(Topic ID: 119355)

Gottlieb Hot A-4893 Pop Bumper Coil Question (or How Much is Too Much?)


By MikeO

4 years ago



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    #1 4 years ago

    So I purchased several of the PBR hot A-4893 pop bumper coils to enhance the pop bumper performance in my Slick Chick. I'd like to get a Slick and/or Chick advance off the pop bumpers to the upper center advance target once in a while as I expect this was how the game played when new. The way my game was performing this was a once in 15-20 game event.

    I installed three of the hot coils last night - the top three - L & I & C. Boy are they zippy now. They are hotter than new DC operating pop bumpers. It's great if you want overkill but even this is not how these were intended to perform.

    I measured resistance and the original wavered between 2.0-2.1 ohms. The new one only pulls 0.7 ohms. This strikes me as too drastic a change. Before I purchased the hot coils I considered taking the time to remove some of the windings off a few original coils. With what I have now I need to do something different.

    So what is the math in all of this? If the 2.0 ohms is getting me 75% of the performance I want but the 0.7 ohms is getting me 150% of the performance I want, does that mean I interpolate the ohms reading I want out of the coil, as a target resistance reading, to get closer to the performance I want?

    By the way, the coils appear to have similar weight although the hot coil has notably heavier wire for the winding over the original coil.

    At the very least I have found a way to bring the performance of the game into where I think it should be. I just need to play with the windings a bit.

    Also, I suspect these hot coils may be just what I need on my Outer Space where the pop bumper action is anemic at best while the rest of the game performs well. We'll see when I get them installed there.

    #2 4 years ago

    The only other solution I can think of is to use an orange dot flipper coil and just use the high powered side of the coil. The A-4893 A appears to have about the same amount of power as the yellow dot A-5141 does. I would guess the orange dot flipper coil would have power somewhere between the regular 4893 coil and the high powered version. I think the frame size is the same.

    I'm sure the weight is about the same. Heavier wire, less turns, less resistance but about the same weight.

    Have you tried the regular coils with high tap?

    #3 4 years ago

    Rather than different coils, have you tried using a new regular coil with new sleeve, new plunger, new fiber yoke, new metal yoke, and new ring (if there's any play in the rods on the current ring)? And then also make sure the EOS switch stack is clean and tight (if it's the style that passes the signal via the screws), with good contacts, and set to open at nearly full stroke. Want the coil to get a good clean signal to fire, and full stroke.

    Those 60's pop bumper plungers+yokes take a lot of abuse, and wear down. When that happens, the extra slop in the action takes away from what the ring can impart on the ball, making the pop action weaker. When the plunger+yoke are new and tight and there's no play in the stack up with the ring, the regular coils can provide more kick. Might be enough to accomplish what you want.

    #4 4 years ago
    Quoted from DirtFlipper:

    Rather than different coils, have you tried using a new regular coil with new sleeve, new plunger, new fiber yoke, new metal yoke, and new ring (if there's any play in the rods on the current ring)? And then also make sure the EOS switch stack is clean and tight (if it's the style that passes the signal via the screws), with good contacts, and set to open at nearly full stroke. Want the coil to get a good clean signal to fire, and full stroke.
    Those 60's pop bumper plungers+yokes take a lot of abuse, and wear down. When that happens, the extra slop in the action takes away from what the ring can impart on the ball, making the pop action weaker. When the plunger+yoke are new and tight and there's no play in the stack up with the ring, the regular coils can provide more kick. Might be enough to accomplish what you want.

    I didn't want to be the one to ask that question, because I figured Mike is knowledgeable enough to know rebuilding the bumpers would help a lot, and I assumed he had already done that.

    I just rebuild them as a matter of course. The parts are cheap enough that it's well worth it to do.

    #5 4 years ago
    Quoted from DirtFlipper:

    Rather than different coils, have you tried using a new regular coil with new sleeve, new plunger, new fiber yoke, new metal yoke, and new ring (if there's any play in the rods on the current ring)?

    Already done, except for new rod/rings. They were in excellent condition to begin with.

    No high tap for me. The rest of the game plays just right. Flippers are rebuilt and strong and slings pop like they are supposed to.

    My experience has been that the pop bumper performance is harder to recover than flippers and slingshots. Either that's just the case or I'm missing something in refreshing the pop bumper circuit. I've also replaced the switch on the pop bumper relays that actuates the ring/rod with new, thinking that might be the weak link, with no improvement.

    Putting the hot coils was a huge improvement (over improvement) in performance which really brings me back to my original question - how many windings should I remove from an original coil to get a balanced performance? Or to what resistance value? It may be just trial and error until I find the sweet spot.

    I believe Clay was doing this long ago. I remember a Cross Town he had at Expo about 10 years ago where he indicated he had removed windings from the pop bumper coils to get their performance in line with the rest of the game.

    #6 4 years ago
    Quoted from MikeO:

    Already done, except for new rod/rings. They were in excellent condition to begin with.
    No high tap for me. The rest of the game plays just right. Flippers are rebuilt and strong and slings pop like they are supposed to.
    My experience has been that the pop bumper performance is harder to recover than flippers and slingshots. Either that's just the case or I'm missing something in refreshing the pop bumper circuit. I've also replaced the switch on the pop bumper relays that actuates the ring/rod with new, thinking that might be the weak link, with no improvement.
    Putting the hot coils was a huge improvement (over improvement) in performance which really brings me back to my original question - how many windings should I remove from an original coil to get a balanced performance? Or to what resistance value? It may be just trial and error until I find the sweet spot.
    I believe Clay was doing this long ago. I remember a Cross Town he had at Expo about 10 years ago where he indicated he had removed windings from the pop bumper coils to get their performance in line with the rest of the game.

    Well, since the standard coil is showing about 2 ohms of resistance and the hot coil .7 (didn't even think that possible, below 1 ohm is usually a dead short and a fuse blower) I'd guess you want to get around 1.3-1.5 ohms. Maybe take three turns off, but that's not scientific at all. If it's not enough you could go further, but the risk is going too far and then the coil is no good.

    #7 4 years ago

    I'm sure there is a big arse formula way to figure it out, but interpolating is a good "guess". The function won't be linear, but I think experimentation will get you there faster.

    Gottlieb EM pops are already the best ever, but I bet that Slick Chick will play really fun and fast with a bit of a "tune up".

    --
    Chris Hibler - CARGPB#31
    http://www.Team-EM.com
    http://webpages.charter.net/chibler/Pinball/index.hm
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    #8 4 years ago

    I have done this before and agree that three layers of wire is about right.

    #9 4 years ago
    Quoted from ChrisHibler:

    I'm sure there is a big arse formula way to figure it out, but interpolating is a good "guess". The function won't be linear, but I think experimentation will get you there faster.
    Gottlieb EM pops are already the best ever, but I bet that Slick Chick will play really fun and fast with a bit of a "tune up".

    --
    Chris Hibler - CARGPB#31
    http://www.Team-EM.com
    http://webpages.charter.net/chibler/Pinball/index.hm
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    Eh, Gottlieb pops can't compare to the DC pops Williams used in the 70s. It's like comparing a Model T to a Corvette.

    Even Bally's 50v pop bumpers of the 60s are way stronger and faster than a Gottlieb bumper. Now, if we're going to compare apples to apples Gottlieb bumpers are fine, but I wouldn't agree at all that they are the best EM bumpers ever made.

    #10 4 years ago

    coil properties calculator...

    http://www.daycounter.com/Calculators/Coil-Physical-Properties-Calculator.phtml

    i haven't done the "unwind the coil" trick, but from everything i've read, 3 layers is what seems to be the magic number...

    #11 4 years ago

    I pulled 2.5 layers off of two of them last night and put them in the center and an upper pop bumper position and played the game along with one of the PBR hot coils in the other upper position. The modified coils were pulling 1.6 ohms. They played better but I could already tell I would be happy to go with removing three full wraps. So the 2.5 removed wraps will go to the two bottom pop bumpers and the center and two upper pops will get three full wraps removed.

    #12 4 years ago
    Quoted from MikeO:

    I pulled 2.5 layers off if two of them last night and put them in the center and an upper pop bumper position and played the game along with one of the PBR hot coils in the other upper position. The modified could were pulling 1.6 ohms. They played better but I could already tell I would be happy to go with removing three full wraps. So the 2.5 removed wraps will go to the two bottom pop bumpers and the center and two upper pops will get three full wraps removed.

    Good deal. Sometimes my lucky guesses work out ok

    #13 4 years ago

    How many turns is that? I've always heard to unwind about 40 turns if you want a snappier pop bumper or a louder knocker. Not that I would do such a thing...!

    #14 4 years ago
    Quoted from jrpinball:

    How many turns is that? I've always heard to unwind about 40 turns if you want a snappier pop bumper or a louder knocker. Not that I would do such a thing...!

    number of turns would vary depending on the wire gauge. I think 40 is way low, likely more like 140 to equal three layers of the coil bobbin....!

    #15 4 years ago

    I didn't count the turns or mic the wire gauge. I can do a quick count on the two coils I have left to modify tonight. I'm going to guess 120-150.

    The problem is it's easy to spool off the wire. I don't know why I didn't try this before instead of buying 6 hot coils at $7.50 each.

    #16 4 years ago

    Now I am totally confused-turns? layers?

    #17 4 years ago

    turns = how many times the wire is wound around the bobbin...

    layers = a "layer" of "turns" on the bobbin...

    #18 4 years ago
    Quoted from MikeO:

    I didn't count the turns or mic the wire gauge. I can do a quick count on the two coils I have left to modify tonight. I'm going to guess 120-150.
    The problem is it's easy to spool off the wire. I don't know why I didn't try this before instead of buying 6 hot coils at $7.50 each.

    Well, I didn't want to sound like a cheapskate, but I had that very thought when I read you had bought those 'hot' ones. Not that hard to do, just be careful with the wrapper and you can reuse that with hardly any evidence that it has been tampered with!

    #19 4 years ago
    Quoted from EMsInKC:

    Eh, Gottlieb pops can't compare to the DC pops Williams used in the 70s. It's like comparing a Model T to a Corvette.
    Even Bally's 50v pop bumpers of the 60s are way stronger and faster than a Gottlieb bumper. Now, if we're going to compare apples to apples Gottlieb bumpers are fine, but I wouldn't agree at all that they are the best EM bumpers ever made.

    Ahem...the beauty of pinball...to each his own.
    I love the power and the solid feel of Gottlieb pops.
    Bally and WMS just don't feel the same.
    WMS from the late 60's are really lame.
    Again, to each his own.

    I recall a lot of carping about Stern flippers when they started releasing games. Folks said they just didn't feel like WPC flippers. True, but I've really grown accustomed to them, and now love them on my IMVE.

    Whatever you like or prefer...play a game tonight...
    --
    Chris Hibler - CARGPB #31
    http://www.Team-EM.com
    http://webpages.charter.net/chibler/Pinball/index.htm
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    #20 4 years ago
    Quoted from stashyboy:

    Well, I didn't want to sound like a cheapskate, but I had that very thought when I read you had bought those 'hot' ones. Not that hard to do, just be careful with the wrapper and you can reuse that with hardly any evidence that it has been tampered with!

    Grrr stashyboy I just hope I never buy a machine where that has happened and is not appropriately labelled. In any case I just find when you do anything to a machine it is difficult to remember down the track what you did so it is great to record or in this case label.

    #21 4 years ago
    Quoted from wayner:

    Now I am totally confused-turns? layers?

    Yes, layers, like layers of cord or thread on a bobbin. It's really a thing of beauty under the wrapper, all lined up nice and neat. The difficult thing to do was remove an odd number of layers as that put the wire at the opposite end of the bobbin from where the solder tab was. The OCD in me had to hesitate seeing the wire pulled diagonally to the opposite end across those nice neat rows.

    Quoted from wayner:

    Grrr stashyboy I just hope I never buy a machine where that has happened and is not appropriately labelled. In any case I just find when you do anything to a machine it is difficult to remember down the track what you did so it is great to record or in this case label.

    I'm already recording the ohms reading on the replaced wrappers for future reference. At least it will cause someone to consider what it means when this ends up in someone else's hands after I'm gone. But it will play well.

    #22 4 years ago
    Quoted from stashyboy:

    Well, I didn't want to sound like a cheapskate, but I had that very thought when I read you had bought those 'hot' ones. Not that hard to do, just be careful with the wrapper and you can reuse that with hardly any evidence that it has been tampered with!

    I need two in my Outer Space where the pops are truly anemic, so no loss. Even then, they may be overkill for as strong as they were in Slick Chick. It will be spring before I get that game set back up. I'll report back how they do at that time.

    #23 4 years ago
    Quoted from ChrisHibler:

    Ahem...the beauty of pinball...to each his own.
    I love the power and the solid feel of Gottlieb pops.
    Bally and WMS just don't feel the same.
    WMS from the late 60's are really lame.
    Again, to each his own.
    I recall a lot of carping about Stern flippers when they started releasing games. Folks said they just didn't feel like WPC flippers. True, but I've really grown accustomed to them, and now love them on my IMVE.
    Whatever you like or prefer...play a game tonight...
    --
    Chris Hibler - CARGPB #31
    http://www.Team-EM.com
    http://webpages.charter.net/chibler/Pinball/index.htm
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    I think sometimes we feel what we expect to feel, if you understand what I'm saying.

    That's the whole thing, Chris. They're basically not as powerful as the 70s Williams bumpers, or the 60s 50v Bally bumpers. Heck on some of their 60s games Bally used metal skirts-I have a game with them. A very solid feeling, strong and powerful bumpers.

    I'm fully aware that I often go against the grain of the Gottlieb love affair on here. I think they made great games, and probably on the whole better games than the others. That doesn't mean that the others didn't have games that were superior to Gottlieb, or that they didn't have ideas and features that were superior also.

    #24 4 years ago

    I think there are a couple of competing issues here:
    The lower the number of turns, the lower the resistance
    The lower the resistance, the more current.
    The more current the higher the force.

    But....if you wrap the wire around 3 times, obviously this won't hold up, so there are some parameters you likely need to operate within.

    Then, you probably need to consider power dissipation and the ability of the hot coil to not self destruct.
    As you lower the turns, you are passing more current/power.
    Generally, the more current you pass, the larger diameter you want the wire to be. BUT since you just unwrapped the wire, you are stuck with what you have.

    So....you may end up with crunchy, burned up coils, depending on how far you go. I don't do this, but I have worked on games and had to replace crunchy, burned up, homemade hot coils.

    YMMV.

    #25 4 years ago
    Quoted from newmantjn:

    I think there are a couple of competing issues here:
    The lower the number of turns, the lower the resistance
    The lower the resistance, the more current.
    The more current the higher the force.
    But....if you wrap the wire around 3 times, obviously this won't hold up, so there are some parameters you likely need to operate within.
    Then, you probably need to consider power dissipation and the ability of the hot coil to not self destruct.
    As you lower the turns, you are passing more current/power.
    Generally, the more current you pass, the larger diameter you want the wire to be. BUT since you just unwrapped the wire, you are stuck with what you have.
    So....you may end up with crunchy, burned up coils, depending on how far you go. I don't do this, but I have worked on games and had to replace crunchy, burned up, homemade hot coils.
    YMMV.

    That's a good point about longevity. That concern has been raised about high-tapping games that are using full house current. Steve Young has told me high-tapping will not harm your coils/mechs. My take would be there might be some minimal extra wear there, but we are talking about home use, with limited plays. Same could be said about the 'hot' coils. Agreed, don't go too far with the concept and you will stay within an acceptable amount of extra heat. Since Steve sells them, I would think he's had feedback that would support their use without long term issues.

    #26 4 years ago
    Quoted from stashyboy:

    Since Steve sells them, I would think he's had feedback that would support their use without long term issues.

    Quoted from MikeO:

    By the way, the coils appear to have similar weight although the hot coil has notably heavier wire for the winding over the original coil.

    But, but, but....Steve redesigned the hot coils with the heavier wire, I'm assuming to compensate for the additional current. So comparing Steve's hot coil with the heavier wire to a homebrew version is not apples and apples. Regardless, if you were just going to chuck them in the trash anyway, may as well give it a go. If they burn up, they burn up.

    #27 4 years ago

    It's not like they're continuous duty coils anyway. The additional heat is probably pretty negligible.

    #28 4 years ago

    with a .7 ohm coil I think steve would have increased the wire gauge.
    when I unwrap a coil I try not to go below 1.30 ohms but with a high gauge wire I am sure less than 1 would be fine but IMO I think they would be to strong. I might add one of those to a future order just to check it out.

    #29 4 years ago
    Quoted from boilerman:

    with a .7 ohm coil I think steve would have increased the wire gauge.
    when I unwrap a coil I try not to go below 1.30 ohms but with a high gauge wire I am sure less than 1 would be fine but IMO I think they would be to strong. I might add one of those to a future order just to check it out.

    It was way strong. Hotter than the pop bumpers in a new Stern game.

    I was truly concerned I would break something on the playfield.

    What it tells me is that Steve sized it for overly weak woodrails and other applications where the pop performance has deteriorated severely.

    #30 4 years ago

    Years ago I unwound 3 layers off of my Buckaroo pops and I love it.
    Ted

    #31 4 years ago

    i read that you can take off a max of 4 layers , any more than that could be a short , so dont get greedy. i tried 3 layer removal and was happy with the results. on a target alpha the top pop bumper was strong enough to knock down drop targets.

    #32 4 years ago

    So I ended up taking off three full wraps on the center and upper two pop bumper and 2.5 full wraps off the lower two pop bumpers.

    The game plays much zippier and my scores are showing it. I'm regularly hitting the replay thresholds and earning 3 and 4 lit roll overs (completing the SLICK CHICK sequence) where the norm used to be 2, maybe three lit roll overs. I would say that 3 full wraps, for as strong as my game was originally playing, was probably too much. After more play time, and a few replay score threshold adjustments, I may be right where where I want to be.

    #33 4 years ago

    I took 3 layers off the pops in my Heat Wave and Quick Draw. In both cases the results were great - particularly on Quick Draw.

    In general I think that many Gottlieb large drop target bank games play "slow" (ball goes up - hits or misses drop target - ball comes down), but with the snappier pops there is much faster ball movement including some from the center pop the keep you on your toes with the flippers.

    On my Sing Along I did nothing to the pops beyond my standard rebuild. I was concerned that it would radically change the flow of the game what with the importance of the side roll-overs and the row of kick-out holes just below the pops. You can notice that the pops are not as powerful as on my other games, but the overall play nice and the four pops are fun.

    On a side note I'm kind of with EMsInKC; I think that overall, Gottlieb made more really good games than anyone else in 60's to mid-70's, but that Williams made some that stand up to (or surpass) the best of Gottlieb. Two of the favorite games I have ever owned are Heat Wave and Teacher's Pet. And while my Nag's is not the worlds greatest player (a lot of luck involved) it is still an awesome engineering and design feat that is probably the most popular game when I have parties.

    1 month later
    #34 4 years ago

    Agreed... Gottlieb was more consistently great with their string of hits, but brand loyalty often gets the better of many of us. Gottlieb wedgeheads, in particular, seem to get almost universal love but frankly quite a number of them are just "OK". Don't be fooled by that trademark shape... it's only one aspect of the elusive magic pinball formula.

    I've found a number of Williams and Bally games (and multiplayer Gottliebs) which are every bit as fun to play as some of the most cherished wedgeheads. I restored a Doozie (sans hi-tap) which plays incredibly fast and furious. Great action in that cluster of 5 pops!

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