2 pics rather than words

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Wanted : Dead or Alive - In any condition
Gottlieb SPACE WALK
You find, you win : REWARD USD 500 !

http://www.facebook.com/kangourou.flipper?fref=ts

i really don't recommend this under any circumstance. if you have flipper buzz, there a lot of ways to address that (though technically it's not a problem, well, unless you consider OCD a problem.) So going down this Ac to Dc road really isn't a solution to this issue.

Well...yeah. You're providing a higher consistant voltage if it's fully rectified. There's only a flat line of peak voltage as opposed to it cycling between +whatever and -whatever where it's only at peak power for extremely short periods of time, and at much less inbetween.

I'm using individual bridges for the pops on my woodrail. They are certainly more powerful, maybe a bit too much. What I really need is to get them the way I would like them - something between what they were and what they are now - is maybe remove the bridges and go to slightly higher power coils.

I wanted to try going to DC on the flippers, but keep talking myself out of that one.

on lock relays, if you go to 1/2 wave dc rectified (as shown in the pinrepair.com/em documents), you *must* go to a high resistance relay coil. for example on gottlieb, a 30 volt system (unlike your 50 volt williams game), the stock resistance on the hold relay is about 30 ohms. When i got to 1/2 wave dc, that coil increases to 200 ohms! if you don't do that the relay coil will burn up right quick. also going to the 200 ohm coil ensures that relay coil will never burn, or even get warm for that matter.

And dont forget to replace the coil stops, ill mating plunger/coil stops contribute to flipper buzz.

One place to find the implementation of this was...Gottlieb!!

Some of the last wedgeheads had DC flippers, pops and kickers. Here is a snippet from Hit the Deck. Note that there is one bridge that feeds all the coils. You could probably just feed the flippers if you like.

That said, the first thing you should probably do is rebuild the flipper and see if you are OK with it then. The flippers will get very strong. Stronger than yellow dot. So you could end up with broken plastic and all that.

Note from the schematic that the coil is just a standard A-5194 with a 1N4004 diode across the lugs.

I had a game once that had two bridges installed. One for each flipper. I took them off, as once it was properly rebuilt, it was way too much with the DC mod.DC_Hit_the_Deck.JPG

True, except the flippers are A-17875s and the reset are the A-5194s.

Good catch. I looked up the specification differences between the A-17875 and the A-5141 and they are as follows (from John's Jukes)

A-5141 GOTTLIEB REG l.9 6.1 ohms
A-17875 GOTTLIEB REG 2.8 40 ohms

So they are different. Probably to tune them down a bit and not have all the broken plastic etc. The 17875 coils are just system 1s.

For an EM game replacement coil, you *must* remove any diode which may come pre-installed.

For DC operation in an EM game, I still give that advice because it does nothing except create a possibility to connect the coil leads backwards and burn out the rectifier and/or smoke the diode.

I'm experimenting with Vishay rectifiers on some pops... they're really cool. But a bit too powerful! I'm winding about 70 feet of coil wire around each to increase the resistance and get the feel dialed in just right.

Wouldn't it help to protect the rectifier by placing an IN4007 across the coil leads? It's a closed DC circuit once the rectifier is added... so what could it hurt?

Also, bigger current means bigger sparks. I'm wondering if the pop relays will need bigger switch contacts to handle the extra juice...

i would use a diode either a in4007 or in4004 i also would fuse it.
the later gottliebs that had the pops/flippers rectified had the high current tungsten contacts

No. The only reason Solid State pins have Diodes is to protect the electronic from being damaged when the coil is deenergized.

As far as the flippers, a Capacitor across the leads of the E.O.S. switch will help reduce sparking when the switch opens. Gottlieb and Williams did this Here's an example:
http://www.marcospecialties.com/pinball-parts/26438

Hello,

I finally got a Gottlieb chime and I would like to use it with a 12V DC power supply.

The 3 coils are:

- Goettlieb ref. A-5195
- voltage: 28 volts AC (I think)
- coil resistance:12.3 ohms
- wire gauge: 26
- wire turns:1305
- wrapper color: white

On several places I can read that it's possible to convert an AC coil to use it with a DC power supply.

The first thing is to add a 1n4007 diode but I can find any information about the safety/danger of powering an AC 28V coil with a DC 12V (+diode).

Should I only use the same 28V voltage in DC ? I'm afraid the plungers will hit the bars too hard with 24V DC, damaging the nylon tip and making a too loud sound , also I don't want to burn the coil...

Some expert advice ? Thanks )

I did this successfully over this past weekend with an old 1974 Gottlieb Magnotron with anemic flippers and bumpers. I installed 1 bridge rectifier, with fuse and capacitor for each item I converted. This game had 3 bumpers so 3 sets of BR, fuse & Cap.. Did the same with the flippers. 1 set for each flipper.

The fire power of the bumpers were incredible! Same with the flippers. Much stronger plus no more annoying coil buzz. Here is a link to a short video showing the bumpers after the conversion.

Joe

The gottlieb system 1s used the same chime units in cleopatra, Joker Poker and Sinbad before switching to electronic sounds. They run at 24V DC, but my cleo and jp manuals show them using a A-17876 coil instead of the A-5195, which if I understand correctly the A-17876 is not nearly as strong a pull as the A-5195 (24ohm vs 12ohm). I don't know how well a A-5195 would work with 12V, my guess would be not enough oomph, but it would be easy enough to try, or you could pick up some A-17876 coils and run at the 24V of the system 1 machines.

Oh, and from what I've read there is really no difference between an AC coil and a DC coil besides the added diode. I have several of the A-5195 coils in my system 1 machines.

Ok thanks guys, I'll give it try with a 12V DC power supply and if it doesn't trigger the coils I'll try the suggested options. And just in case I will monitor the coils heat with a little temperature probe, actually it's my biggest concern. I'll let you know soon.

Hello manples,

does your AC to DC coil conversion worked out?
because I like to do the same.
I have a AC coil chime unit in my hands and I don't want to destroy it.

cheers
Sascha

A bridge rectifier IS an electronic (ie, solid-state) device, essentially a simplified transistor with no base layer. Therefore, a high-voltage back-EMF spike from a coil when it shuts off could break down the P-N junction in one of the diodes in the bridge. I'm pretty sure that's why you sometimes find one shorted leg in the under-PF rectifiers of early 70s Williams games. Those games ran their bumper and kicker coils on DC, but didn't have back-EMF diodes on those coils.

- TimMe

I picked up some rectifiers from China on eBay for 20¢ apiece in order to use them on the five pop bumpers on my Williams Doozie. Doozie has the same 5 pop bumper arrangement that was later used on a number of games, including Funfest/Swinger.

The latter games have DC pops, and they're a lot more peppy than Doozie, so I thought I could replicate that hot pop bumper action by adding rectifiers and converting the pops to DC.

WHOA! The results were ....just a bit more than I had expected. Actually, these pop bumpers are so powerful that I'm concerned that things are going to break, and that includes the playfield glass. I ended up with pop bumpers with insane, over the top, crazy with a capital C performance.

I played two games and removed the rectifiers. Yeah, they work, but they made the pop bumpers WAAAAAAAY too powerful to be useful.

So how do we remove the flipper buzz and increase the flipper strength? I'm still confused as to the best/safest approach.

Thanks for the video, Joe. Really takes me back to the Gottlieb Target Pool I converted many years ago.

Are they Gottliebs? Try swapping orange dot or yellow dot flipper coils and install a tension washer.

These things can happen when you vary from the original design. If you modify one part then there may be another that should be taken into consideration too, say maybe the coils?

I just shop the games out and leave them factory stock and they play the way they are supposed to play. If it doesn't suit me like that, I'll just move on to another one. No use trying to polish a turd. Or supercharge one for that matter.

Williams disagreed; they kept the same pop bumper arrangement used on Doozie for later games but added rectifier circuitry to make the pop bumpers more responsive. Clearly, they weren't happy with the status quo.

What they also did, it would appear, was use somewhat less powerful coils in the games with DC pop bumpers. I could replicate that by keeping the rectifiers and swapping out coils for the ones used in later games, but I've decided to go back to AC.

I don't mind occasional small mods, but I'm not trying to build a Frankenpin here.

Just curious, is your game high tapped already?

I did the DC mod to my Gottlieb flippers and it worked very well. (no BUZZ)

Some details here:

https://pinside.com/pinball/forum/topic/wild-life-or-jungle-resto-and-mods#post-3756473

Bud

Not really. At the time Doozie came out the technology was there, but they felt releasing the game the way it was was fine.

What happened later was just part of pinball evolution as games got faster and scoring got higher. Note Doozie only has four score reels and windows where the later games had five or six.

But this was the main point I was trying to make with that post.

Since pop bumpers are normally only on for a brief moment, coil changes may not be necessary unless as was described (the end result is just too damn strong). Always insure game is not on high tap if adding the DC bridge rectifiers. But if too strong, you can do what was suggested earlier in the thread to convert from the EM AC coils to the later DC coils (like for gottlieb going from A-4893 coils to A-5194)

As to Flipper, unless you take the above linked-to method of Budwin and install high wattage power resistors in line with the end of stroke switches, you MUST go from the old AC flipper coils to newer DC coils due to the amount of heat generated by the AC hold winding when run on DC current. I am pretty sure you can find an equivalent coil body in DC to match the older AC flipper frames in every manufacturer and voltage.

Keep in mind, that when going DC on flippers, they too may prove to be too strong (and possibly destructive). It is usually necessary to open the EOS gaps up very wide when the flippers are in the fully up position (Still must be closed at rest), to reduce power. It will probably be a good idea to go from Wood Screw post screws to Machine screws with T-Nuts for any rubber ring post in close direct sight of the flippers or you will have posts ripping out the wood screws over time.

From memory, Gottlieb at the end of the EM era used DC flippers on a few of their games. So they already engineered what needs to be done if that is the route somebody wants to take. Results however may.... never mind.

Basically, you use the same coils as are used in Early Solid State games and you should be okay (other than the out of pocket money at around $10 per coil!). This is where NicVolta and others that use the route of pulling off X number of windings instead of going DC is much more cost effective (just not as easily reversible).

Yeah, that fully rectified playfield Joker Poker I had played fast as heck, and I remember the one I played on route was the same way.

I'm just not so sure I'd want that on the older games that played fine without them. I like to experience the evolution of pinball even as I play today.

But, to each his own I guess. Most modifications can be undone if future owners want them back to the way the factories saw fit to make them.

just a follow up on the use of dc flippers and coils. I have created an arduino solution based on an orginal gottlieb flying carpet. I used the standard gottlieb coils for this em machine with protection diodes across the coils. I powered the pop bumpers from 12 volts dc and the flippers from 15 volts dc. works great no hot coils. did pwm the hold coil on the flippers since resistance is very low around 6 ohms. So yes you can power via dc and you can adjust the strength via the adjustment on the psu. Search bjmclrn pinball snd you can see my flying carpet

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