(Topic ID: 49434)

LED lights in Bally 1978 SS game - new board required??????

By rufessor

6 years ago

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  • 78 posts
  • 28 Pinsiders participating
  • Latest reply 1 year ago by rufessor
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#4 6 years ago

The issue is not with ghosting or the inherent flicker in an LED. Rather, on Bally's, the controlling transistors (SCRs--silicon controlled rectifiers specificially) they used require a specific amount of current running in order to stay latched (on). If the current (amp) draw falls below a threshold, the scr turns off, then turns back on, causing a very noticeable and random flicker of the LED.

There are multiple fixes:
1) Use a big enough LED array within a single lamp that causes enough current to be pulled. You'll find that most cheap LED's draw 10 to 20 ma vs the 150 to 250 ma of a #47/#44 incandescent. If you find a LED lamp that has multiple sub-leds that increase amp draw they won't cause the SCR to unlatch. However the side effect will be extra cost and way too bright for the insert, so not doable for most.

2) Cause additional current to be pulled without creating light (or heat) to the level the SCR needs at a minimum. This is as simple as soldering a single, 470 ohm resistor across every single switched lamp socket underneath. A resistor costs 1 to 5 cents each in bulk depending on your source, and just need time to solder. This fix simply 'sinks' some of the power from the +5.9V lamp line to ground through the SCR at the socket making it appear more current than the LED uses is being drawn when the SCR is on. The nice thing is this doesn't prevent you from using an incandescent lamp as the resistance is higher than the lamp, so electricity will follow the least resistance--the lamp. The only bad thing about this is you have about 60 sockets to solder 2 wires to and makes it 'non original'.

3) Buy a new $100+ board that uses newer transistors to not require such high current draw.

I am working on an alternate solution costing much much less than a $100 board or soldering 120+ wires underneath the playfield. I have a prototype completed, tested and working, and am considering offering something up if there is enough interest. It would be completely plug-n-play and not require removal/replacement of any board or soldering or underplayfield access. The cost to fab the boards would be significant so would need to judge demand before I take the plunge LMK if anyone is interested, and I may consider this this summer.

BTW--This only affect switched lamps. GI / Backglass lamps are not affected because they either use mechanical relays in some cases or there are enough lamps on a single SCR to maintain enough current.

#9 6 years ago
Quoted from wayout440:

easily go back to incandescent bulbs.

You don't have to remove the resistor to go back to normal incandescent. The lamps work fine with it still in place as they have lower resistance than the resistor.

Quoted from wayout440:

^ this is for controlled lamps only

Yep, as I stated at the bottom of my message

Quoted from Pac-Fan:

BTW--This only affect switched lamps. GI / Backglass lamps are not affected because they either use mechanical relays in some cases or there are enough lamps on a single SCR to maintain enough current.


Quoted from Xenon75:

I would be quite interested. Probably 7+ boards depending on cost.

Wow.. Okay, 7 sets (each game would require 3x mini boards to interface with the connectors/harness) of boards would probably cover my first PCB fab run. I haven't priced things out, but a friend who does a lot of fab-ing for some battery charger projects thought there would be no problem in doing this for about $30 for a set of boards (PCB fab, installed components soldered in, testing). Is that within a reasonable range -- $30 per game?

#11 6 years ago

Also, want to add explicitly (I touched on it above) -- Ghosting is NOT an issue with the old Bally's. Since a separate wire from a separate transistor is sent to each lamp socket with a common wire across the other side, there is no 'matrix' of rows/columns to deal with, so turning on other lamps cannot cause another lamp to have a phantom/ghost light.

Therefore once you solve the current draw limit of the old SCRs (for switched/controlled ones), and then optionally attack the overall GI issues with their power supply design causing other flicker, you can apply any LED to the game without having to pay more for non-ghosting/etc...

#13 6 years ago

GI is not an issue. There is more than enough amp draw on a chain of 10 LEDs controlled by a single SCR on a PF GI or backbox GI circuit... that pulls 2.5A if #44 incandescent normally which equals or .20A if they are 20ma LED's. At most any flickering that ever is noticed there is caused by the overall design of the power supply that on some machines drops the voltage to the GI when solenoids are firing/etc..

When you start witching to programmed/controlled/switched ones where there is one LED per SCR is when you will see the random flickering; and badly so. Since .250 A of a #44 is a lot more than a .02 A of a single LED for the latch to sense.

#16 6 years ago

The installation will take under 1 minute by anyone who at least knows how to change a fuse No soldering, no cutting, 100% removable in under a minute as well. Compatible with both incandescent and LED (can mix them together, don't have to remove to still use incandescent).

I have a prototype (non PCB based for now) working, and am pricing out a small test sample size PCB fab so I could get a couple made and send out for someone to test after I verify on my Bally. (As it took about 4 hours to wire strip, cut, crimp, solder all the components for the prototype set :(so I'm not going to hand make these!)

If all goes well with a sample and beta test, then I could then do a large run and make them available. ETA is this summer. Right now I'm trying to figure out the best design (board layout) both in terms of quick assembly on my side, and quick and solid installation on a game, plus optimizing size for highest yield as PCB fab is pretty spendy.

Thanks for the interest! The more stating interest, the higher I will prioritize completing this over trying to get my Bally acquisition fully working

If you are interested, send me (or post here) a list of machines you would consider putting it in, and if possible, a picture of the back side of the backbox lamp boards on them (showing any aux driver board positions) so that I can verify a couple of assumptions about positions of those boards. Thanks!

#20 6 years ago
Quoted from rufessor:

Interested- need to see what in fact it is your making but price seems right and its needed. Maybe let us know whats up or show a pic.

It will be a set of 3 mini boards with circuitry that will interface between the connectors and the wire harness off the lamp board, along with another much smaller board to interface with the square Aux Driver board elsewhere to pick up an additional signal. (I'm making an assumption that every backbox has at least one AS-2518-68 Aux. Driver GI Flasher or an AS-2518-82 Aux Driver TRIAC Lamp flasher mounted behind the backbox sockets---if that is not the case, then I need to look for alternatives (or require a single solder connection by the user)). I need to spend time flipping through some manuals or pictures but not a lot show the back side of the backbox lamp board so I can see where they are positioned.

Once I get the actual boards fab'd, I will post a video of the installation and results (with and without them installed). Given current interest, I will try to get these fab'd in the next 6 weeks.

#24 6 years ago

I haven't had a chance to pull out the board from Future Spa to take a pic of it, but I will get around to it and send you a link!

I am not looking for pictures of a particular board. I'm looking for a picture of the back side of the hinged wood panel that holds all of the backbox lighting. I'm trying to determine where the little 2"x2" AUX DRIVERS (not Aux Lamp Drivers--a different thing) are located on various ones. Attached is a sample of the type of picture I'm looking for.

I have 7 Bally machines of this era, from Strikes and Spares through Centaur. Do all of them have this issue and will this board set address the issue in all of them? I was hoping to convert them all eventually to LEDs.

As long as they are late 70's / early 80's Bally (or Stern) Solid State systems using the AS-2518-23 / AS-2518-14 or STERN LDA-100 lamp driver boards utilizing SCR's of type MCR-106 and 2N5060 / 2N5064, then they will exhibit this problem.

Ultimately, I would take one of these for each applicable machine (up to 10).

Awesome! Looks like I have enough requests, even if only 50% follow through, to make this a go. Finalizing layout, and then need to pick the right fab and get some of the adaptor boards produced. Thanks for everyone's interest!


I think this is the specific list of games that use the lamp driver boards:

Ali, Big Game, Black Pyramid, Centaur, Centaur II, Cheetah, Cosmic Princess, Dolly Parton, Dracula, Eight Ball, Eight Ball Deluxe, Elektra, Embryon, Fathom, Fireball Classic, Fireball II, Flash Gordon, Flight 2000, Future Spa, Galaxy, Gold Ball, Harlem Globetrotters On Tour, Hot Hand, Iron Maiden, Kings of Steel, KISS, Lectronamo, Lost World, Magic, Mata Hari, Medusa, Memory Lane, Meteor, Mr. & Mrs. Pac-Man, Night Rider, Nine Ball, Nitro Ground Shaker, Nugent, Orbitor 1, Paragon, Pinball, Bally Playboy, Power Play, Quicksilver, Rolling Stones, Silverball Mania, Six Million Dollar Man, Space Invaders, Speakeasy, Spectrum, Spy Hunter, Star Gazer, Star Trek, Stars, Stingray, Strikes and Spares, Vector, Viking, Viper, X's & O's, Xenon

1 month later
#28 6 years ago
Quoted from Jags:

found a 470 ohm, a 1.8K, a 3.3K which all worked and stopped the flickering. Also tried a 9.1K and a 22K but they did not work. I guess they had too much resistance.

Thanks for the information. I wondered myself, at what level the SCR actually needed to stay latched. I hadn't gotten around to trying multiple sizes, since 470K was the semi-standard published by enthusiasts.

Quoted from Jags:

Once I get them I'll fire up the old soldering iron and get to work

If you're willing to wait a few months, my kit will hopefully be done and save you all that soldering under the playfield But yeah, that the cheapest (money) but most expensive (labor) fix for it.

Quoted from Jags:

don't offer a bulb with the resistor already built

Because that would be extra power draw across the socket and would negate some of the benefits of LEDing in many games -- slightly increasing heat; etc. -- not useful if the game doesn't have the problem to begin with. It would be an extra cost to assemble each bulb as well to address only a small subset of Bally/Stern games from the late 70's/early 80's (as compared to where most of their income comes from -- Mid 80's to now. Plus; as with the non-ghosting ones, there are a very limited sub-set of lamps that use them, limiting your choices.

Quoted from Jags:

What is it that they put into a non ghosting bulb anyway?

A capacitor is used to require a certain level of power to flow in to charge it up before it allows it to go onward to the bulb. Ghost voltages will slightly charge the capacitor but not allow the LED to light. If you've got a EE and CS background, here's a site that details the ghosting problem on later pins: http://emmytech.com/arcade/led_ghost_busting/index.html

Quoted from DallasPinball:

would be interested in buying atleast one set to try and if it works, I will probably buy enough to cover all of my early Bally/Stern pins. Thanks!


Short update: Between work, and acquiring another pin / things have slowed a bit on the project but I still am looking at summer to get the boards fabed and tested. The only small roadblock I've hit is that I have found that not all backboxes' light panels have a AUX DRIVER attached to them. That was a key point to providing a power signal without requiring the buyer to do any soldering. With the cost of wire (and neatness), I'm not looking forward to having someone run it all the way under the PF to a random location either. I'm going through some schems and pics to see what is 'common' across all the Bally games to see where I can make a single plug-though connector to gather the signal I need making it fully plug and play in all circumstances.

1 month later
#34 6 years ago
Quoted from rufessor:

I wonder if it would be possible to trace these wires back to the control board and somehow put a resistor in line there?
so this is a 1 minute mod at that point...

That's basically what my boards will do. However it is not a 1 minute mod. It took me 3 hours to bend, wrap, cut and solder about 70 resistors across every terminal to the destination on a inline adaptor on each of the board on my prototype -- About the same time it would take to do it at each socket. (Dealing with .100 spacing and tiny SIP connector adaptor legs does take time to ensure no solder bridges are formed/etc.. -- definitely not the wide open space of soldering directly on the socket)

The final circuit will be on a PCB with SIP style resistor arrays that will be able to be soldered a lot quicker to make the product, and will work inline with the connectors. The problem is finding the common point to send all of the other ends of the resistors to without requiring end-user-soldering. In some games there are additional connectors nearby to hook into, others, it appears, from my looking at pictures and schems, it will require soldering. Perhaps I will just require that; and 1 connection soldered vs. up to 140 would be seen as a gain yet It still has the benefit of no 'damage' to any lamp socket or lamp driver board by soldering--especially by those that aren't that good and is 'instantly' removable in case you want to move it to another machine or something or need to replace the lamp driver board and not lose all that mod work.

I still am working on the project and hope to get the boards fab'd soon with more details later. Please hold out a little longer

2 months later
#63 5 years ago
Quoted from KenH:

make a 'pass thru' type connector using some stripboard, resistor SIPs, and connectors/headers, like this

That is exactly my prototype. (I'll try to post pics this weekend).

Sadly, my project (the $30 plug-n-play-no solder at all-solution) has not moved much. I can't find PCB production low enough to reduce the cost to a reasonable amount (e.g. I was hoping for under $20 in fab+headers, pins, SIP resistors for 3 boards + wire + solder) meaning about a $30 sale price once you factor in my time to design, order, solder, ship. Unfortunately all quotes I'm getting are hugely above that, giving a $40 cost of goods alone for the 3 boards each machine would need; and no one is gonna pay $50 for a solution. Especially considering the prototype was done with about $6 in core parts (resistors, SIP headers + pins), but about 2 hours of bending wire, cutting, fine soldering, etc...

I'm still looking to see if I can find a more reasonable PCB fab'er for these things to get them done yet for a $30 sale price per machine.

Quoted from Hellfire:

seriously $30-$100 for a board? lol you can get a 100x restistors for like $1.50 shipped to your door lol.

I agree $30 seems like a lot. But how many people
a) can solder successfully (no damage)
b) can solder to oxidized metal and make it stick
c) want to spend a couple hours soldering to 60 some sockets
d) want to 'damage' their otherwise original hardware (yeah that's an issue for some)

and would rather have a plug-n-play solution that doesn't require more than disconnecting 4 cables and reconnecting with boards between in under 5 minutes. Nope, it's not for everyone, just like the $100 replacement lamp boards aren't for everyone; but given the requests in this thread seems like such a product is wanted.

Now if only I or the other person working on similar could find a way to cheaply fab the fiberglass+copper; it could come to reality.

#65 5 years ago

The small one won't work, not enough pins across (J1/J3 are 28 pins). Bigger ones could work (with apparently very little extra cost), but since the traces are all inline, then you run into problems for the common connection point of the SIP resistor arrays (they would have to float above the board and jumper wire soldered directly to it, thus being the first point of failure while installing. Perhaps offer a cheap, ugly, "no warranty if you break" option with those for $20 and the better designed ones for $30 -- If I can find a fab.

But definitely thanks for the suggestion; perhaps to get out "something" it's better than "nothing".

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