(Topic ID: 62116)

LED "Flickering" 1.5K Resistor Trick

By snyper2099

8 years ago


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  • 38 posts
  • 26 Pinsiders participating
  • Latest reply 10 months ago by gdonovan
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    #1 8 years ago

    So there are a ton of LED problem type threads but I tried this yesterday on the advice of another pinsider and was really shocked as to how well it works.

    For me, this is mostly an issue on early Solid State Bally/Stern games but it does also apply to other era machines...

    I often have a game where I only want to put a few LEDs in it in order to brighten certain things up. Like replacing an incandescent GI bulb or a purple/green feature lamp simply because it is not clearly lit.

    If you use LEDs that have an unwanted flickering effect, simply solder a 1.5K 1/4 watt resistor across the two bulb lugs and all ghosting/flickering is eliminated.

    This would obviously not work well for an entire machine/playfield but is great if you are only adding a few LEDs here and there that have unwanted flickering.

    Total cost is like .05 cents for a resistor. If you have already purchased LEDs that ghost, this could help out some on certain projects.

    I do realize there are aftermarket PCBs and anti-flickering LED bulbs now but if you already have purchased a bunch of LEDs that have this issue, it may help someone.

    #2 8 years ago

    Thanks for the heads up! I'll have to try that sometime.

    #3 8 years ago

    Did it on my Xenon. Led the whole thing. Marked the sockets that where flickering/ghosting. Put resistor across lugs of said sockets and perfecto. No need for 100 dollar altek lamp board.

    -Jim

    #4 8 years ago

    Is the consensus the correct resistor to use in this application is the 1.5Kohm instead of the previously recommended 470ohm?

    #5 8 years ago

    From KenH (pinside member)

    "You're well within safe limits using 490 ohm resistors.

    V=IR, or I=V/R,

    for the 490 ohm, the current would be 6/490, about 12 mA, plus say about 40mA for the LED itself, lets round it to about 50mA total, per lamp.

    The SCRs on Bally's are rated to drive a standard #44 bulb, that draws 125mA."

    #6 8 years ago

    Does this also reduce the peak brightness for the LED? If so, that's something I really need to try. I have a few pins where I only want to fix the insert color (make them truly blue, instead of purple).

    #7 8 years ago

    You're confusing ghosting with SCR latch drop induced flickering.

    On old Bally's/Classic Stern, the incandescent lamps drew enough amperage to keep the controlling transistor (SCR) latched on (It's 250ma for #44/#555, 150ma for #47). Once you put in a LED, they consume significantly less amperage, in the 10ma to 40ma range depending. Therefore the SCR drops the sink causing the LED to go out, only to have the CPU tell it to turn back on on the next refresh cycle causing the LED to turn back on. Depending on when the drop occurs and refresh, it make it seem like a random flicker.

    Ghosting, on the other hand is when a lamp matrix is used (Bally/Classic stern do NOT use a matrix--they have a separate wire going to every controlled lamp where matrixes share the same wires across up to 8 lamps) Ghosting appears as a dimly lit LED due to the pulse frequency of the voltage on the matrix.

    This fix to keep the SCR's latched has been known for a long time. There is another thread here the discusses the various resistor values tried and alternate ways to fix this problem:

    http://pinside.com/pinball/forum/topic/led-lights-in-bally-1978-ss-game-new-board-required

    #8 8 years ago

    I will correct the title to flickering. Thanks for the clarification.

    I have never seen ghosting then... Is there a confirmed game/LED type where ghosting always occurs?

    #9 8 years ago

    LOL im the one that brought the 1k-1.5k shunt trick here to pinside and showed all my FB friends, this trick does also work for ghosting on new b/w machines as well if you use a 470ohm resistor.
    Funny everyone pretty much called me a liar at first now people are actualy giving it as advice lol.
    Also need to note the 1.5k only works on SS bally stern machines, other machines need different values.
    Premium leds are also no longer required when using this technique.

    #10 8 years ago
    Quoted from snyper2099:

    Is there a confirmed game/LED type where ghosting always occurs?

    Basically any game that uses a matrix -- E.g. Besides classic Bally/Stern, most everything else. Some newer ones can have software based fixes. Older ones simply require blocking capacitors (non ghosting) LEDs; or you deal with it.

    Both of my System11 games exhibit ghosting -- though it's minor enough that I can live with the low amount, and infrequent times it occurs and stick with 30c LEDs instead of $1.50 ones in different styles/brightnesses as well. Other games it is so bad that people must convert to non-ghosting LEDs, upgrade firmware or try other techniques.

    #11 8 years ago
    Quoted from snyper2099:

    I will correct the title to flickering. Thanks for the clarification.
    I have never seen ghosting then... Is there a confirmed game/LED type where ghosting always occurs?

    To my knowledge any lamp matrix with 'standard' led's will ghost to varying degrees.

    My understanding is the low resistance of the LED and the frequency of the matrix scan works together to cause flickering of associated row/column lamps (depending on which is the driver). With incandescents, the resistance meant there was a time requirement before a lamp saw enough power to glow. Same thing happens with flash lamps in older games like High Speed where warming resisters were used - the bulbs are always seeing current but not enough to glow due to high resistance in the circuit. If you drop in LED flashers, they latch on immediately because of the low resistance.

    If im wrong ill hopefully be corrected.

    #12 8 years ago
    Quoted from Pac-Fan:

    Basically any game that uses a matrix -- E.g. Besides classic Bally/Stern, most everything else. Some newer ones can have software based fixes. Older ones simply require blocking capacitors (non ghosting) LEDs; or you deal with it.
    Both of my System11 games exhibit ghosting -- though it's minor enough that I can live with the low amount, and infrequent times it occurs and stick with 30c LEDs instead of $1.50 ones in different styles/brightnesses as well. Other games it is so bad that people must convert to non-ghosting LEDs, upgrade firmware or try other techniques.

    +1 the terminology gets confused often.

    I used the resistor mod (to cure FLICKERING) for my Ballys and it worked well, with 470 ohm resistors.
    I found GHOSTING on my Williams High Speed very small, not even noticeable except for when I was looking at it. On a Williams Taxi it was way worse, so bad I converted it back to incandescent.

    #13 8 years ago
    Quoted from wayout440:

    +1 the terminology gets confused often.
    I used the resistor mod for my Ballys and it worked well, with 470 ohm resistors.
    I found ghosting on my Williams High Speed very small, not even noticeable except for when I was looking at it. On a Williams Taxi it was way worse, so bad I converted it back to incandescent.

    Yeah my HS barely shows it.

    My buddies WOF is blinding with ghosting.

    #14 8 years ago
    Quoted from Purpledrilmonkey:

    To my knowledge any lamp matrix with 'standard' led's will ghost to varying degrees.
    ...

    This is not 100% correct. In fact it is a timing issue in the matrix and mainly happens on WPC, WPC-S and some WPC95 machines.
    Willams has changed this in newer machines. There is a patch for several games, which solves the
    issue the same way Williams solved it. I have used the patch in my STTNG and ghosting is not noticable anymore.

    #15 8 years ago
    Quoted from Pac-Fan:

    Basically any game that uses a matrix -- E.g. Besides classic Bally/Stern, most everything else. Some newer ones can have software based fixes. Older ones simply require blocking capacitors (non ghosting) LEDs; or you deal with it.
    Both of my System11 games exhibit ghosting -- though it's minor enough that I can live with the low amount, and infrequent times it occurs and stick with 30c LEDs instead of $1.50 ones in different styles/brightnesses as well. Other games it is so bad that people must convert to non-ghosting LEDs, upgrade firmware or try other techniques.

    Actually most games do not ghost even with a matrix. The worst offenders are anything on stern whitestar.

    #16 8 years ago
    Quoted from markmon:

    Actually most games do not ghost even with a matrix. The worst offenders are anything on stern whitestar.

    hmmm...not familiar with the amount of ghosting on a Stern Whitestar. I know system 11s get it pretty bad though.

    #17 8 years ago
    Quoted from flugs:

    This is not 100% correct. In fact it is a timing issue in the matrix and mainly happens on WPC, WPC-S and some WPC95 machines.
    Willams has changed this in newer machines. There is a patch for several games, which solves the
    issue the same way Williams solved it. I have used the patch in my STTNG and ghosting is not noticable anymore.

    So there are matrix games that do not ghost at all? I realize it differs game to game (as i mentioned) but I've seen ghosting in everything from sys11 to stern SAM. Some are way worse than others and I certainly haven't played every game from every manufacturer but I have yet to hear of a matrix based lamp system that doesn't ghost at all from the factory.

    #18 8 years ago

    I did a complete LED job in My Bally "Star Trek" using the resistor trick. I used 1K resistors for my conversion and yes I did do ALL the controlled playfield sockets! Ordered 100 1K resistors off of ebay. Set me back an entire $1.49 including shipping! I also used the opportunity to fix the Bally lamp holders that we all know are pretty bad. They get loose after time and start to go intermittent. To fix them you need to solder the socket to the bracket and solder the wire to the "nub". Also to make the LEDs work without flickering you need to solder a 1K resistor across the terminals of the socket. So I decided to kill 2 birds with one stone. Look at how I soldered in the resistor to the lamp socket:

    // Error: Image 118977 not found //

    As you can see I soldered the socket to the bracket at the edge where they meet. I also used this as one point to solder one end of the resistor. The other end of the resistor I soldered directly to the socket "nib" AND also the tab where the wire is soldered to. This creates a solid conection between the "nib", wire, and the other end of the resistor. Lamps are all now very solid and the LEDs work perfectly with no flicker!

    I also used this same technique on my Game Plan Star Trip cocktail pin. It had the same flickering issue. It seems that any resistor between 470 - 1.5K should work just fine.

    Here is a video I put together showing the full LED conversion in my Bally Star Trek:

    3 weeks later
    #19 8 years ago

    I am the unlucky owner of a RBION which is a whitestar and therefore ghosts badly with LEDs. Tried a few LEDs in it including " non ghosting premium 2' " .....yeah right! . All types ghost. Will the resistor trick sort it for me? Most of the lamps are 555's in plastic sockets so will be awkward but probably doable.

    #20 8 years ago
    Quoted from Kevlar:

    Will the resistor trick sort it for me?

    Probably not. Ghosting is an entirely different problem than the blinking or flickering problem the early Bally pins have. Ghosting is caused by the lamp matrix bleeding a small amount of voltage into the bulb. It doesn't affect a regular incandescent but it will cause an LED to light up dimly or "ghost". The non ghosting LEDs have a capacitor built in that supposed to eliminate the problem. In some systems it works but in others it doesn't.

    You may want to contact Art at www.cometpinball.com as he has a new bulb coming in very soon that may work for your problem. It is a specially engineered bulb made especially for pinball use that should eliminate the ghosting problem. It has both capacitors and resistors built in that should cure almost any ghosting, strobing, or flickering problem. Great prices too!!

    Good luck!!

    #21 8 years ago
    Quoted from markmon:

    Actually most games do not ghost even with a matrix. The worst offenders are anything on stern whitestar.

    +1. My Sega pins are the worst offenders. I can pretty much live with the small amount of ghosting on most of my machines, but Starship Troopers and Batman Forever are the only pins I have where the ghosting drives me nuts....

    #22 8 years ago

    My Williams System 6 FP ghosts very slightly only in a few locations. Some locations never ghost, others ghost almost constantly. Not bright enough to be distracting to me. I may try the resistor trick if I am bored one day. More likely I will order some non-ghosting LEDs for these locations only.

    #23 8 years ago
    Quoted from Schwaggs:

    My Williams System 6 FP ghosts very slightly only in a few locations. Some locations never ghost, others ghost almost constantly. Not bright enough to be distracting to me. I may try the resistor trick if I am bored one day. More likely I will order some non-ghosting LEDs for these locations only.

    There are a few inserts and a most of the matrix controlled lights up above the pf on JP that flicker. I wasn't able to get it to stop with a resistor, and I tried several values. I'm using regular cheap Ablaze LEDs from pinball life. It's not bad enough in this game to invest in other bulbs at this time.

    #24 8 years ago

    What about gottlieb games??? System 80 or 3? Since there is no technical matrix on these, is there any help for the resistor trick on these?

    #25 8 years ago
    Quoted from Kevlar:

    I am the unlucky owner of a RBION which is a whitestar and therefore ghosts badly with LEDs. Tried a few LEDs in it including " non ghosting premium 2' " .....yeah right! . All types ghost. Will the resistor trick sort it for me? Most of the lamps are 555's in plastic sockets so will be awkward but probably doable.

    I put pinballbulbs LEDs in my RBION and they don't ghost. Used the non-ghosting of course. They still do the whitestar fast flicker thing though. LEDs are just too responsive it seems to avoid that, but they don't light when not supposed to.

    #26 8 years ago

    I have a STTNG and the shield inserts in front of the Enterprise are fine in attract mode when they are on full power, but during gameplay (I think they are dimmed to show shield strength) they look like strobe lights. Is there any trick to fix the flicker on those?

    #27 8 years ago
    Quoted from action76:

    I have a STTNG and the shield inserts in front of the Enterprise are fine in attract mode when they are on full power, but during gameplay (I think they are dimmed to show shield strength) they look like strobe lights. Is there any trick to fix the flicker on those?

    On williams games turn off setting A25

    #28 8 years ago

    On Stern Whitestar games, insert ghosting and flickering can be resolved using Herg's LED OCD board. GI, on the other hand .. I haven't tackled that problem myself on my Lord or Tron, but soooon.

    Sounds like I'll be ordering some resistors..

    #29 8 years ago
    Quoted from jrivelli:

    On williams games turn off setting A25

    Sweet, I'll try that when I get home. Are those lamps considered GI? I guess they are but I always considered them to be controlled lamps. Probably why I didn't think of changing that setting. Thanks.

    #30 8 years ago
    Quoted from action76:

    Sweet, I'll try that when I get home. Are those lamps considered GI? I guess they are but I always considered them to be controlled lamps. Probably why I didn't think of changing that setting. Thanks

    They are GI lamps. Not controlled on/off by the lamp matrix but just dimmed by the SCRs on the power driver board. Changing that setting just won't allow the GI strings to dim.

    1 year later
    #31 7 years ago

    Hi there,

    Had a problem on my Bally Strange Science where some of the LED's would barely light. When I put an incandescent bulb in parallel to the LED everything worked fine.

    Went out and bought some 470 ohm resistors and bent them round the wedge of the LED and put the back in. Problem solved!!! No soldering required.

    2014-11-23 15.31.35-987.jpg

    2014-11-23 14.49.12-284.jpg

    #32 7 years ago
    Quoted from Kevlar:

    I am the unlucky owner of a RBION which is a whitestar and therefore ghosts badly with LEDs. Tried a few LEDs in it including " non ghosting premium 2' " .....yeah right! . All types ghost. Will the resistor trick sort it for me? Most of the lamps are 555's in plastic sockets so will be awkward but probably doable.

    Actually RBION has zero ghosting with non ghosting leds. You just likeky have an actual lamp matrix problem.

    6 years later
    #33 10 months ago

    Will the 1/4 watt resistors work on a Williams System 6 machine? 1980 Blackout.

    #34 10 months ago

    You really can't use LEDs on Stern Whitestar games. i mean you can but they will look awful, not matter the type. it has to do with how the lamps were programmed. if you look at regular bulbs on these game, they use a really nice power up/power down effect. it's really cool and well done! but with LEDs that goes out the window and looks like flickering hell. i don't know anyway to fix that, so i keep regular bulbs there.

    You can use the OCD board, that is a good solution. but it costs money...

    #35 10 months ago
    Quoted from Flip-it-good:

    Will the 1/4 watt resistors work on a Williams System 6 machine? 1980 Blackout.

    No need. Just replace the bulbs with LEDs. This system of game have no ghosting or flickering issues. I just did a blackout with comet smd frosted warm white and it came out great.

    #36 10 months ago
    Quoted from cfh:

    i don't know anyway to fix that,

    Quoted from cfh:

    You can use the OCD board

    #37 10 months ago

    Fantastic, thank you!

    #38 10 months ago
    Quoted from chuckwurt:

    No need. Just replace the bulbs with LEDs. This system of game have no ghosting or flickering issues. I just did a blackout with comet smd frosted warm white and it came out great.

    I did mine a year ago, can confirm. Looks great!

    2cd95882b414993ceb482a979520033a9ee3ea8e (resized).jpg

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