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(Topic ID: 89448)

LED backglass shut-off circuit for Stern machines (edited thread)


By Schwaggs

6 years ago



Topic Stats

  • 31 posts
  • 12 Pinsiders participating
  • Latest reply 6 years ago by herg
  • Topic is favorited by 8 Pinsiders

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    On-Delay Circuit.jpg

    #1 6 years ago

    The person I bought my Avenger from replaced the fluorescent tube lighting with LED lighting which provides bright, even lighting of the backglass but also lots of glare in addition to the stock DMD. I installed a DMD glare filter from PBL which works great for that part but the backglass glare was intense. I usually left the LEDs unplugged so I could see the PF.

    My final solution was to build a module that switches off the 12V power to the LED backglass mod when the right flipper button is pressed. About 30 seconds after the last flipper button press, the LED lighting gradually comes back on to full brightness over several seconds. The module optically isolates the 5V flipper button circuit from the 12V LED lighting circuit to protect your driver board circuity. I have been testing this module for about a month now and it has worked flawlessly during that time.

    The result is a perfectly clear view of the PF while playing a game. It looks like there is no glass installed on the machine if you are playing in a dark room (and your glass is clean ).

    Installation is a snap and is completely reversible. Simply plug the module into the Power Source Connector under the right flipper button, plug you LED backglass power cord into the module and clip an alligator clip onto the non-ground leg of the right flipper button (the side with only one wire solders onto it). The only drawback is that each time you first turn the machine on, the backlight will take around 30 seconds to come on (pretty minor if you ask me).

    Each module will be hand made and tested by me. They are not hard to make, but the molex connectors, soldering, shrink wrapping and testing does take some time. I figure I can make them for around $25 each plus whatever USPS costs.

    Is anyone interested in purchasing these? (remember this will only work on machines with LED backglass lighting mod, NOT with the stock Stern fluorescent light installed)

    If I were to publish the schematic, how many people would want to make their own?

    #3 6 years ago

    Either way I am interested.

    #4 6 years ago
    Quoted from Out-West:

    Either way I am interested.

    Same here.

    #5 6 years ago

    FYI: I've got something like this in the works.

    OK, I read your message more closely. It looks like you're well under way too. Maybe we could collaborate on this a bit. I'll PM you.

    #6 6 years ago

    Maybe one of you could make something like this for older games, like WPC or older 80s games.

    I think Herg's GI OCD board basically does this, so I wouldn't need it there, but I have 10 early 80s Bally and Williams games that I would buy this for. Since LEDing those backglasses, the glare is pretty brutal.

    #7 6 years ago

    The idea is to have it work for as many games as possible. I've PM'ed Schwaggs some of the details.

    #8 6 years ago

    Cool. I've actually considered pulling the backglass LEDs in games like Fathom and Centaur because of the glare. I would definitely be in for something like this.

    #9 6 years ago
    Quoted from Cheeks:

    I think Herg's GI OCD board basically does this

    Yeah, but only for WPC95 and WPC89. It allows dimmed (or all the way off) backbox while playing. It's probably overkill if that's all you're looking for, though.

    A while back, Mike mentioned his project for other machines, and I've been patiently awaiting it for my Sterns. Whatever you guys come up with, I'll be interested. Completed kits are great since my time is limited, but I'd build my own if I had to.

    #10 6 years ago

    Thanks for feedback so far guys. My solution is fairly simple and therefore limited on the number of machines it will work with. From dkpinball's PM, it sounds like his idea is much more sophisticated and may be able to solve more problems than my idea.

    My idea WILL NOT work on machines with CPU driven backglass lighting like WPC era games. It would be possible to modify the circuit to work with 80s era, non CPU controlled lighting but the flipper switch connection on those machines would need to be worked out as they are high voltage and the modern Stern machines use logic level voltage. Additionally, for WPC era machines that Herg's GI OCD solution supports, a better solution would be to talk to him about adding a blanking function to optionally turn off the backglass circuits while a game is underway.

    I created a 1 minute video so you can see the effects... pretty dramatic difference eliminating the backglass glare makes!

    [attachment=1628551,]

    1 month later
    #11 6 years ago

    Any updates on this for Stern machines?

    Also, anyone have suggestions on where to get an LED replacement kit for <$100? Nothing fancy, just a few strips of LEDs on a board with a power connector. At >$100, I'm enough of a cheapskate to make my own.

    #12 6 years ago

    Herg, this might be what you want:

    http://www.arcadeupkeep.com/#/bb-fbb-board/4554278423

    #13 6 years ago

    Thanks. At $80, I'm still on the fence whether to build or buy, but that looks like what I want. I'd be doing 3 machines, and I already have a roll of LEDs, so making them myself would cost me time, but not a lot of dough.

    Now, if they could be dimmed to one level while not playing, and to a different level while playing, I'd be set.

    #14 6 years ago

    I'm interested in this module mod.

    #15 6 years ago

    Hey guys, I will post up the schematic later this week. It's been working flawlessly on my machine for months now and am comfortable sharing it now.

    #16 6 years ago

    I'd be interested in a few

    2 weeks later
    #17 6 years ago

    I'm still interested in this, and I actually went as far as implementing my own controller in my Tron.

    I originally designed a controller PCB that allows synchronization of the Eli ramp lights to a ColorDMD, speaker lights, etc. You can see pictures here:
    http://pinside.com/pinball/forum/topic/colordmd-color-changing-tron-pinbits-eli-ramps-integration#post-1728912

    Once I had that working, I realized I could use one of the "extra" transistors to drive an LED backbox panel. Since there's a microcontroller on the interface board, I can set it to any brightness I want through PWM rather than just ON/OFF. Also, due to a lucky coincidence, I had a couple of extra pins running from Eli's mod to the inputs of my microcontroller AND since my Eli kit is one of the prototypes, I have the source code.

    I modified the Eli ramp code to use one of the extra outputs to indicate whether the game is being played or in attract. The MCU on my interface board then uses that to dim and brighten the backbox accordingly. It works great! Unfortunately, it will only work for my very specific situation. I still want this sort of control for my Metallica and LOTR, so if either of you guys finalize something, let us know.

    Quoted from Schwaggs:

    Additionally, for WPC era machines that Herg's GI OCD solution supports, a better solution would be to talk to him about adding a blanking function to optionally turn off the backglass circuits while a game is underway.

    No need to add it. It's already in the design.

    #18 6 years ago

    Sorry I'm so late in posting the schematic. I need to find time.

    Quoted from herg:

    No need to add it. It's already in the design.

    Herg, can I drive incandescent bulbs with the GI OCD board or do I have to run all LEDs? If so, you sir have made a couple sales!

    #19 6 years ago
    Quoted from Schwaggs:

    Herg, can I drive incandescent bulbs with the GI OCD board or do I have to run all LEDs?

    We're kinda going off-topic, but you're the OP, so...

    You can drive "some" incandescent bulbs with GI OCD as long as you pay attention to the current draw. Around 2A per string and 10A total is the limit. To get the draw down to these levels, you'll have to swap most of the incandescents out for LEDs.

    1 week later
    #20 6 years ago

    Alright DIY'er, I finally got around to writing up the schematic and scanning it in. Sorry it took so long...

    Basic operation is:

    The open flipper button does not provide a path to ground for the opto LED. While the opto LED is off, the opto coupled transistor does not conduct which acts like a very high resistor. This allows C1 to slowly charge through R2. As it charges, the Gate voltage of Q1 rises to the point of saturation in about 30 seconds, turning the LED backlight on.

    When the flipper button is pressed, the opto LED is lit up, the opto transistor conducts. The transistor in the opto acts like a short to ground, rapidly discharging C1 to near zero volts turning off Q1.

    Hope this helps!

    On-Delay Circuit.jpg
    #21 6 years ago

    Hm, cool. Maybe I'll use this as a project to learn how to lay out a basic PCB. Seems like it would be a fun project for a noob like me, and would be easy to make a little harness to connect to the mod plug or a splitter to power the +5, +12, Ground..

    I wonder if I can just swap out the flourescent tube for a LED-based tube and then control it that way with this. I don't really want to spend 150 bucks or the effort to make my own LED backboard....perfectly happy with even, non-blingy lighting on my translite.

    #22 6 years ago

    I ended up making my own backboards, and it wasn't really that much work. A LED tube would require that you controlled the AC, making it much more difficult.

    Going back to one of schwagg's older posts, I saw the hint about using the flipper button, and just finished my own version of this a couple of nights ago. Rather than an RC circuit driving the FET, I have a microcontroller to do the timing and PWM the FET. The only real difference is that I can control the brightness this way.

    #23 6 years ago
    Quoted from herg:

    I ended up making my own backboards, and it wasn't really that much work. A LED tube would require that you controlled the AC, making it much more difficult.

    I have some local friends that converted their flourescent to a LED tube in the same fixture..it's probably not that big a deal....but if this is only useful for lightboards, no use in me wasting my time on something I can't use. I'll just put some parchment paper over the tube like I'd done with LOTR.

    #24 6 years ago
    Quoted from Frax:

    I'll just put some parchment paper over the tube like I'd done with LOTR.

    That works for reducing glare, but the main goal here is to have the backglass/translite look good while in attract, but not cause glare while playing. That requires something actively controlled.

    #25 6 years ago
    Quoted from herg:

    That works for reducing glare, but the main goal here is to have the backglass/translite look good while in attract, but not cause glare while playing. That requires something actively controlled.

    Depends on your personal definiton of "good", I guess. For me...it's "good enough". Definitely not worth spending 50-150 on a led backboard, 150$+ on EagleCAD, and god knows what on components, the PCB blanks, and harness to hook it up. My cheapskate solution definitely will not work for things like the animated LED panel for Tron that strobes the Portal beam...lol..

    #26 6 years ago
    Quoted from Frax:

    For me...it's "good enough".

    Then you're in the wrong thread. IMO, it needs to be lit fairly brightly to look good in attract, and if it's lit very brightly at all during game, it will cause glare.

    I'd estimate I spent about $20 each building my LED backboards. A roll of LED strip cost ~$15 and is enough for 2 with some left over. Add in the foam board, hardware, connectors, wire, etc., and you're around $20.

    The ready-made arcadeupkeep backboard that jayhawkui posted is $80, so your range is $20 - $80 for a plain lit panel. KiCAD is free. Components for mine cost less than $10, blank PCBs from OSHPark were <$7 each.

    #27 6 years ago

    THANK YOU FOR POSTING!
    Brad

    Quoted from Schwaggs:

    Alright DIY'er, I finally got around to writing up the schematic and scanning it in. Sorry it took so long...
    Basic operation is:
    The open flipper button does not provide a path to ground for the opto LED. While the opto LED is off, the opto coupled transistor does not conduct which acts like a very high resistor. This allows C1 to slowly charge through R2. As it charges, the Gate voltage of Q1 rises to the point of saturation in about 30 seconds, turning the LED backlight on.
    When the flipper button is pressed, the opto LED is lit up, the opto transistor conducts. The transistor in the opto acts like a short to ground, rapidly discharging C1 to near zero volts turning off Q1.
    Hope this helps!

    On-Delay Circuit.jpg 108 KB

    1 week later
    #28 6 years ago

    This circuit is SOOO simple, you do not need a circuit board. I was able to solder the components to each other with shrink wrap tubing on the joints, zip ties on the leads and a large piece of shrink wrap around the whole thing. The ground wire is a pass through so you zip tie the other leads to it to prevent pulling leads out of the circuit. I would advise you to use the 2N35 as the leads on it are a bit more beefy than the leads on the 2N25 and a radial capacitor and you should be able to solder the whole thing together without a board.

    Total parts cost is around $5 and that includes the connectors.

    #29 6 years ago
    Quoted from pinballnut:

    THANK YOU FOR POSTING!
    Brad

    You are welcome, have fun with it!

    #30 6 years ago
    Quoted from herg:

    Then you're in the wrong thread. IMO, it needs to be lit fairly brightly to look good in attract, and if it's lit very brightly at all during game, it will cause glare.
    I'd estimate I spent about $20 each building my LED backboards. A roll of LED strip cost ~$15 and is enough for 2 with some left over. Add in the foam board, hardware, connectors, wire, etc., and you're around $20.
    The ready-made arcadeupkeep backboard that jayhawkui posted is $80, so your range is $20 - $80 for a plain lit panel. KiCAD is free. Components for mine cost less than $10, blank PCBs from OSHPark were <$7 each.

    Can you make a how to thread on this? What size foam board? How do you change from the fluorescent to the board? How do you secure the board? Where do you get the power from?

    #31 6 years ago

    I don't really have the time to take all the pictures and write a thorough set of instructions that would be worthy of a new thread. It's pretty simple, though.

    Board size is about 24" x 15". Exact dimensions don't matter as long as it fits. I actually used the corrugated plastic sheet that you can get at Home Depot.

    Just take the fluorsecent bulb out and unscrew the electrical contacts. Using the same screw holes, a couple pieces of threaded rod, nuts, washers, and a couple of wing nuts hold the board.

    Power comes from the same 12V source as pretty much every Stern mod in existence. A convenient connector is inside the coin door, right side, but you will have to run wire up into the backbox if you use that connector.

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