn't when you are supposed to get a bonus score.

fwiw, your switch dog in the 2C stack appears to be in the wrong slot per the schematic chart, but the schem chart could be wrong. 2C shouldn't cause your issue anyway. I'll pull a big shot out of the pacific pinball museum's piles and see how that one is set up next monday.

#167 4 months ago

Wow, another fantastic bank of information. I will run these checks and follow up....thank you!

#168 4 months ago

Blades look good at I and J relays, opening and closing properly and clean. If I hold the J relay in when the ball goes to the out hole I get every single thousand!....and even more if I keep holding it in. It's also a perfect EOB bonus with the double and triple scores of ball 4 and 5.
What does that tell me?

#169 4 months ago

holding the J relay armature down and having it work just suggests the issue is with powering/holding the J relay powered ... tho other stuff could still be the issue.

if you aren't up for manually turning the score motor yet, then another test is to jumper around the bonus unit wipers - jumper the yellow wire on the bonus unit to any of the 15 wires coming from the drop target switches - assuming all the targets are down - and see what happens.

if you have flaky behavior in the wipers<->rivet connection or the wiper->yellow wire, the J relay may not power reliably and since the bonus scoring is happening so fast, a hiccup getting J to power enough to close the hold switch on J (MAR-WH to WH wires) would cause that bonus score to skip.

for the wipers, pull up the wiper and make sure it snaps down onto the rivets (moves easily in the tube). Verify the flex wire on the wiper is attached so you aren't relying on the wiper touching the tube it's going thru. If that's all good and the rivets are reasonably clean and undamaged, it should work ok.

#170 4 months ago

Ok, I'm going to check all of those things and then I will absolutely do the manual score motor cam turning. I will un-solder the score motor black wire and slowly turn the cam counterclockwise and follow your steps...stay tuned....

#173 4 months ago

Part 2...

#174 4 months ago

ya missed the 'set up your game to the state you had when you said "end of ball", and before dumping the ball in the outhole remove the jumper so the motor won't power.' part.

you want to connect the score motor when dropping the targets so all the scoring stuff happens, then when the score motor stops you can disconnect the score motor and stick your wedge in the outhole.

notice the notches in the top cam (C) of the score motor ... 3 of them spaced 120 degrees apart. When the score motor is stopped, stack 1 is in a notchso switch 1C is open. A score motor cycle is 120 degrees of rotation, so when turning you are watching what happens until/including stack 1 falls into the next notch.

so get the targets down and the game done with it's scoring for that, then disconnect the score motor and refer back to post 166 and the numbered list starting at [1].

the key thing is an ambiguity in the timing diagram for switch 2B. I'm assuming when you first wedge the outhole switch, the C and J relays power, but the I relay does not. You can verify by looking at the 2B switch with the YEL+BLK and BR-BLK wires. If it's open when the motor is at rest and only closes when the motor has turned about 110 degrees into a cycle, then for the entire first cycle nothing should happen until I powers at 110 degrees ... no scoring, no bonus unit stepping.

scoring and bonus unit stepping should happen on the next cycle. i.e. it takes two cycles to score a bonus for a ball the first time or when the previous ball wasn't lit. When the bonus scores and the next ball is also lit, the next one will score on the next cycle.

when balls aren't lit, the bonus unit can step multiple times in one cycle.

'course, I could have this wrong or the timing diagram is wrong, but if you do another video you want to call out when J and I power/unpower and the bonus unit steps. The scoring is easy to hear due to the chime.

#176 4 months ago

you were good up thru 2:10 into the video ... except you weren't looking at J.

at 2:31 into the video just after it scored the second time, the bonus unit stepped correctly, then almost immediately stepped again. That second step is wrong and is what is causing you to miss bonus points. I assume the second step happened when 1A closed ... the stack is just barely not visible in the video when you panned back to the motor.

guess who gets to make another video? ... or at least check something

do the whole process again and note when the J relay is powering and unpowering.

what you really want to do is:

1] manually turn the cam the first time and verify nothing happens in the first cycle (120 degree rotation) until near the end when I powers

2] turn into the second cycle past the scoring/chime and stop immediately after the bonus unit steps (coil unpowers).

there's a timing overlap at this point that may be sensitive to switch adjust, so one of the following should be true

[A] I is powered and J in not powered
[B] I is not powered and J is powered

in either case, motor 1A must be open still (1A stack not lifting on the cam tooth).

if the state is [A], turn the cams very slowly and make sure it changes to [B]. You must be in state [B] before 1A closes or you will get a second bonus unit step and lost bonus scoring.

I'd watch motor 1A and if the stack starts to move after the bonus unit steps, stop!

[X] If J is not powered, you need to find out why.

[Y] if J is powered, keep turning the cams. If the bonus unit steps when 1A closes, then you have a J relay switch that isn't working right.

since your problem is intermittent, you will likely need to manually turn the cams multiple times until [X] or [Y] happens.

the ideal thing is [X] ... you leave the score motor stopped at the position when J should be powered and examine the below circuit. Just to emphasize, I should be unpowered at this time.

bs-j relay (resized).png

I just use a voltmeter ... one probe on the wire on the BLK-WH on the J relay coil, the other poking along the highlighted path until you find where the 6VAC drops/disappears.

note the wire colors on the J relay coil are BLK-WH and MAR-WH. If you can't tell the difference, put a meter probe on the a 6V fuse (either end of either one) and poke the J relay coil lugs with the other probe when the J relay is powered. When you see 6V, that's the BLK-WH wire.

if [X] is the issue and the meter doesn't find the problem (or you don't have one), then you'll need to use a jumper wire. You could leave the score motor connected, but before closing the outhole switch jumper the C, O and I relay switches one at a time and see if that makes a difference. e.g.

jumper YEL to GR+WH on the C relay and close the outhole. If it reliably scores the bonus, that's the problem switch. If still flaky, repeat but jumper GR+WH to SL+WH on the O relay, etc.

the upper circles in the bonus unit box on the schem are all connected like the #15 path shows since all the targets are down. To eliminate the bonus unit wipers as a problem, you'd jumper YEL to BR-BLK on the bonus unit and as long as 15 target is down, you should score 15K.

if you aren't sure of the switch adjust, try and take a video of the sides of the switches on the I/J/C relays with the game power off and manually operating the armature plate. Need to see the behavior of the armature and the contacts. If you can't get to the I or J or C relay easily with the camera, do it on any relay that's easy to see. The key things are the armature lifting all the way, the overtravel of the blades after contacts touch and the switch gaps on open switches.

#178 4 months ago

The video clip seems to play fine on this end can anyone else see this?

#179 4 months ago

video ok now.

I guess I haven't been clear about what you are doing in this process.

you should be turning the score motor manually UNTIL you see a problem. No reattaching the score motor wire since the problem occurring then won't help you.

when you start, the motor 1C stack is in a notch. You turn the cams until the motor 1C stack is in the next notch. That is 1 cycle, and is a 1/3 rotation of the cams.


setup: C and J relay is powered after you put your outhole wedge it. C should stay powered the entire time.

cycle 1: nothing should happen until near the end of the cycle and the I relay powers. In all your vids, this is working right.

cycle 2: score/chime happens and the bonus unit steps one time. This is the bonus for ball 1

cycle 3: score/chime happens and the bonus unit steps one time. This is the bonus for ball 2

cycle 4-15: score/chime happens and the bonus unit steps one time. This is the bonus for ball 3-14.

cycle 16+: if you get this far without seeing the problem, then either try again or give up on this technique and it's jumper wire time.


here's what to do maybe rephrased a little.

1] set up the game and put your wedge in.

2] turn the score motor 1 cycle quickly since that works.

3] start turning into the next cycle slowly and stop turning right after the bonus unit steps.

4] you primarily care about the J relay and what is happening with score motor switch 1A (green arrow in pic below). You can turn the cams a little more, but you must stop turning before the 1A switch stack starts getting lifted by the last cam lobe (purple arrows ... there's 5 lobes in a cycle, and four have already passed under the stack, so there's one left in the cycle).

at the time 1A is going to start lifting by the last cam lobe, J must be powered. If it is, this cycle is going to be ok and you need to turn into the next cycle. Once you get the hang of it, you can turn quickly to the spot after the bonus unit steps and stack 1 is touching the cam lobe but not lifting. Keep repeating that to see if you can find a cycle where J is not powered.

if you find a J not powered cycle, now you need to figure out why J is not powered. See the highlighted schem and description in post 176.

big shot - gtb - score motor dog (resized).jpg

the red arrow is pointing at the correct L slot for the stack 2 switch dog. I think your dog is in the wrong slot. If so, you need to remove the switch stack and reposition the dog. The remaining stacks with dogs should all be in the S slot.

#180 3 months ago

Ok, thank you, will follow this and report back....very good stuff here ...

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